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1

Phosphorus–nitrogen compounds: part 16. Synthesis, stereogenism, anisochronism and the relationship between 31 P NMR spectral and crystallographic data of monotopic spiro crypta phosphazene derivatives  

Microsoft Academic Search

The condensation reactions of N2O3-donor type coronands (1–3) with hexachlorocyclotriphosphazatriene, N3P3Cl6, resulted in the formation of spiro-crypta phosphazene derivatives (4–6). These compounds with excess morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) afford fully substituted morpholino (7 and 10) and 1,4-dioxa-8-azaspiro[4,5]deca (8)-substituted phosphazene derivatives, respectively. Whilst, in the same conditions, the reactions of 4, 5 and 6 with pyrrolidine, morpholine and DASD also produce

Zeynel K?l?ç; Aytu? Okumu?; ?emsay Demiriz; Selen Bilge; Asl? Öztürk; Nagihan Çaylak; Tuncer Hökelek

2009-01-01

2

Phosphorus-nitrogen compounds. Part 13. Syntheses, crystal structures, spectroscopic, stereogenic, and anisochronic properties of novel spiro-ansa-spiro-, spiro-bino-spiro-, and spiro-crypta phosphazene derivatives.  

PubMed

The condensation reactions of N2Ox (x = 2, 3) donor-type aminopodand (4) and dibenzo-diaza-crown ethers (5, 6, and 9) with hexachlorocyclotriphosphazatriene, N3P3Cl6, produce two kinds of partially substituted novel phosphazene derivatives, namely, spiro-bino-spiro- (19) and spiro-crypta (21, 22, and 25) phosphazenes. The partially substituted spiro-ansa-spiro-phosphazene (11) reacted with pyrrolidine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) give the corresponding new fully substituted phosphazenes (14 and 16). Unexpectedly, the reactions of 23 and 24 with pyrrolidine result in only geminal crypta phosphazenes (26 and 27). The solid-state structures of 16 and 22 have been determined by X-ray diffraction techniques. The relative inner hole-size of the macrocycle in the radii of 22 is 1.27 A. The relationship between the exocyclic NPN (alpha') and endocyclic (alpha) bond angles for spiro-crypta phosphazenes and exocyclic OPN (alpha') bond angles for spiro-ansa-spiro- and spiro-bino-spiro-phosphazenes with 31P NMR chemical shifts of NPN and OPN phosphorus atoms, respectively, have been investigated. The structures of 10, 14, 16, 19, 21, 22, and 25-27 have also been examined by FTIR, 1H, 13C, and 31P NMR, HETCOR, MS, and elemental analyses. The 31P NMR spectra of 10, 21, 22, and 25 indicate that the compounds have anisochrony. In compounds 16 and 22, the spirocyclic nitrogen atoms have pyramidal geometries resulting in stereogenic properties. PMID:17029388

Bilge, Selen; Demiriz, Semsay; Okumus, Aytug; Kiliç, Zeynel; Tercan, Baris; Hökelek, Tuncer; Büyükgüngör, Orhan

2006-10-16

3

Synthesis of Platinum Derivatives of Polymeric and Cyclic Phosphazenes.  

National Technical Information Service (NTIS)

Polymeric and oligomeric, water-soluble anticancer derivatives have been synthesized by the reaction of (NP(NHCH3)2)n or (NP(NHCH3)2)4 with K2PtCl4. Two types of compounds were isolated. The first was formed in organic media in the presence of 18-crown-6 ...

H. R. Allcock R. W. Allen J. P. O'Brien

1976-01-01

4

The investigation of structural and thermosensitive properties of new phosphazene derivatives bearing glycol and amino acid.  

PubMed

In this study, hexachlorocyclotriphosphazene, N(3)P(3)Cl(6) (cylotriphosphazene), was reacted with hydrophilic and hydrophobic groups to synthesize amphiphilic phosphazene derivatives (4-12). Cylotriphosphazene was reacted triethylene glycol monomethyl ether (TEGME), dipropylene glycol monomethyl ether (DPGME), diethylene glycol monobutyl ether (DEGBE), (1 : 3 mole proportion) in the presence of sodium hydride and using tetrahydrofuran (THF) as solvent at -60 °C. Three isomers (nongeminal cis-2,4,6 (1a-3a); nongeminal trans-2,4,6 (1b-3b); geminal 2,2,4 (1c-3c)) were isolated from the reaction of hexachlorocyclotriphosphazatriene (trimer) (1) with TEGME, DPGME and DEGBE. The substitution reactions of cis-tris isomers (1a-3a) with 4-amino butyric acid, 5-amino valeric acid and 6-amino hexanoic acid were separately done to provide amphiphilic phosphazenes (4-12). All compounds were characterized by using elemental analysis, (31)P NMR and mass spectroscopy. Thermosensitive properties of compounds were studied. The compounds (4-12) were soluble in both water and organic media that shows they are amphiphilic molecules. Concentration-dependent LCST (Lower Critical Solution Temperature) behaviours of new compounds (4-12) were measured in water. Compounds 7, 9, 11 and 12 exhibited a reversible and thermosensitive phase transition in aqueous medium, from soluble to insoluble states. PMID:20938539

Uslu, Aylin; Güvenalt?n, Sener

2010-11-28

5

Phosphazenes (2010)  

SciTech Connect

A review of the literature published in 2009 shows an increase in the number of publications addressing phosphazene chemistry over 2008, which suggests a continued strong interest in these intriguing materials. Prominently is the emphasis in the bioactive and biocompatible nature of these materials; although many other applications also exist. Phosphazenes are formed from a phosphorus and nitrogen backbone with pendant group attachments at phosphorus. Typically, they are drawn with alternating single and double bonds between the alternating phosphorus and nitrogen atoms. However, unlike the familiar poly(acetylenes) or poly(thiophenes), the phosphazene backbone is not electrically conductive as there are orbital nodes at phosphorus. Thus, electron delocalization occurs between phosphorus atoms, but not through them. The result of this bonding is a highly flexible backbone that can be controlled through adoit pendant group attachment revealing numerous materials and structures. In this review, novel aspects of the chemistry, structure, and applications of phosphazenes will be discussed.

Frederick F. Stewart

2010-12-01

6

Phosphazene diamines  

NASA Technical Reports Server (NTRS)

The synthesis of a specific phosphazene diamine was optimized, other phosphorus-containing diamines were prepared, and their effect upon certain characteristics of epoxy resins, prepared via reaction with MY 720, in particular, char yield at elevated temperatures was evaluated. The synthesis of the phosphazene diamine resulting from the interaction of methylenedianline with 4,4'-bis(diphenylphosphino)biphenyl was simplified into a one step process giving 77 percent yield of the pure product. Using this procedure, a related diamine containing bis(diphenylphosphino)methane was obtained in a 70 percent yield. Preparation of another class of phosphorus containing amines based upon p-aminophenyldiphenyl-phosphine was unsuccessful; the inability to produce p-aminophenylithlum was responsible for this failure. Seven epoxy resins employing Araldite MY 720, diaminodiphenylsulfone, and two of the phosphorus containing diamines were prepared, characterized, and their char yield capacity at elevated temperatures assessed. Based on these investigations, the resins containing phosphorus appear to exhibit significantly better char formation characteristics than materials hardened using conventional amines, without impairing the other properties measured.

Paciorek, K. L.; Harris, D. H.; Ito, T. I.; Kratzer, R. H.

1980-01-01

7

Friction-reducing and antiwear behavior of metal halide-stabilized linear phosphazene derivatives as lubricants for a steel-on-steel contact  

Microsoft Academic Search

A series of novel metal halide-stabilized linear phosphazene derivatives were synthesized. The friction-reducing and antiwear\\u000a abilities of the resulting products as the lubricants for a steel-on-steel contact were comparatively investigated on an Optimol\\u000a SRV oscillating friction and wear tester. The morphology of the worn steel surface was observed on a scanning electron microscope,\\u000a while the chemical states of some typical

Jiamei Zhu; Weimin Liu; Yongmin Liang

2005-01-01

8

Novel fire-resistant polyphosphazenes and phosphazene-containing polymers  

NASA Astrophysics Data System (ADS)

A functionalized polyphosphazene, poly[bis(carboxylatophenoxy)phosphazene], was blended with a structural polyurethane via reactive mixing of the polymer with diisocyanate and diol prepolymers. The thermal stabilities of the resultant foams were analyzed by thermogravimetric analysis (TGA). Both qualitative and quantitative flame tests indicated an increase in flame resistance at loadings of 20 wt% and above. Methods for the incorporation of phosphate and phosphonate units into the side groups of phosphazenes are described and evaluated. Halogenated organophosphates were used as the phosphorylating agents and were allowed to react with hydroxyl- or lithio-functionalized phosphazenes. Well defined phosphorylated cyclic trimers were synthesized from the hydroxyl-functionalized precursors, and these were examined as flame retardant additives to polystyrene. The thermal stabilities of the high polymers made by this route were analyzed by TGA. Ring-opening metathesis polymerization (ROMP) of phosphazene-functionalized norbornenes was demonstrated with the use of the Grubbs catalyst. This allowed the incorporation of alkoxy-, fluoroalkoxy-, and aryloxy-derived cyclic phosphazenes as side groups linked to the organic polymer backbone. The polymers were obtained in moderate yields with the properties being dependent on the side groups present and on the molecular weight. In addition, cyclooctenes and norbornenes with cyclic phosphazene side units bearing trifluoroethoxy or phenoxy groups were polymerized via ROMP using a ruthenium based initiator. The same monomers were also copolymerized with 90--99 mole percent of cyclooctene, norbornene, dicyclopentadiene, or exo,exo-5,6-bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]hept-2-ene. The presence of as little as 2 mol% of the cyclic phosphazene in the copolymers dramatically reduced the combustibility. Poly(diphenyl-p-styrylphosphine) and copolymers of diphenyl- p-styrylphosphine with either styrene or methyl methacrylate were functionalized via the Staudinger reaction with phosphazene cyclic trimers bearing an azide side group. The phosphazene rings bore trifluoroethoxy or phenoxy groups as the cosubstituents. All the polymers were characterized by multi-nuclear NMR, GPC, and DSC. The mechanisms of flame retardance were studied with TGA and OI methods. The chemical structures of the polymer backbone and of the phosphazene side groups affected the thermal stability and fire resistance of the final materials.

Taylor, Jonathan Paul

9

Hybrid phosphazene anodes for energy storage applications  

NASA Astrophysics Data System (ADS)

The use of hybrid cyclic phosphazene polymer/graphite anodes, where the phosphazene serves as distributed loci for Li deposition, has been investigated. Capacity within the hybrid system was found to occur reversibly in distinct regions. At the most positive voltages, above 0.06 V vs Li/Li+, the capacity was associated mostly with Li+ intercalation into graphite. In the most negative region, deposition of Li within the polymer was the predominate mechanism. A transitional region is inferred by the data whereby bulk aggregation or clustering of Li atoms occurs in proximity to the phosphazene sites that then serve as a template for more widespread population of Li within the anode at higher voltages, akin to a nucleation process. In full cells with a mixed oxide cathode, controlling the extent of Li deposition by limiting the charging voltage to 4.45 V enabled repeated cycling with no loss in capacity. Capacities as high as 183 mAh g-1 have been achieved for systems containing as little as 10% graphite while retaining coulombic efficiencies of 98% over 50 cycles. This level of cycling equates to the deposition of 7.4 Li per cyclic phosphazene.

Dufek, Eric J.; Stone, Mark L.; Jamison, David K.; Stewart, Frederick F.; Gering, Kevin L.; Petkovic, Lucia M.; Wilson, Aaron D.; Harrup, Mason K.; Rollins, Harry W.

2014-12-01

10

Thermolysis of Poly(bis(trifluoroethoxy)phosphazene).  

National Technical Information Service (NTIS)

Poly(bis(trifluoroethoxy)phosphazene), (NP(OCH2CF3)2)n, depolymerizes at temperatures above 150 to yield the cyclic trimer, tetramer, pentamer, higher oligomers, and medium molecular weight polymers. The reactions were studied by the use of gel permeation...

H. R. Allcock W. J. Cook

1973-01-01

11

Macromolecular Characterization of Poly(bis(M-Chlorophenoxy)-Phosphazene).  

National Technical Information Service (NTIS)

The macromolecular structures and structure-property relationships of five poly(bis(m-chlorophenoxy)phosphazene) samples are critically analyzed. The polymers are found to have high molecular weights and broad, bimodal molecular weight distributions. Diff...

G. L. Hagnauer B. R. LaLiberte R. E. Singler S. J. Kalian E. R. Plumer

1976-01-01

12

Additive Mechanism Investigation of Perfluoropolyether Lubricants with a Phosphazene Additive  

Microsoft Academic Search

The tribological characteristics of magnetic thin film media coated with perfluoropolyether (PFPE) lubricants (ZDOL and AM300J) and a phosphazene additive (X-IP) were investigated in this study. The drag test results show that under ambient and hot\\/wet conditions the media coated with AM300J lubricant have higher retention on the test track than those coated with ZDOL 2000 PFPE lubricant. The phosphazene

Chi L. Jiaa; Youmin Liu; Chao Gao

2000-01-01

13

Ring-Opening Polymerization of Siloxanes Using Phosphazene Base Catalysts  

Microsoft Academic Search

Phosphazene bases such as {(NMe2)3P=N–)3P=NBut} have been reported in the literature to be strongly basic materials with basicities up to 1×1018 times stronger than that of diazabicycloundecene (DBU) a strong hindered amine base used in organic reactions. A study of these phosphazene bases as catalysts revealed that they can be activated by small amounts of water, which all silicone feed

Peter C. Hupfield; Richard G. Taylor

1999-01-01

14

Basicity of some P1 phosphazenes in water and in aqueous surfactant solution.  

PubMed

The pKa values in water and in dilute surfactant solution for 15 ring-substituted phenyl P1 pyrrolidino phosphazenes PhN=P(NC4H8)3 and the phenyl P1 dimethylamino phosphazene PhN=P(NMe2)3 previously studied in acetonitrile (AN) and tetrahydrofuran (THF) are reported. The nonionic surfactant Tween 20 was used for the basicity measurements of some compounds to overcome the solubility problems. Measurements with a control group of phosphazenes in both media were used to validate the use of the obtained pKa values as estimates of aqueous values. The pK(a) values of the studied phosphazenes in aqueous medium vary from 6.82 (2,6-dinitro-) to 12.00 (4-dimethylamino-). The basicity span is 5.18 pKa units. The aqueous pKa values of the P1 phosphazenes were correlated with the respective basicity data in AN and THF and from these correlations the pK(a) values in water for the parent compounds HN=P(NC4H8)3 and HN=P(NMe2)3 were estimated as 13.9 and 13.3. Also a comparison of the basicity of phosphazenes and some guanidines, amines and pyridines was made. In water the parent phosphazenes and guanidines are the strongest of all the groups of bases studied. In AN and THF the parent phosphazenes are clearly the strongest bases followed by guanidines, amines and pyridines which are bracketed between the basicities of phenyl phosphazenes. In the gas phase the phosphazenes for which data are available are clearly more basic than the other compounds referred to here. Comparison of the basicity data of P1 phosphazenes and some guanidines confirms earlier conclusions about the partly ylidic character of the N=P double bond. PMID:16729124

Sooväli, Lilli; Rodima, Toomas; Kaljurand, Ivari; Kütt, Agnes; Koppel, Ilmar A; Leito, Ivo

2006-06-01

15

Synthesis, characterization, and biological-pharmacological evaluation of new phosphazenes bearing dioxybiphenyl and schiff base groups.  

PubMed

A new spirocyclophosphazene, 2,2-bis(2-formylphenoxy)-4,4,6,6-bis[spiro(2',2?-dioxy-1'-1?-biphenylyl)]cyclotriphosphazene (3), was obtained from the reaction of 2,2-dichloro-4,4,6,6-bis[spiro(2',2?-dioxy-1'-1?-biphenylyl)]cyclotriphosphazene (2) with 2-hydroxybenzaldehyde. New phosphazene derivatives bearing Schiff base and dioxybiphenyl groups have been synthesized by the reactions of 3 with different amines. The structures of the compounds were defined by elemental analysis, IR, (1) H, (13) C, and (31) P NMR spectroscopy. All the synthesized compounds were screened for their antibacterial activity against both types of Gram-negative and Gram-positive bacteria. The most potent antibacterial compound of this series was compound 12 which has the low MIC value of 3.75-0.9375?µg/mL. Both minimal inhibitory concentrations (MIC) and inhibition zones were determined in order to monitor the efficacy of the synthesized compounds. New compounds were also screened for anticonvulsant, CNS depressant, and sedative-hypnotic activity. After i.p. injection to mice at doses of 30, 100, and 300?mg/kg body weight phosphazenes were examined in the maximal electroshock-induced seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. The neurotoxicity was assessed using the rotorod method. Compounds 4, 5, and 11 were found to be active in both MES screen and scPTZ screen at 0.5?h. All except 12 showed more than 44% decrease in locomotor activity after 1?h of compound administration via actophotometer screen. CNS-depressant activity screened with the help of the forced swim method resulted in some potent compounds. Except for 7 and 12 other tested compounds were found to exhibit potent CNS depressants activity as indicated by increased immobility time. PMID:22415712

Cil, Erol; Tanyildizi, Mehmet Ali; Ozen, Furkan; Boybay, Mustafa; Arslan, Mustafa; Gorgulu, Ahmet Orhan

2012-06-01

16

Phosphorus-nitrogen compounds: Part 28. Syntheses, structural characterizations, antimicrobial and cytotoxic activities, and DNA interactions of new phosphazenes bearing vanillinato and pendant ferrocenyl groups  

NASA Astrophysics Data System (ADS)

The gradually Cl replacement reactions of spirocyclic mono (1 and 2) and bisferrocenyl cyclotriphosphazenes (3-5) with the potassium salt of 4-hydroxy-3-methoxybenzaldehyde (potassium vanillinate) gave mono (1a-5a), geminal (gem-1b-5b), non-geminal (cis-1b, cis-5b and trans-2b-5b), tri (1c-5c) and tetra-substituted phosphazenes (1d-5d). Some phosphazenes have stereogenic P-center(s). The chirality of 4c was verified using chiral HPLC column. Electrochemical behaviors were influenced only by the number of ferrocene groups, but not the length of the amine chains and the substituent(s). The structures of the new phosphazenes were determined by FTIR, MS, 1H, 13C and 31P NMR, HSQC and HMBC spectral data. The solid-state structures of cis-1b and 4d were examined by single crystal X-ray diffraction techniques. The twelve phosphazene derivatives were screened for antimicrobial activity and the compounds 5a, cis-1b and 2c exhibited the highest antibacterial activity against G(+) and G(-) bacteria. In addition, it was found that overall gem-1b inhibited the growth of Mycobacterium tuberculosis. The compounds 1d, 2d and 4d were tested in HeLa cancer cell lines. Among these compounds, 2d had cytotoxic effect on HeLa cell in the first 48 h. Moreover, interactions between compounds 2a, gem-1b, gem-2b, cis-1b, 2c, 3c, 4c, 5c, 1d, 2d and 4d, and pBR322 plasmid DNA were investigated.

Tümer, Yasemin; Asmafiliz, Nuran; K?l?ç, Zeynel; Hökelek, Tuncer; Yasemin Koç, L.; Aç?k, Leyla; Yola, Mehmet Lütfi; Solak, Ali Osman; Öner, Ya?mur; Dündar, Devrim; Yavuz, Makbule

2013-10-01

17

Stabilization of ketone and aldehyde enols by formation of hydrogen bonds to phosphazene enolates and their aldol products.  

PubMed

Solution properties of enolates generated using the phosphazene (Schwesinger) base P4-tBu were investigated by NMR spectroscopy. With a full equivalent of base the benzyl ketones 1a and 1b, the acetophenone 2, the arylacetaldehyde 1c, and the methyl arylacetate 1d formed the expected "naked" (P4H+) enolates 3 and 7. However, at a half-equivalent of base the ketones 1a and 1b as well as the aldehyde 1c formed solutions of stable hydrogen-bonded dimeric (enol-enolate) structures (4). The acetophenone 2, on the other hand, forms only traces of the H-bonded dimer 8 during deprotonation of 2. The thermodynamic product was the isomeric self-aldol condensation product 12. The mechanism of this condensation was elucidated by low temperature rapid-injection (RI) NMR spectroscopy. Solutions of 8 stable enough for NMR characterization could be transiently generated by semiprotonation of the enolate 7 with HCl.OEt2 at -130 degrees C using RINMR. The ester enolate 1d gave no trace of 4d even on a time scale as short as a few seconds at -130 degrees C either during the semideprotonation of 1d, or during semiprotonation of the enolate 3d. Long-lived solutions of the enols derived from 1a, 1b, 1c, and 2 (but not 1d) could be produced by full protonation of the phosphazene enolates with HCl.OEt2 at low temperature. PMID:18593122

Kolonko, Kristopher J; Reich, Hans J

2008-07-30

18

Control of Chemical, Thermal, and Gas Transport Properties in Dense Phosphazene Polymer Membranes.  

SciTech Connect

Polyphosphazenes are hybrid polymers having organic pendant groups attached to an inorganic backbone. Phosphazene polymers can be tailored to specific applications through the attachment of a variety of different pendant groups to the phosphazene backbone. Applications for which these polymers have proven useful include solid polymer electrolytes for batteries and fuel cells, as well as, membranes for gas and liquid separations. In past work, phosphazene polymers have been synthesized using mixtures of pendant groups with differing chemical affinities. Specific ratios of hydrophobic and hydrophilic pendant groups were placed on the phosphazene backbone with a goal of demonstrating control of solubility, and therefore chemical selectivity. In this work, a series of phosphazene homo-polymers were synthesized having varying amounts of hydrophobic and hydrophilic character on each individual pendant group. Polymers were synthesized having a hydrophilic portion next to the polymer backbone and the hydrophobic portion on the terminal end of the pendant group. The effects of these combined hydrophobic/hydrophilic pendant groups on polymer morphology and gas transport properties are presented. The following data will be addressed: thermal characterization, pure gas permeability on seven gases (Ar, H2, O2, N2, CO2, and CH4 ), and ideal selectivity for the gas pairs: O2/N2, H2/CO2, CO2/H2, CO2/CH4 and CO2/N2.

Christopher J. Orme; Frederick F. Stewart; Mark L. Stone; Mason K. Harrup; Thomas A. Luther; Eric S. Peterson

2005-10-01

19

A crystallographically isolated dimeric hydrolyzed chloro-phosphazene dianion  

PubMed Central

Single crystals of the title compound bis[bis­(1-ethyl-3-methyl-imidazol-2-yl­idene)silver(I)] 1,5,5,7,11,11-hexa­chloro-2,8-di­oxa-4,6,10,12,13,14-hexa­aza-1?5,3,5?5,7?5,9,11?5-hexa­phospha­tricyclo­[7.3.1.13,7]tetra­deca-1(13),4,7(14),10-tetra­ene-6,12-diide 3,9-dioxide, [Ag(C6H10N2)2](Cl6N6O4P6)0.5, were isolated from the reaction of the silver N-heteocyclic carbene complex [Ag(C6H10N2)2]Cl and hexa­chloro­cyclo­triphos­phazene [NPCl2]3 in the presence of water. The asymmetric unit contains one silver carbene cation with the carbene ligands bound to the Ag(I) in an almost linear arrangement and one half of a hydrolyzed phosphazene dianion. The second cation and additional half of the anion are generated by an inversion center.

Panzner, Matthew J.; Youngs, Wiley J.; Tessier, Claire A.

2009-01-01

20

Water Transport Polymers -- Structure/Property Relationships of a Series of Phosphazene Polymers  

SciTech Connect

A study was undertaken to explore the water passing properties of a series of phosphazene polymers versus attached pendant group structure. Pendant groups containing different numbers ethyleneoxy groups were synthetically attached to the backbone of phosphazene polymers. Phosphazene polymers facilitate these types of studies because during their synthesis the polymer backbone is formed first and then the desired pendant groups are attached through nucleophilic substitution. For these studies, four polymer series were synthesized and tested for their water passing properties. The polymers contained different amounts of ethyleneoxy units. Two polymer families were synthesized and compared in this work. The critical difference in these two series is that one contained pendant groups with aromatic rings, in addition to the oligioethyleneoxy moieties, while the other does not. Polymers with phenyl group-containing pendant groups exhibited poor water permeability if they possessed fewer than six ethyleneoxy units. Polymers with more than six ethyleneoxy units inserted between the phenyl ring (tail) and the polymeric backbone, exhibited reasonable water permeability. Two additional series of mixed pendant group polymers were synthesized and the water passing properties of the phosphazenes varied in proportion to the hydrophilic to hydrophobic balance induced by each individual pendant group. A final study, polymers with shorter pendant groups, is shown to fully demonstrate the effect of pendant group on water permeability. These studies suggest that the polyphosphazenes may be tailored for specific water passing applications.

Christopher J. Orme; Eric S. Peterson; William F. Bauer; Frederick F. Stewart; Mason K. Harrup; Thomas A. Luther; John R. Klaehn; John E. Wey

2010-01-01

21

Using density functional theory to interpret the infrared spectra of flexible cyclic phosphazenes.  

PubMed

The cyclic phosphazene trimer P(3)N(3)(OCH(2)CF(3))(6)and the related cyclic tetramer P(4)N(4)(OCH(2)CF(3))(8) have been synthesized, isolated and their vapor-phase absorption spectra recorded at moderate resolution using an FTIR spectrometer. The interpretation of these spectra is achieved primarily by comparison with the results of high-precision density functional calculations, which enable the principal absorption features to be assigned and conclusions to be drawn regarding the geometries and conformations adopted by both molecules. These in turn allow interesting comparisons to be made with analogous cyclic halo-phosphazenes (such as P(3)N(3)Cl(6)) and other related ring compounds. The highly flexible nature of the two cyclic phosphazenes precludes a complete theoretical study of their potential energy hypersurfaces and a novel alternative approach involving the analysis of a carefully selected subset of the possible molecular conformations has been shown to produce satisfactory results. The two cyclic phosphazene oligomers have been proposed as the major low-to-medium temperature pyrolysis products of the parent polyphosphazene (PN(OCH(2)CF(3))(2))(n), and the identification of vibrational absorption features characteristic of each molecule will enable future studies to test the validity of this proposition. PMID:22260404

King, Adrian K; Plant, David F; Golding, Peter; Lawson, Michael A; Davies, Paul B

2012-03-01

22

Phenalene-phosphazene complexes: Effect of exocyclic charge densities on the cyclotriphosphazene ring system  

SciTech Connect

The synthesis and properties of a new series of 1,9-diamino-substituted phenalene complexes of the cyclotriphosphazene ring system is described. One of the compounds is shown to be amphoteric, and this behavior allows an examination of the response of the phosphazene linkage to variations in exocyclic charge density at the spiro center in a plane perpendicular to the cyclotriphosphazene ring system. /sup 31/P NMR spectroscopy indicates that substituent lone pairs with this orientation are not effective in long-range delocalization within the phosphazene linkage (in accord with their theoretical model of spiro delocalization). An x-ray crystal structure of one compound (7) identifies the presence of clathrated molecules of chloroform together with doubly hydrogen-bonded pairs of the phenalene-phosphazene complexes in the lattice. Crystal data for 7 (C/sub 13/H/sub 8/Cl/sub 4/N/sub 5/P/sub 3/ /times/ CHCl/sub 3/): monoclinic space group P2/sub 1//c, a = 12.401 (4) /angstrom/, b = 28.404 (6) /angstrom/, c = 12.962 (3) /angstrom/, /beta/ = 91.76 (2)/degree/, V = 4564 (2) /angstrom//sup 3/, Z = 8, R = 0.050 for 4525 reflections. 24 references, 3 figures, 7 tables.

Haddon, R.C.; Chichester-Hicks, S.V.; Mayo, S.L.

1988-06-01

23

Inorganic–organic hybrid polymers with pendent sulfonated cyclic phosphazene side groups as potential proton conductive materials for direct methanol fuel cells  

Microsoft Academic Search

A synthetic method is described to produce a proton conductive polymer membrane with a polynorbornane backbone and inorganic–organic cyclic phosphazene pendent groups that bear sulfonic acid units. This hybrid polymer combines the inherent hydrophobicity and flexibility of the organic polymer with the tuning advantages of the cyclic phosphazene to produce a membrane with high proton conductivity and low methanol crossover

Shih-To Fei; Richard M. Wood; David K. Lee; David A. Stone; Hwei-Liang Chang; Harry R. Allcock

2008-01-01

24

Surface Reaction of Poly(Bis(Trifluoroe thoxy)Phosphazene) Films by BasicHydrolysis. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

A novel surface reaction of a fluoroalkoxyphosphazene polymer is reported. Film of poly(bis(trifluoroethoxy) phosphazene), underwent surface hydrolysis when treated for 0.15 min with 8 M aqueous sodium hydroxide in the presence of 0.05 M tetra-n-butylammo...

H. R. Allcock J. S. Rutt R. J. Fitzpatrick

1991-01-01

25

Syntheses and Structures of Cyclic and Short-Chain Linear Phosphazenes Bearing 4-Phenylphenoxy Side Groups. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

High polymeric phosphazenes form a class of inorganic/organic macromolecules that possess a wide rage of unusual properties. The type of side group attached to the polyphosphazene chain has a powerful effect on the physical and chemical characteristics. A...

H. R. Allcock D. C. Ngo M. Parvez R. R. Whittle W. J. Birdsall

1991-01-01

26

On the Contributions to the Materials Science Aspects of Phosphazene Chemistry by Professor Christopher W. Allen: The One-Pot Synthesis of Linear Polyphosphazenes  

SciTech Connect

The wide range of applications for the phosphazene compounds has stimulated a major research effort involving several industrial, academic, and national laboratories over the past 40 years. One of Professor Allen’s research areas was to establish fundamental synthetic methods for the commercial preparation of phosphazene polymers, investigate their properties, and develop useful products. In this paper we review some of the materials science aspects of Professor Allen’s research including recent advances on the preparation and polymerization of Cl3PNP(O)Cl2. This work, in particular, has led to a route for the “one-pot” synthesis of stable linear poly(organophosphazenes) as demonstrated through the formation of poly[bis-(2-methoxyethoxyethoxy)phosphazene] (MEEP) and a phosphazene heteropolymer (HPP) containing a balance of hydrophilic and hydrophobic components that allow for control and molecular affinities.

Eric S. Peterson; Thomas A. Luther; Mason K. Harrup; John R. Klaehn; Mark L. Stone; Christopher J. Orme; Frederick F. Stewart

2007-06-01

27

Phosphazene Based Additives for Improvement of Safety and Battery Lifetimes in Lithium-Ion Batteries  

SciTech Connect

There need to be significant improvements made in lithium-ion battery technology, principally in the areas of safety and useful lifetimes to truly enable widespread adoption of large format batteries for the electrification of the light transportation fleet. In order to effect the transition to lithium ion technology in a timely fashion, one promising next step is through improvements to the electrolyte in the form of novel additives that simultaneously improve safety and useful lifetimes without impairing performance characteristics over wide temperature and cycle duty ranges. Recent efforts in our laboratory have been focused on the development of such additives with all the requisite properties enumerated above. We present the results of the study of novel phosphazene based electrolytes additives.

Mason K Harrup; Kevin L Gering; Harry W Rollins; Sergiy V Sazhin; Michael T Benson; David K Jamison; Christopher J Michelbacher

2011-10-01

28

Fluorinated phosphazene co-solvents for improved thermal and safety performance in lithium-ion battery electrolytes  

NASA Astrophysics Data System (ADS)

The safety of lithium-ion batteries is coming under increased scrutiny as they are being adopted for large format applications especially in the vehicle transportation industry and for grid-scale energy storage. The primary short-comings of lithium-ion batteries are the flammability of the liquid electrolyte and sensitivity to high voltage and elevated temperatures. We have synthesized a series of non-flammable fluorinated phosphazene liquids and blended them with conventional carbonate solvents. While the use of these phosphazenes as standalone electrolytes is highly desirable, they simply do not satisfy all of the many requirements that must be met such as high LiPF6 solubility and low viscosity, thus we have used them as additives and co-solvents in blends with typical carbonates. The physical and electrochemical properties of the electrolyte blends were characterized, and then the blends were used to build 2032-type coin cells. We have evaluated the performance of the electrolytes by determining the physical properties, thermal stability, electrochemical window, cell cycling data, and the ability to form solid electrolyte interphase (SEI) films. This paper presents our most recent results on a new series of fluorinated cyclic phosphazene trimers, the FM series, which has exhibited numerous beneficial effects on battery performance, lifetimes, and safety aspects.

Rollins, Harry W.; Harrup, Mason K.; Dufek, Eric J.; Jamison, David K.; Sazhin, Sergiy V.; Gering, Kevin L.; Daubaras, Dayna L.

2014-10-01

29

Surface Functionalization with Phosphazenes: Part 6. Modification of Polyethylene Co -Polyvinylalcohol Copolymer Surface Plates with Fluorinated Alcohols and Azobenzene Derivatives Using Chlorinated Phosphazenes as Coupling Agents  

Microsoft Academic Search

In this paper we describe a two-step surface modification process of poly(ethylene-co-vinyl alcohol) by exploiting hexachlorocyclophosphazene and poly(dichlorophosphazene) as coupling agents. Part of the P–Cl\\u000a groups of the chlorophosphazenes is first reacted with the surface hydroxylic groups of the substrate to form covalent P–O–C\\u000a bonds, the remaining being utilized for successive substitution reactions with different nucleophiles (i.e. 2,2,2-trifluoroethanol,\\u000a heptadecafluorononanol and

Roberto Milani; Mario Gleria; Silvia Gross; Roger De Jaeger; Ahmed Mazzah; Leon Gengembre; Martine Frere; Charafeddine Jama

2008-01-01

30

Plasma surface functionalization of poly[bis(2,2,2-trifluoroethoxy)phosphazene] films and nanofibers.  

PubMed

Polyphosphazenes are a class of hybrid organic-inorganic macromolecules with high thermo-oxidative stability and good solubility in many solvents. Fluoroalkoxy phosphazene polymers also have high surface hydrophobicity. A method is described to tune this surface property while maintaining the advantageous bulk materials characteristics. The polyphosphazene single-substituent polymer, poly[bis(2,2,2-trifluoroethoxy)phosphazene], with flat film, fiber mat, or bead mat morphology was surface functionalized using an atmospheric plasma treatment with oxygen, nitrogen, methane, or tetrafluoromethane/hydrogen gases. Surface chemistry changes were detected by static water contact angle (WCA) measurements as well as X-ray photon spectroscopy (XPS). It was found that changes in the WCA of as much as 150 degrees occurred, accompanied by shifts in the ratio of elements on the polymer surface as detected by XPS. Overall this plasma technique provides a convenient method for the generation of specific surface characteristics while maintaining the hydrophobicity of the bulk material. PMID:17590030

Allcock, Harry R; Steely, Lee B; Kim, Seong H; Kim, Jeong H; Kang, Bang-Kwon

2007-07-17

31

Study of the T(1) Transition of Poly(bis(trifluoroethoxy)phosphazene) (PBFP) Using Solid-State Nuclear Magnetic Resonance Spectroscopy.  

National Technical Information Service (NTIS)

In situ solid state variable temperature NMR measurements have been made on Poly(bis(trifluoroethoxy)phosphazene above and below the first order thermotropic transition, T(1). A single mobile ordered 2D phase exists above T(1). Below T(1) and at room temp...

J. H. Magill S. G. Young

1989-01-01

32

Characterization of 2-(2-Methoxyethoxy)ethanol Substituted Phosphazene Polymers Using Pervaporation, Solubility Parameters and Sorption Studies  

SciTech Connect

Two linear phosphazene polymers were synthesized with differing amounts of hydrophilic 2-(2-methoxyethoxy)ethanol (MEE) and hydrophobic 4-methoxyphenol (MEOP) substituted on the backbone. These high polymers were cast into membranes and their permeability to water, methanol, ethanol, and 2-propanol was evaluated as a function of temperature. An additional polymer with a low content of MEE was studied for water permeation and was characterized by trace flux. At higher levels of MEE on the backbone, fluxes of all solvents increased. Solubility also was found to increase with increasing MEE content for all solvents except water. Unexpectedly, water was found to be less soluble in the higher MEE polymer, although higher membrane fluxes were observed. Diffusion coefficients showed the following trend: methanol 2-propanol > ethanol water. Finally, the affinity of solvents and polymers was discussed in terms of Hansen solubility parameters.

Orme, Christopher Joseph; Klaehn, John Ray; Harrup, Mason Kurt; Lash, Robert Paul; Stewart, Frederick Forrest

2005-05-01

33

Novel spirocyclic phosphazene-based epoxy resin for halogen-free fire resistance: synthesis, curing behaviors, and flammability characteristics.  

PubMed

A novel halogen-free fire resistant epoxy resin with pendent spiro-cyclotriphosphazene groups was designed and synthesized via a three-step synthetic pathway. The chemical structures and compositions of spiro-cyclotriphosphazene precursors and final product were confirmed by (1)H, (13)C, and (31)P NMR spectroscopy, mass spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy. The thermal curing behaviors of the synthesized epoxy resin with 4,4'-diamino-diphenylmethane, 4,4'-diamino-diphenyl sulfone, and novolac as hardeners were investigated by differential scanning calorimetry (DSC), and the curing kinetics were also studied under a nonisothermal condition. The evaluation of the thermal properties demonstrated that these thermosets achieved a good thermal resistance due to their high glass transition temperatures more than 150 °C, and also gained high thermal stabilities with high char yields. The flammability characteristics of the spirocyclic phosphazene-based epoxy thermosets cured with these three hardeners were investigated on the basis of the results obtained from the limiting oxygen index (LOI) and UL-94 vertical burning experiments as well as the analysis of the residual chars collected from the vertical burning tests. The high LOI values and UL-94 V-0 classification of these epoxy thermosets indicated that the incorporation of phosphazene rings into the backbone chain imparts nonflammability to the epoxy resin owing to the unique combination of phosphorus and nitrogen following by a synergistic effect on flame retardancy. The epoxy resin obtained in this study is a green functional polymer and will become a potential candidate for fire- and heat-resistant applications in electronic and microelectronic fields with more safety and excellent performance. PMID:22833687

Sun, Jian; Wang, Xiaodong; Wu, Dezhen

2012-08-01

34

Poly[di(sodium carboxylatoethylphenoxy)phosphazene] (PCEP) is a potent enhancer of mixed Th1/Th2 immune responses in mice immunized with influenza virus antigens.  

PubMed

We investigated the ability of a novel polyphosphazene polyelectrolyte, poly[di(sodium carboxylatoethylphenoxy)phosphazene] (PCEP) to enhance antigen-specific immune responses. BALB/c mice were immunized once subcutaneously with either bovine serum albumin (BSA) or influenza virus X:31 antigen alone, or in combination with PCEP, or either of the adjuvants poly[di(sodium carboxylatophenoxy)phosphazene] (PCPP) and alum. Both PCEP and PCPP significantly enhanced serum antigen-specific total IgG, IgG1 and IgG2a antibody titers, and these responses were highest in PCEP-immunized mice. Alum induced only a modest enhancement of antibody responses. Reducing the dose of X:31 antigen by 25-fold had no effect on antibody responses in mice immunized with PCPP and PCEP, but resulted in reduced titers in those immunized with alum. Analysis of X:31 antigen-specific cytokines revealed that alum and PCPP were associated with a predominantly IL-4 response. In contrast, PCEP was associated with production of both IFNgamma and IL-4. We conclude that PCEP is a potent enhancer of antigen-specific Th1 and Th2 immune responses and is a promising adjuvant for vaccine applications. PMID:17140708

Mutwiri, George; Benjamin, Ponn; Soita, Henry; Townsend, Hugh; Yost, Richard; Roberts, Bryan; Andrianov, Alexander K; Babiuk, Lorne A

2007-01-26

35

Derivatives  

NSDL National Science Digital Library

Murray Bourne developed the Interactive Mathematics site while working as a mathematics lecturer at Ngee Ann Polytechnic in Singapore. The site contains numerous mathematics tutorials and resources for students and teachers alike. This specific page is focused on differentiation, or finding derivatives. Bourne walks users through an introduction to differentiation and limits, and then moves on to more specific applications like rate of change, derivatives of polynomials, and differentiating powers of a function. Each topic includes graphs and interactive materials designed to aid users in understanding the presented concepts. The information here is presented in a clear, straightforward manner that is appropriate for introductory and advanced calculus students alike.

Bourne, Murray

2008-04-22

36

Derivate  

NSDL National Science Digital Library

In this activity, students input functions in order to calculate the derivative and tangent line of that function. This activity allows students to explore tangent lines of various functions. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

37

Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid)  

PubMed Central

Previously we demonstrated the ability of ethyl glycinato substituted polyphosphazenes to neutralize the acidic degradation products and control the degradation rate of poly(lactic acid-glycolic acid) by blending. In this study, blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA50PhPh50) and 85:15 poly(lactic acid-glycolic acid) (PLAGA) were prepared using a mutual solvent approach. Three different solvents, methylene chloride (MC), chloroform (CF) and tetrahydrofuran (THF) were studied to investigate solvent effects on blend miscibility. Three different blends were then fabricated at various weight ratios namely 25:75 (BLEND25), 50:50 (BLEND50), and 75:25 (BLEND75) using THF as the mutual solvent. The miscibility of the blends was evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Among these, BLEND25 was miscible while BLEND50 and BLEND75 were partially miscible. Furthermore, BLEND25 formed apatite layers on its surface as evidenced in a biomimetic study performed. These novel blends showed cell adhesion and proliferation comparable to PLAGA. However, the PNEA50PhPh50 component in the blends was able to increase the phenotypic expression and mineralized matrix synthesis of the primary rat osteoblasts (PRO) in vitro. Blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA50PhPh50) and 85:15 poly(lactic acid-glycolic acid) (PLAGA) are promising biomaterials for a variety of musculoskeletal applications.

Deng, Meng; Nair, Lakshmi S.; Nukavarapu, Syam P.; Kumbar, Sangamesh G.; Jiang, Tao; Krogman, Nicholas R.; Singh, Anurima; Allcock, Harry R.; Laurencin, Cato T.

2007-01-01

38

Osteocompatibility evaluation of poly(glycine ethyl ester-co-alanine ethyl ester)phosphazene with honeycomb-patterned surface topography.  

PubMed

Biodegradable amino acid ester-substituted polyphosphazenes are unique biomaterials for tissue engineering. Considering the surface properties as topography and chemical composition having vital roles in regulating cellular response, in this study, a kind of micropatterned polyphosphazene films were prepared and subjected to osteoblasts culture. Briefly, poly(glycine ethyl ester-co-alanine ethyl ester)phosphazene (PGAP) was synthesized, and its solution in chloroform was cast under high (80%) or low (20%) environmental humidity. Honeycomb-patterned or flat PGAP films were resulted. By analyzing with scanning electron microscope, atomic force microscope, X-ray photoelectron spectroscope, and water contact angle measurement, the honeycomb-patterned PGAP films demonstrated higher surface roughness, phosphorous and nitrogen content, and hydrophilicity than the flat one. Although the initial cell attachment and proliferation on PGAP films were inferior to those on conventional poly(lactic-co-glycolic acid) films, P-containing PGAP was a sort of bone-binding bioactive polymer. With these alternations, honeycomb-patterned PGAP films had accordingly enhanced protein adsorption and apatite deposition in simulated body fluid and showed great advantages in promoting osteogenous differentiation. The results suggested a potential way to make polyphosphazenes as good choices for bone tissue regeneration by increasing their surface roughness and phosphorous content. PMID:22733644

Duan, Shun; Yang, Xiaoping; Mao, Jifu; Qi, Bing; Cai, Qing; Shen, Hong; Yang, Fei; Deng, Xuliang; Wang, Shenguo

2013-02-01

39

Miscibility and in vitro osteocompatibility of biodegradable blends of poly[(ethyl alanato) (p-phenyl phenoxy) phosphazene] and poly(lactic acid-glycolic acid).  

PubMed

Previously we demonstrated the ability of ethyl glycinato substituted polyphosphazenes to neutralize the acidic degradation products and control the degradation rate of poly(lactic acid-glycolic acid) (PLAGA) by blending. In this study, blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA(50)PhPh(50)) and 85:15 PLAGA were prepared using a mutual solvent approach. Three different solvents, methylene chloride (MC), chloroform (CF) and tetrahydrofuran (THF) were studied to investigate solvent effects on blend miscibility. Three different blends were then fabricated at various weight ratios namely 25:75 (BLEND25), 50:50 (BLEND50), and 75:25 (BLEND75) using THF as the mutual solvent. The miscibility of the blends was evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Among these, BLEND25 was miscible while BLEND50 and BLEND75 were partially miscible. Furthermore, BLEND25 formed apatite layers on its surface as evidenced in a biomimetic study performed. These novel blends showed cell adhesion and proliferation comparable to PLAGA. However, the PNEA(50)PhPh(50) component in the blends was able to increase the phenotypic expression and mineralized matrix synthesis of the primary rat osteoblasts (PRO) in vitro. Blends of high strength PNEA(50)PhPh(50) and 85:15 PLAGA are promising biomaterials for a variety of musculoskeletal applications. PMID:17942150

Deng, Meng; Nair, Lakshmi S; Nukavarapu, Syam P; Kumbar, Sangamesh G; Jiang, Tao; Krogman, Nicholas R; Singh, Anurima; Allcock, Harry R; Laurencin, Cato T

2008-01-01

40

Phosphazene Membranes for Gas Separations.  

National Technical Information Service (NTIS)

A polyphosphazene having a glass transition temperature (T(sub g)) of approximately -20 degrees C. or less. The polyphosphazene has at least one pendant group attached to a backbone of the polyphosphazene, whereinthe pendant group has no halogen atoms. In...

C. J. Orme, F. F. Stewart, M. K. Harrup, T. A. Luther

2004-01-01

41

Asymmetric Mannich reaction between (S)-N-(tert-butanesulfinyl)-3,3,3-trifluoroacetaldimine and malonic acid derivatives. Stereodivergent synthesis of (R)- and (S)-3-amino-4,4,4-trifluorobutanoic acids.  

PubMed

Inorganic as well as organic base catalysis was found to be effective for diastereoselective Mannich additions of malonic acid derivatives to (SS)-N-(tert-butanesulfinyl)-3,3,3-trifluoroacetaldimine. In the presence of catalytic amounts of inorganic bases, n-BuLi or DMAP, the reaction gives the corresponding (R,SS)-?-aminomalonates in good yield and with diastereoselectivity up to 9/1 dr. In contrast, phosphazene bases favour the formation of the (S,SS)-diastereomer with selectivities as high as 99/1. Simple choosing of an appropriate base catalyst for the Mannich addition reaction allowed us to obtain enantiomerically pure (R)- or (S)-configured 3-amino-4,4,4-trifluorobutanoic acids after hydrolysis and decarboxylation of the corresponding ?-aminomalonates. PMID:24445698

Shibata, Norio; Nishimine, Takayuki; Shibata, Naoyuki; Tokunaga, Etsuko; Kawada, Kosuke; Kagawa, Takumi; Aceña, José Luis; Sorochinsky, Alexander E; Soloshonok, Vadim A

2014-03-01

42

Derivatives Page  

NSDL National Science Digital Library

Derivatives are financial securities whose value is derived from another "underlying" financial security. Options, futures, swaps, swaptions, and structured notes are all examples of derivative securities. Derivatives can be used in hedging, protecting against financial risk, or can be used to speculate on the movement of commodity or security prices, interest rates, or the levels of financial indices. The valuation of derivatives makes use of the statistical mathematics of uncertainty. With links to related articles. See also Derivatives Concepts A-Z, glossary of derivatives-related terminology designed to make the other articles in the Financial Pipeline's Derivatives section easier to understand.

2007-03-22

43

Phosphorus-nitrogen compounds. Part 20: Fully substituted spiro-cyclotriphosphazenic lariat (PNP-pivot) ether derivatives  

NASA Astrophysics Data System (ADS)

The condensation reactions of partly substituted spiro-cyclotriphosphazenic lariat (PNP-pivot) ethers, N 3P 3[( o-NHPhO) 2R]Cl 4 [where R = -CH 2CH 2- ( 1) and -CH 2CH 2OCH 2CH 2- ( 2)] with morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) produce fully substituted morpholino ( 3 and 4) and 1,4-dioxa-8-azaspiro[4,5]deca ( 5 and 6) phosphazenes. These are the new examples of the spiro-cyclophosphazenic lariat ether derivatives with N 2O x ( x = 2 and 3) donor type containing 11- and 14-membered macrocycles. The solid state structures of 3, 5 and 6 have been determined by X-ray diffraction techniques. Compound 3 has intermolecular N-H…O hydrogen bond, compound 5 has intra- and intermolecular N-H…O hydrogen bonds, while compound 6 has intramolecular N-H…O and O-H…N and intermolecular N-H…O and O-H…O hydrogen bonds. The correlations of the endocyclic ( ?) and exocyclic ( ?') NPN bond angles with ?P spiro values are investigated. The structural investigations of 3- 6 have been verified by elemental analyses, MS, FTIR, 1H, 13C and 31P NMR, DEPT and HETCOR techniques.

Okumu?, Aytu?; Bilge, Selen; K?l?ç, Zeynel; Öztürk, Asl?; Hökelek, Tuncer; Y?lmaz, Filiz

2010-08-01

44

Constrained-geometry bisphosphazides derived from 1,8-diazidonaphthalene: synthesis, spectroscopic characteristics, structural features, and theoretical investigations.  

PubMed

Investigations on the Staudinger reaction between 1,8-diazidonaphthalene and phosphorous(III) building blocks, a key step in the synthesis of superbasic bisphosphazene proton sponges, yielded a set of bisphosphazides with a constrained geometry 1,8-disubstituted naphthalene backbone. This compound class has attracted our interest not only due to their surprisingly high stability, but in particular because of their theoretically predicted basicity in the range of their bisphosphazene analogues that can be referred to the constrained geometry interaction of two highly basic nitrogen atoms. Eleven new bisphosphazides bearing simple P-amino groups as well as P-guanidino substituents, azaphosphatrane moieties, P2 building blocks, or chiral P-amino substituents derived from L-proline are presented. They were studied concerning their spectroscopic properties and partly also their chromophoric and structural features. In the case of the pyrrolidino-substituted TPPN(2N2) (TPPN = 1,8-bis(trispyrrolidinophosphazenyl)naphthalene), the stepwise nitrogen elimination is investigated theoretically and experimentally, which led to the isolation and structural characterization of TPPN(1N2) bearing a phosphazide and a phosphazene functionality in one molecule. Attempts to protonate the obtained bisphosphazides and to prove the computationally predicted pKBH(+) values through NMR titration reactions resulted in their decay, which again was rationalized by theoretical calculations. Altogether we present the so far most extensive spectroscopic, structural and theoretical investigation of constrained geometry bisphosphazides and their Brønsted and Lewis basic properties. PMID:24687589

Kögel, Julius F; Abac?lar, Nuri C; Weber, Felicia; Oelkers, Benjamin; Harms, Klaus; Kova?evi?, Borislav; Sundermeyer, Jörg

2014-05-12

45

Discrete Derivatives  

NASA Astrophysics Data System (ADS)

The method of finite-differences is an important technique used to obtain numerical solutions to differential equations. Critical to the construction of such discrete models is how should the discrete representations of the derivatives be formulated? A prior, there exists many possibilities; examples, include the forward- and backward-Euler expressions, as well as various central-differences. However, it has become clear in recent years that the order of the discrete derivative must be the same as the particular order of the derivative appearing in the differential equation. If not, numerical instabilities will appear; these are solutions to the discrete equations that do not correspond to any solutions of the original differential equations. We show that discrete representations of first-derivatives can be constructed such that the elementary numerical instabilities do not occur. Our method generalizes the usual calculus based definition of the derivative. The general scalar ODE is used to illustrate our method.

Mickens, Ronald E.

2000-11-01

46

Dielectric and absorbate effects on the optical properties of phosphazenes  

SciTech Connect

The optical response of polyphosphazenes can be directly related to the {pi} (out-of-plane) and {pi}{prime} (in-plane) bonding interactions intrinsic to the electronic structure of these materials. Altering this structure either by hydrogen bonding or absorbate effects, affects both the linear and nonlinear optical susceptibilities. In this paper, we have performed electronic structure calculations on the cyclic molecules, P{sub 3}N{sub 3}(NHCH{sub 3}){sub 6}, P{sub 3}N{sub 3}(SCH{sub 3}){sub 6}, P{sub 3}N{sub 3}(OCH{sub 3}){sub 6} and P{sub 4}N{sub 4}(NHCH{sub 3}){sub 8} as model systems for the polymer. Charge distribution arguments are discussed to explain the influence of a polarizing electric field on the {pi} bonding systems, and are used to suggest methods to enhance their nonlinearities.

Ferris, K.F.; Samuels, W.D.; Morita, Y.; Exarhos, G.J.

1993-12-01

47

Glycopeptide derivatives.  

PubMed

Resistance to glycopeptides in enterococci, which first emerged in the late 1980's and is now widespread mainly in the United States, is posing a serious clinical problem due to the lack of alternative and efficacious therapeutic options, particularly against infections caused by VanA strains that are highly resistant to glycopeptides and almost all other antibiotics. In addition, isolates of Staphylococcus aureus, known as GISA, that are poorly susceptible to vancomycin and teicoplanin have been identified. Thus, there is an urgent need to develop new and more potent glycopeptides that are active against these problematic organisms. The following review will focus on the development of second-generation glycopeptides, namely LY333328 (Eli Lilly) and BI 397 (Biosearch Italia, in license to Versicor for North America), which are currently undergoing clinical trials in humans for their promising activity against VanA enterococci (LY333328), staphylococci (BI 397), and penicillin-resistant pneumococci. Both compounds were identified as the result of chemical programs that were aimed at pursuing activity of vancomycin-like or teicoplanin-like natural glycopeptides against VanA enterococci and multidrug-resistant staphylococci. More recent approaches toward glycopeptides modified in their heptapeptide core are also described. These include compounds in which amino acids 1 and 3 are replaced with other amino acid moieties such as in the modification of the asparagine side chain on residue 3 as well as attempts to change the structure of the heptapeptide backbone in positions that are critical for the molecular interaction with susceptible D-Ala-D-Ala and resistant D-Ala-D-Lactate targets. Covalently linked glycopeptide dimers and vancomycin derivatives in which vancosamine is suitably replaced with other sugar moieties will also be covered. PMID:11562292

Malabarba, A; Ciabatti, R

2001-12-01

48

Phosphorus-nitrogen compounds: Novel fully substituted spiro-cyclophosphazenic lariat (PNP-pivot) ether derivatives. Structures of 4,4,6,6-tetrapyrrolidino-2,2-[3-oxa-1,5-pentane dioxy bis(2-phenylamino)]cyclo-2 ?5,4 ?5,6 ?5-triphosphazene and 4,4,6,6-tetrapyrrolidino-2,2-[1,2-xylylene dioxy bis(2-phenylamino)]cyclo-2 ?5,4 ?5,6 ?5-triphosphazene. Part XI  

NASA Astrophysics Data System (ADS)

The condensation reaction of partly substituted spiro-cyclophosphazenic lariat (PNP-pivot) ethers, N 3P 3[( o-NHPhO) 2R]Cl 4 ( 5- 8), where R=-CH 2CH 2-, -CH 2CH 2CH 2-, -CH 2CH 2OCH 2CH 2-, and -CH 2PhCH 2-, with pyrrolidine have been afforded fully substituted pyrrolidino phosphazene derivatives ( 9- 12) (Scheme). There are the first examples of the spiro-cyclophosphazenic lariat (PNP-pivot) ether ligands with N 2O x-( x=2, 3) donor type containing 11-14 membered macrocycles. The solid state structures of ( 11 and 12) have been determined by X-ray diffraction techniques. Evidently, in the macrocyclic ring of the compound ( 11), there are two three-centered (bifurcate) N-H⋯O/N-H⋯N hydrogen bonds, while compound ( 12) has two intramolecular N-H⋯O bonds. The relative radii of macrocyclic hole sizes of the compounds ( 11 and 12) are 1.25 and 1.10 Å, respectively. The structures of the new compounds ( 9- 12) have also been examined by FTIR, 1H-, 13C-, 31P-NMR, MS and elemental analysis. Compound ( 11) crystallizes in the Pcab space group with a=9.8474(13), b=18.466(2), c=38.9375(19) Å, V=7080.7(14) Å 3, Z=8 and Dx=1.317 g cm -3, while compound ( 12) crystallizes in P-1 space group with a=9.3724(5), b=11.2613(9), c=20.401(2) Å, ?=93.177(8), ?=102.115(7), ?=105.360(5)°, V=2016.0(3) Å 3, Z=2 and Dx=1.268 g cm -3. The structures of ( 11 and 12) consist of nearly planar and non-planar trimeric phosphazene rings with spiro-cyclic bulky N 2O 3 and N 2O 2 macrocycles, respectively.

Bilge, Selen; Özgüç, Bilgehan; Safran, Serap; Demiriz, ?emsay; ??ler, Hikmet; Hayval?, Mustafa; K?l?ç, Zeynel; Hökelek, Tuncer

2005-06-01

49

Derivative Crystal Structures  

Microsoft Academic Search

There exists a class of crystal structures which are derived from others by generalization. These are here designated derivative structures. A special case of derivative structure is the popular ``superstructure.'' The symmetry of a derivative structure is a subgroup of the symmetry of the basic structure. Here the term ``subgroup'' is used in a wider sense than common in mathematical

M. J. Buerger

1947-01-01

50

Preparation of Benzofuran Derivatives.  

National Technical Information Service (NTIS)

The benzofuran derivatives exhibit estrogenic properties and are useful in animal husbandry, particularly as applied to steers which are grown for meat. The benzofuran derivatives are prepared by oxidizing flavylium salts.

L. Jurd

1965-01-01

51

High affinity tamoxifen derivatives  

US Patent & Trademark Office Database

The synthesis of tamoxifen derivatives, most particularly halo, halo alkyl, hydroxy, and amino tamoxifen derivatives is disclosed. The native tamoxifen molecule includes a substituted chemical group positioned on the aliphatic chain of the tamoxifen molecule. Particular tamoxifen derivatives of the invention include chloro, bromo, iodo, fluoro, amino and DTPA tamoxifen derivatives, and corresponding lower alkyl halogenated forms. The halogenated tamoxifen derivatives possess superior binding affinities for estrogen receptor rich tissues, such as uterine tissue and breast tissue, relative to unsubstituted native tamoxifen. Radiolabeled forms of the tamoxifen derivatives may be used as highly specific imaging agents for estrogen receptor rich tissues. The fluoro and bromo tamoxifen derivatives are particularly useful for imaging estrogen receptors by PET whereas the iodinated tamoxifens are particularly useful in imaging estrogen receptors by SPECT. Rapid and efficient methods of preparing the tamoxifen derivatives having high specific activity (>6 Ci/.mu.mol) are also disclosed. Aliphatic chain substituted tamoxifen derivatives are shown to possess greater estrogen receptor binding affinity and more potent tumor cell inhibition than tamoxifen or tamoxifen derivatives substituted at other locations on the molecule (i.e., non-aliphatic chain substituted tamoxifen). The tanioxifen derivatives of the present invention may advantageously be used as anti-cancer therapeutic agents to halt estrogen-receptor positive tumors, such as those of breast and uterine tissue. The present invention also provides a hydrophilic DTPA-tamnoxifen analogue, and uses thereof in imaging estrogen receptor positive ER+ lesions.

2000-08-01

52

Partial Derivatives: Geometric Visualization  

NSDL National Science Digital Library

This write-pair-share activity presents Calculus III students with a worksheet containing several exercises that require them to find partial derivatives of functions of two variables. Afterwards, a series of Web-based animations are used to illustrate the surface of each function, the path of the indicated partial derivative for a specified value of the variable and the value of the derivative at each point along the path.

Rutledge, James

53

Endohedral Metallofullerene Derivatives  

NASA Technical Reports Server (NTRS)

Trimetallic nitride endohedral metallofullerene derivatives and their preparation are described. The trimetallic nitride endohedral metallofullerene derivatives have the general formula A(sub 3-n)X(sub n)@C(sub m)(R) where n ranges from 0 to 3, A and X may be trivalent metals and may be either rare earth metal or group IIIB metals, m is between about 60 and about 200, and R is preferably an organic group. Derivatives where the R group forms cyclized derivatives with the fullerene cage are also described.

Dorn, Harry C. (Inventor); Iezzi, Erick B. (Inventor); Duchamp, James (Inventor)

2008-01-01

54

Acetylenic derivatives of heterocycles  

Microsoft Academic Search

1.The reaction for the catalytic replacement of halogen in the aromatic ring by the acetylenic moiety was extended to imidazole derivatives.2.In this reaction iodine in the 2 position of the imidazole ring is substantially more active than iodine in the 4 position.3.The mono- and diacetylenic derivatives of imidazole with a free acetylenic hydrogen were obtained.

M. S. Shvartsberg; L. N. Bizhan; I. L. Kotlyarevskii

1971-01-01

55

Partial Derivative Visualization Gallery  

NSDL National Science Digital Library

This resource is a small gallery of demos for illustrating partial derivatives geometrically. These animations can be used by instructors in a classroom setting or by students to aid in acquiring a visualization background for partial derivatives. Two file formats, gif and QuickTime files are used for the animations which can be downloaded.

Roberts, Lila F.; Hill, David R.

2004-11-11

56

Teaching Cournot without Derivatives.  

ERIC Educational Resources Information Center

Presents a simple technique for teaching the Cournot model to first-year microeconomic students. Involves demonstrating, without the use of derivatives, that out of all rectangles with a common perimeter, the square has the greatest area. (RLH)

Dufwenberg, Martin

2001-01-01

57

Preparation of Benzofuran Derivatives.  

National Technical Information Service (NTIS)

The benzofuran derivatives exhibit estrogenic properties and may be used in animal husbandry. Coumestrol is synthesized by reacting 2-(2,4-dihydroxyphenyl)-3-carboalkoxy-6-hydroxy benzofuran with a strong acid in the presence of water to cause hydrolysis ...

L. Jurd

1964-01-01

58

Epoxide-derived organosulfates  

NASA Astrophysics Data System (ADS)

Organosulfates (OS) are a significant fraction of secondary organic aerosol (SOA) material in the atmosphere. OS are typically surface-active, and have been suggested to cause surface tension depression in aerosols. Recent field studies suggest that epoxide-derived OS are the most abundant OS type in aerosols. Time-dependent surface tension measurements and Aerosol-CIMS characterization of two epoxides and their organosulfate products are shown. ?-pinene oxide, derived from ?-pinene, shows significant surface tension depression in H2O and ammonium sulfate. Results from cis-2,3-epoxybutane-1,4-diol (BEPOX), a butadiene-derived analog to isoprene-derived epoxydiols, are also shown. In addition, using GAMMA, a photochemical box model using coupled gas- and aqueous-phase chemistry developed in the McNeill laboratory, we show the dominance of epoxide-derived OS formation over other competing OS formation mechanisms, such as radical chemistry, under both high-NOx and low-NOx scenarios.

Schwier, A. N.; Woo, J.; McNeill, V. F.

2011-12-01

59

Semisynthetic Derivatives of Epothilones  

NASA Astrophysics Data System (ADS)

Semisynthetic derivatives of natural products traditionally occupy a prominent space in natural-product-based drug discovery (1, 2). As many biologically active natural products exhibit a high degree of structural complexity (3), the chemical derivatization of material isolated from natural sources often represents the only feasible means (or at least the only economically viable approach) to explore structure-activity-relationships (SAR) and to produce analogs with more favorable pharmacokinetic and pharmacological properties than the natural product lead. Examples of clinically important drugs that are semisynthetic derivatives of natural products exist in virtually all disease areas (1, 2); in the treatment of cancer this includes compounds such as etoposide or teniposide (derived from podophyllotoxin) (4-6), irinotecan and topotecan (derived from camptothecin) (7-9), or docetaxel (derived from 10-deacetylbaccatin III) (10, 11). Even for taxol (11), which is a natural product (12), the sustained supply of sufficient quantities of material for widespread clinical use could only be secured through the development of a semisynthetic production process from another natural product, namely, 10-deacetylbaccatin III (13). In light of these facts, it is not surprising that semisynthesis approaches have also featured prominently in the elucidation of the SAR for epothilones and in the discovery of a number of clinical development candidates.

Altmann, Karl-Heinz

60

Myeloid derived suppressor cells  

PubMed Central

The goal of achieving measurable response with cancer immunotherapy requires counteracting the immunosuppressive characteristics of tumors. One of the mechanisms that tumors utilize to escape immunosurveillance is the activation of myeloid derived suppressor cells (MDSCs). Upon activation by tumor-derived signals, MDSCs inhibit the ability of the host to mount an anti-tumor immune response via their capacity to suppress both the innate and adaptive immune systems. Despite their relatively recent discovery and characterization, anti-MDSC agents have been identified, which may improve immunotherapy efficacy.

Waldron, Todd J.; Quatromoni, Jon G.; Karakasheva, Tatiana A.; Singhal, Sunil; Rustgi, Anil K.

2013-01-01

61

Drawing Updates From Derivations  

Microsoft Academic Search

We propose a method for satisfying update requests in deductive databases. The setting is a generalization of the view update problem in relational databases. Updates can be drawn from goals and input clauses in derivations that are rooted at the request. An update may be invalidated by negation or integrity constraints. Thus, it may be necessary to try other updates,

Hendrik Decker; Siemens ZFE

1990-01-01

62

Functional Derivatives of Polyisobutene  

Microsoft Academic Search

The methods of synthesis of isobutene polymers with end groups of different types are examined. It is shown that advances in the synthesis of these compounds are associated with the progress in the field of the regulation of the cationic polymerisation and copolymerisation of isobutene and the degradation of isobutene polymers and copolymers. Examples of the employment of functional derivatives

Yu A. Sangalov; Yu B. Yasman

1985-01-01

63

Liquid crystalline cellulose derivatives  

SciTech Connect

Following the observation that (hydroxypropyl)cellulose in water forms an ordered cholesteric liquid crystalline phase at high polymer concentrations, reports that many other cellulose derivatives in a wide variety of solvents also form liquid crystalline solutions have appeared in the scientific and patent literature. A tabulation of cellulose-based liquid crystalline systems is presented. The formation of the ordered phase is attributed to the limited flexibility of the cellulose chain. However, some cellulose derivatives form liquid crystalline phases only in specific solvents; concentrated solutions in other solvents remain isotropic. Other cellulose derivatives, such as (hydroxypropyl)cellulose, appear to form liquid crystalline solutions in any solvent that dissolves sufficiently high concentrations of the polymer. It has been suggested that the role of flexible side-chain substituents is to allow the main chains to achieve their equilibrium orientational order. The presence of many large substituents on the cellulose backbone also increases the effective chain radius and may change the chain conformation. The effect of side-chain structure on the properties of cellulose liquid crystalline phases is thus of interest. A series of esters of (hydroxypropyl)cellulose have been prepared. In addition to forming liquid crystalline solutions in organic solvents, these materials also were found to form cholesteric thermotropic phases in the absence of solvent. The thermotropic phases show spontaneous molecular orientation and cholesteric reflection. On heating, a transformation to the isotropic melt occurs. The liquid crystalline state of cellulose and its derivatives is thus widely observed. 42 references, 4 figures, 3 tables.

Gray, D.G.

1983-01-01

64

Metal derivatives of tetrazoles  

NASA Astrophysics Data System (ADS)

Published data on the synthesis, structure, properties and applications of metal derivatives of tetrazoles are generalised and described systematically. Compounds based on the anionic and neutral tetrazole forms, C- and N-mono- and C,N-disubstituted tetrazoles are considered.

Gaponik, Pavel N.; Voitekhovich, Sergei V.; Ivashkevich, Oleg A.

2006-06-01

65

Amphetamine derivative related deaths  

Microsoft Academic Search

Amphetamine its methylendioxy (methylendioxyamphetamine methylenedioxymethylamphetamine, methylenedioxyethylamphetamine) and methoxy derivatives (p-methoxyamphetamine and p-methoxymethylamphetamine) are widely abused in Spanish society. We present here the results of a systematic study of all cases of deaths brought to the attention of the Madrid department of the Instituto Nacional de Toxicologia from 1993 to 1995 in which some of these drugs have been found in

C Lora-Tamayo; T Tena; A Rodr??guez

1997-01-01

66

Synthesis of pseudouridine derivatives  

Microsoft Academic Search

There are over one hundred modified nucleosides found in natural RNAs. Among them, pseudouridine is the most common type of modification found abundantly in RNA. Derivatives such as 1-methylpseudouridine, 3-methyl pseudouridine, and 1-methyl-3-(3-amino-3-carboxypropyl)pseudouridine are also found in nature. The overall structural and functional effects of these modified nucleosides remain unclear. Therefore, the study of these modifications is very important. The

Wantanee Sittiwong

2008-01-01

67

Functional Derivatives of Polyisobutene  

NASA Astrophysics Data System (ADS)

The methods of synthesis of isobutene polymers with end groups of different types are examined. It is shown that advances in the synthesis of these compounds are associated with the progress in the field of the regulation of the cationic polymerisation and copolymerisation of isobutene and the degradation of isobutene polymers and copolymers. Examples of the employment of functional derivatives of isobutene polymers in various branches of technology are presented. The bibliography includes 102 references.

Sangalov, Yu A.; Yasman, Yu B.

1985-07-01

68

Biomolecule derived nanostructured arrays  

Microsoft Academic Search

During the last decade, intensive research have been reported on biomimetic approaches towards achieving mono-dispersed nanoparticles, and building self-assembled system out of those (organizing nanoparticles). However the development of this research avenue is being hindered by the limited knowledge and very few practical, efficient, cost-effective approaches for implementation of the bio-derived arrays into engineering practice. The objective of this work

Zhen Yuan

2007-01-01

69

Reflexivity in derived categories  

Microsoft Academic Search

An adjoint pair of contravariant functors between abelian categories can be\\u000aextended to the adjoint pair of their derived functors in the associated\\u000aderived categories. We describe the reflexive complexes and interpret the\\u000aachieved results in terms of objects of the initial abelian categories. In\\u000aparticular we prove that, for functors of any finite cohomological dimension,\\u000athe objects of the

Francesca Mantese; Alberto Tonolo

2010-01-01

70

Computation of Mie derivatives.  

PubMed

Analytical expressions are obtained for the derivatives of Mie scattering coefficients with respect to the electrical radius of the spherical scattering particle, and to the relative permittivity and permeability of both the particle and the surrounding medium. Their corresponding approximate expressions are developed to avoid numerical overflow based on the logarithmic derivative of Riccati-Bessel functions. The analytical expressions have been verified by comparing their results with those calculated by analytical expressions developed by Mathematica. Compared with the numerical derivative, the analytical expressions and approximate expressions show a higher accuracy and are 2.0 and 2.8 times, respectively, faster in the case of a single magnetodielectric sphere. Generally, for spheres with an electrical radius in a large range, the approximate expressions can yield acceptable accuracy and computation time up to a high order. This work can be used in the design of nonmetallic metamaterials, and in the retrieval of aerosol properties from remote sensing data. An example calculation is given for the design of an optical, all-dielectric, mu-negative metamaterial consisting of a simple cubic array of tellurium nanoparticles. PMID:23852216

Li, Yang; Bowler, Nicola

2013-07-10

71

Space Derived Air Monitor  

NASA Technical Reports Server (NTRS)

COPAMS, Commonwealth of Pennsylvania Air Monitoring System, derives from technology involved in building unmanned spacecraft. The Nimbus spacecraft carried experimental sensors to measure temperature, pressure, ozone, and water vapor, and instruments for studying solar radiation and telemetry. The process which relayed these findings to Earth formed the basis for COPAMS. The COPAMS system consists of data acquisition units which measure and record pollution level, and sense wind speed and direction, etc. The findings are relayed to a central station where the information is computerized. The system is automatic and supplemented by PAQSS, PA Air Quality Surveillance System.

1983-01-01

72

Deriving Darcy's Law  

NSDL National Science Digital Library

This exercise begins with a demonstration of fluid flow through porous sediment using a constant head permeameter, with the students conducting the experiment and collecting the data. The demo is followed by a Think-Pair-Share exercise in which the question is posed to the class: "What could we change in order to increase flow through the system?" The class then works through their brainstormed list of ideas, discussing each and evaluating whether it is correct or a misconception. The students derive Darcy's Law qualitatively, based upon the results of the Think-Pair-Share exercise and discussions.

Salvage, Karen

73

Fungicide pyrazole carboxamides derivates  

US Patent & Trademark Office Database

The present invention relates to pyrazole carboxamides derivatives of formula (1) wherein Y represents CR.sup.5 or N, T represents S or O, X1 and X2 represent a chlorine or a fluorine atom, and Z1 represents a substituted or non-substituted cyclopropyl; Their process of preparation, their use as fungicide, and/or anti-mycotoxin active agents, and/or insecticide, and/or nematicide, particularly in the form of fungicide compositions, and methods for the control of phytopathogenic fungi, notably of plants, using these compounds or compositions. ##STR00001##

2014-07-08

74

Sulphenamides and their derivatives  

NASA Astrophysics Data System (ADS)

Information has been presented systematically on the synthesis of sulphenamides and related compounds by reaction of sulphenyl chlorides and sulphur chlorides with amines and carboxylic acid amides; by reaction of chloramines with mercaptans; by transamination of N-acylsulphenamides; and by reaction of disulphides with amines. The following chemical reactions of sulphenamides have been examined: reaction with hydrogen halides; with acids and derivatives possessing coordinatively unsaturated atoms; and the addition of sulphenamides to the double bond of carbon disulphide, isocyanates, isothiocyanates and olefins. Data are given on the physical state of sulphenamides and on the region characteristic of the S-N bond vibrations. The bibliography includes 190 references.

Petrov, K. A.; Rudnev, G. V.; Sorokin, V. D.

1990-09-01

75

Connective tissue derived polypeptides  

US Patent & Trademark Office Database

The present invention relates to compositions comprising one or more connective tissue derived polypeptides having a molecular weight of less than 30,000 Da that are capable of tolerising individuals to antigenic components of cartilage and prevent the appearance of and/or treat symptoms of arthritis and other musculoskeletal degenerative conditions. The present invention provides methods for recovering polypeptides having a molecular weight of less than 30,000 Da from connective tissue and having anti-arthritic or anti-inflammatory activity. The present invention further relates to compositions comprising a polypeptide containing an NC4 domain of collagen type IX alpha 1 chain or fragment thereof, having a molecular weight of less than 30,000 Da, where the polypeptide is capable of tolerising individuals to antigenic components of cartilage, preventing the appearance of arthritic symptoms, and/or treating the symptoms of arthritis.

2011-04-05

76

Derivation of model topography  

NASA Technical Reports Server (NTRS)

The Fourth-Order model necessitates representation of the topography. The problem of the representation of the topography at grid points is addressed. The attempted was to derive an envelope topography. The TI is obtained by taking local mean plus one standard deviation at each grid point and sigma filtering it. The method was greatly influenced by large standard deviations at steep mountains. The O1 topography is the local mean. The S1 is obtained by Sigma filtering in both latitude and longitude the mean O1. The S2 is when the operation is applied twice and S3 thrice, the Q3 is the sigma filtered local mean of the upper third quantile of the source data.

Balgovind, R. C.

1985-01-01

77

Inositol derivatives: evolution and functions  

Microsoft Academic Search

Current research on inositols mainly focuses on myo-inositol (Ins) derivatives in eukaryotic cells, and in particular on the many roles of Ins phospholipids and polyphosphorylated Ins derivatives. However, inositols and their derivatives are more versatile than this — they have acquired diverse functions over the course of evolution. Given the central involvement of primordial bacteria and archaea in the emergence

Robert H. Michell

2008-01-01

78

DRS: Derivational Reasoning System  

NASA Technical Reports Server (NTRS)

The high reliability requirements for airborne systems requires fault-tolerant architectures to address failures in the presence of physical faults, and the elimination of design flaws during the specification and validation phase of the design cycle. Although much progress has been made in developing methods to address physical faults, design flaws remain a serious problem. Formal methods provides a mathematical basis for removing design flaws from digital systems. DRS (Derivational Reasoning System) is a formal design tool based on advanced research in mathematical modeling and formal synthesis. The system implements a basic design algebra for synthesizing digital circuit descriptions from high level functional specifications. DRS incorporates an executable specification language, a set of correctness preserving transformations, verification interface, and a logic synthesis interface, making it a powerful tool for realizing hardware from abstract specifications. DRS integrates recent advances in transformational reasoning, automated theorem proving and high-level CAD synthesis systems in order to provide enhanced reliability in designs with reduced time and cost.

Bose, Bhaskar

1995-01-01

79

Synthesis of some pyridone derivatives.  

PubMed

Chlorination of 6-aryl-3-cyano-2-pyridone-4-carboxylic acid (1) afforded the corresponding acid chloride (2) and the 2-chloro derivative (3). Esterification of (2) gave the corresponding esters (4a; b). Hydrazinolysis of (4a) afforded the respective pyridazinone derivative (5). Treatment of 6-aryl-2-chloro-3-cyano-4-pyridine carboxylic acid (3) with acetyl hydrazine, gave the triazinopyridine derivative (6), while treatment of 3 with sodium azide in DMF afforded the tetrazinopyridine derivative (7). Treatment of the N-acetyl derivative (1b) with thiosemicarbazide and/or hydroxylamine hydrochloride, yielded the correspoding semicarbazone and oxine derivatives (8) and (10), respectively. The reaction of 6-aryl-3-cyano-1,2-dihydro-2-thioxo-4-pyridinecarboxylic acid (1c) with ethylchloro acetate and/or thiourea yielded the mercapto ester derivative (11) and the corresponding pyrido [2,3-d] pyrimidine thione derivative (12). Condensation reaction of (1d) with anthranilic acid, afforded the quinazolone derivative (11). The reactivity of 11 towards hydrazine hydrate was investigated. The structural assignment of the new derivatives were based on IR, 1H NMR and mass data. Some of the new compounds were screened, in vitro, for antimicrobial activity and the results were encouraging. PMID:11486604

Dawood, N T; Abdel-Gawad, S M; Soliman, F M

2001-01-01

80

Effects of Alkyl Substitution on the Physical Properties and Gas Transport Behavior in Selected Poly(R-phenoxyphosphazenes)  

SciTech Connect

A systematic preparation of alkyl substituted phenoxy-phosphazene polymers was performed. In this study, phosphazenes substituted with 4-methylphenol, 4-ethylphenol, and 4-isopropylphenol are reported. An additional polymer substituted with 4-tert-butylphenoxy-1-ethanol also was synthesized in this work. Data derived for these materials, including chemical, thermal and gas transport characterization, were compared to previous reports discussing poly[bis-phenoxyphosphazene] and its analog with tert-butyl substitution: poly[bis-(4-tert-butylphenoxy)phosphazene]. The tert-butyl moiety influences orderly chain packing, presumably through steric hindrance that can influence aromatic p-stacking. For the new poly[(alkylphenoxy)phosphazenes], semi-crystallinity is maintained and the added steric bulk serves to decrease the Tg and increase both permeability and selectivity for the gas pairs: O2/N2 and CO2/CH4. Removal of the tert-butyl moiety from the immediate vicinity of the backbone through a flexible spacer serves to depress the Tg as compared to poly[bis-(4-tert-butylphenoxy)phosphazene], but provides no performance enhancement for gas transport.

Mark D. Ogden; Christopher J. Orme; Frederick F. Stewart

2011-08-01

81

Tetrahydropentalenyl-phosphazene constrained geometry complexes of rare-earth metal alkyls.  

PubMed

Reactions of Cp™HPPh2 (1, diphenyl(4,4,6,6-tetramethyl-1,4,5,6-tetrahydropentalen-2-yl)phosphane) with the organic azides AdN3 and DipN3 (Ad = 1-adamantyl; Dip = 2,6-di-iso-propylphenyl) led to the formation of two novel CpPN ligands: P-amino-cyclopentadienylidene-phosphorane (Cp™PPh2NHAd; L(Ad)H) and P-cyclopentadienyl-iminophosphorane (Cp™HPPh2NDip; L(Dip)H). Both were characterized by NMR spectroscopy and X-ray structure analysis. For both compounds only one isomer was observed. Neither possesses any detectable prototropic or elementotropic isomers. Reactions of these ligands with [Lu(CH2SiMe3)3(thf)2] or with rare-earth metal halides and three equivalents of LiCH2SiMe3 produced the desired bis(alkyl) Cp™PN complexes: [{Cp™PN}M(CH2SiMe3)2] (M = Sc (1(Ad), 1(Dip)), Lu (2(Ad), 2(Dip)), Y (3(Ad), 3(Dip)), Sm (4(Ad)), Nd (5(Ad)), Pr (6(Ad)), Yb (7(Ad))). These complexes were characterized by extensive NMR studies for the diamagnetic and the paramagnetic complexes with full signal assignment. An almost mirror inverted order of the paramagnetic shifts has been observed for ytterbium complex 7(Ad) compared to 4(Ad), 5(Ad) and 6(Ad). For the assignment of the NMR signals [{?(1)?:??(5)-C5Me4PMe2NAd}Yb(CH2SiMe3)2] 7 was synthesized, characterized and the (1)H NMR signals were compared to 7(Ad) and to other paramagnetic lanthanide complexes with the same ligand. 1(Ad), 2(Ad), 2(Dip), 3(Ad) and 3(Dip) were characterized by X-ray structure analysis revealing a sterically congested constrained geometry structure. PMID:24671310

Hangaly, Noa K; Petrov, Alexander R; Elfferding, Michael; Harms, Klaus; Sundermeyer, Jörg

2014-05-21

82

Liquid Crystalline Phosphazenes. High Polymeric and Cyclic Trimmeric Systems with Aromatic Azo Side Groups.  

National Technical Information Service (NTIS)

Liquid crystalline polymers are an important subject for fundamental and technological studies because of their unusual anisotropid optical, electrical, and mechanical properties. Liquid crystalline polymers fall into two general categories: 1) species wi...

H. R. Allock C. Kim

1989-01-01

83

Phosphazene Based Additives for Improvement of Safety and Battery Lifetimes in Lithium-Ion Batteries  

Microsoft Academic Search

There need to be significant improvements made in lithium-ion battery technology, principally in the areas of safety and useful lifetimes to truly enable widespread adoption of large format batteries for the electrification of the light transportation fleet. In order to effect the transition to lithium ion technology in a timely fashion, one promising next step is through improvements to the

Mason K Harrup; Kevin L Gering; Harry W Rollins; Sergiy V Sazhin; Michael T Benson; David K Jamison; Christopher J Michelbacher

2011-01-01

84

Biomolecule derived nanostructured arrays  

NASA Astrophysics Data System (ADS)

During the last decade, intensive research have been reported on biomimetic approaches towards achieving mono-dispersed nanoparticles, and building self-assembled system out of those (organizing nanoparticles). However the development of this research avenue is being hindered by the limited knowledge and very few practical, efficient, cost-effective approaches for implementation of the bio-derived arrays into engineering practice. The objective of this work is to biomimeticaly form nanocomposite materials using a simple, rapid, inexpensive, scalable approach, which is general enough and not limited to colloidal particle self-assembly. Throughout the studies, we have developed a universally applicable process, which is to fabricate macro-biomolecular arrays on solid substrates based on the convective self-assembly of colloidal particles. We have demonstrated that protein (ferritin) and virus (phage) arrays were directly deposited onto solid substrates such as glass, silicon wafer, and gold substrate in closed or near closed-packed order. The arrays were further incorporated into a more robust silica matrix, in such that strengthens the thermal stability and provides porous accessibility. After treatment in controlled pyrolysis, the organic protein shell was removed, left mono-dispersed iron-oxide nanoparticles intact on the substrate or in the silica matrix. Both iron-oxide nanoparticles arrays with or without silica matrix have been further characterized to possess superferromagnetic properties at low temperature (15 K), same as that in bulk material. Initial work on protein patterning, through combining either lithography based top-down or bottom-up techniques with our novel deposition approach, was presented as well. Thin film deposition of mesoporous materials using convective self-assembly is another main part in this work. Both silica and carbon mesoporous thin films were successfully formed using the convective self-assembly horizontal-coating approach. We have shown that ultra thin mesoporous film (less than 100 nm) could be obtained through increasing the coating speed with the solution concentration remained same. Combining with lithographically patterned surface, the mesoporous thin films will be well suited for applications for bio-sensing, separations and etc. Studies were also carried out on the transport of fluid and electric current in fluidic channels with size in nanometer range; particular attention was paid on the effect of the electrolyte valence. At these dimensions new physical phenomena begin to occur because the electric double layers formed at the channel walls become comparable to the channel width and the overall wall surface to channel volume ratio increases. Numerical analysis predicts that the electrokinetic transport phenomena differ from multivalent ions to monovalent ions in the nanochannel when double layer overlap is large. This dependence affects the transport of current, fluid and dissolved analytes in a fluidic channel. The valence of the dissolved counterions determines the electric current and fluid flow in a nanochannel by shaping the electrostatic potential distribution. Our calculation shows that in absence of strong adsorption at the wall, divalent counterions lead to greater current and fluid flow than monovalent electrolyte for the same overall ionic strength. The results also indicate that control over the transport processes in fluidic nanochannels can be accomplished through properly selecting and combining electrolytes.

Yuan, Zhen

85

Optimal hedging of variance derivatives  

Microsoft Academic Search

We examine the optimal hedging of derivatives written on realised variance, focussing principally on variance swaps (VS) (but, en route, also considering skewness swaps), when the underlying stock price has discontinuous sample paths, i.e. jumps. In general, with jumps in the underlying, the market is incomplete and perfect hedging is not possible. We derive easily implementable formulae which give optimal

John Crosby

2012-01-01

86

Elementary derivation of Kepler's laws  

Microsoft Academic Search

A simple derivation of all three so-called Kepler laws is presented in which the orbits, bound and unbound, follow directly and immediately from conservation of energy and angular momentum. The intent is to make this crowning achievement of Newtonian mechanics easily accessible to students in introductory physics courses. The method is also extended to simplify the derivation of the Rutherford

Erich Vogt

1996-01-01

87

Derivatives Markets for Home Prices  

Microsoft Academic Search

The establishment recently of risk management vehicles for home prices is described. The potential value of such vehicles, once they become established, is seen in consideration of the inefficiency of the market for single family homes. Institutional changes that might derive from the establishment of these new markets are described. An important reason for these beginnings of real estate derivative

Robert J. Shiller

2008-01-01

88

2-(4-Methyl-pyridin-2-yl)-4?,4?,6?,6?-tetra-kis-(pyrrolidin-1-yl)-1H,2H-spiro-[naphtho-[1,2-e][1,3,2]oxaza-phosphinine-3,2?-[1,3,5,2,4,6]tri-aza-triphosphinine  

PubMed Central

In the title spiro-phosphazene derivative, C33H46N9OP3, the phosphazene and six-membered N/O rings are in flattened chair and twisted-boat conformations, respectively. The naphthalene ring system and the pyridine ring are oriented at a dihedral angle of 41.82?(4)°. In the crystal, weak C—H?O hydrogen bonds link the mol­ecules related by translation along the a axis into chains. C—H?? inter­actions aggregate these chains into layers parallel to the ab plane.

Is?klan, Muhammet; Sonkaya, Omer; Hokelek, Tuncer

2013-01-01

89

Organoelementary Derivatives of Barenes (Carboranes-10)  

Microsoft Academic Search

CONTENTS I. Introduction 173 II. Magnesium and alkali-metal derivatives; syntheses based on them 174 III. Barenyl derivatives of boron 177 IV. Derivatives of Group IV elements 178 V. Derivatives of Group V elements (phosphorus, arsenic, antimony) 179 VI. Mercury derivatives 180 VII. Organometallic derivatives of dicarbaundecaborane 182 Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find

Vladimir I. Bregadze; O. Yu Okhlobystin

1968-01-01

90

Quinazoline derivatives: synthesis and bioactivities.  

PubMed

Owing to the significant biological activities, quinazoline derivatives have drawn more and more attention in the synthesis and bioactivities research. This review summarizes the recent advances in the synthesis and biological activities investigations of quinazoline derivatives. According to the main method the authors adopted in their research design, those synthetic methods were divided into five main classifications, including Aza-reaction, Microwave-assisted reaction, Metal-mediated reaction, Ultrasound-promoted reaction and Phase-transfer catalysis reaction. The biological activities of the synthesized quinazoline derivatives also are discussed. PMID:23731671

Wang, Dan; Gao, Feng

2013-01-01

91

Complex higher order derivative theories  

SciTech Connect

In this work is considered a complex scalar field theory with higher order derivative terms and interactions. A procedure is developed to quantize consistently this system avoiding the presence of negative norm states. In order to achieve this goal the original real scalar high order field theory is extended to a complex space attaching a complex total derivative to the theory. Next, by imposing reality conditions the complex theory is mapped to a pair of interacting real scalar field theories without the presence of higher derivative terms.

Margalli, Carlos A.; Vergara, J. David [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, Mexico 04510 DF (Mexico)

2012-08-24

92

MCR Synthesis of Praziquantel Derivatives  

PubMed Central

Schistosomiasis, a high volume neglected tropical disease affecting more than 200 million people worldwide, can only be effectively treated by the tetrahydroisoquinoline drug praziquantel (PZQ). Herein, we describe an efficient approach to access PZQ derivatives by the Ugi 4-component reaction followed by the Pictet-Spengler reaction in a two-step, one-pot procedure. 30 Novel PZQ derivatives are described based on the Ugi 4-component reaction and an X-ray structure of a novel derivative revealing different conformation compared with PZQ is discussed. Several analogues comparable in activity to the drug PZQ have been identified based on an in vitro Schistosoma mansoni worm viability assay.

Liu, Haixia; William, Samia; Herdtweck, Eberhardt; Botros, Sanaa; Domling, Alexander

2013-01-01

93

Elevation Derivatives for National Applications  

USGS Publications Warehouse

The Elevation Derivatives for National Applications (EDNA) project is a multi-agency effort to develop standard topographically derived layers for use in hydrologic and environmental modeling. The EDNA takes advantage of the seamless and filtered characteristics for the National Elevation Dataset (NED) to create a hydrologically conditioned Digital Elevation Model (DEM) useful for modeling applications. The goals of the project are to create a hydrologically conditioned DEM and systematically extract a set of standard derivatives that can be used to facilitate data integration with other U.S. Geological Survey (USGS) framework data sets such as the National Hydrography Dataset (NHD) and the Watershed Boundaries Dataset (WBD).

Geological Survey (U.S.)

2005-01-01

94

Quinazoline derivatives: synthesis and bioactivities  

PubMed Central

Owing to the significant biological activities, quinazoline derivatives have drawn more and more attention in the synthesis and bioactivities research. This review summarizes the recent advances in the synthesis and biological activities investigations of quinazoline derivatives. According to the main method the authors adopted in their research design, those synthetic methods were divided into five main classifications, including Aza-reaction, Microwave-assisted reaction, Metal-mediated reaction, Ultrasound-promoted reaction and Phase-transfer catalysis reaction. The biological activities of the synthesized quinazoline derivatives also are discussed.

2013-01-01

95

Biologically-Active Xanthine Derivatives.  

National Technical Information Service (NTIS)

Certain functionalized congeners of 1,3-dialkylxanthine exhibit high potency and selectivity as antagonists for A1- and A2-adenosine receptors and are suitable for attachment to probes, drug carriers, or solid supports. These derivatives are characterized...

K. A. Jacobson J. W. Daly K. L. Kirk

1984-01-01

96

Alkylsilyl derivatives for gas chromatography.  

PubMed

Alkylsilyl reagents are the most widely used reagents for the derivatization of polar compounds containing labile hydrogen atoms for gas chromatography. In this article the reagents and reaction conditions for the formation of trimethylsilyl, alkyldimethylsilyl (particularly t-butyldimethylsilyl), cyclic siliconides, haloalkyldimethylsilyl, and flophemesyl (pentafluorophenyldimethylsilyl) derivatives for a wide range of functional groups are reviewed. The importance of steric hindrance on reaction rates and completion, choice of reaction conditions, stability of derivatives, and options for selective detection are described. PMID:23465130

Poole, Colin F

2013-06-28

97

Nucleoside derivatives from the marine-derived fungus Aspergillusversicolor.  

PubMed

Four nucleoside derivatives (1-4) were isolated from the fungus Aspergillus versicolor derived from the gorgonian Dichotella gemmacea collected in the South China Sea. Their structures were elucidated by comprehensive spectroscopic method of NMR and MS analysis. All isolated metabolites were evaluated for their cytotoxicity, antibacterial activity and lethality towards brine shrimp Artemia salina. Compounds 1/2 exhibited selective antibacterial activity against Staphylococcus epidermidis with an MIC value of 12.5 ?M. It should be noted that 1 and 2, whose structures were listed in SciFinder Scholar, had no associated reference. This is the first report about their isolation, structure elucidation and biological activities. PMID:24670197

Chen, Min; Fu, Xiu-Mei; Kong, Chui-Jian; Wang, Chang-Yun

2014-01-01

98

Fractional Derivatives in Dengue Epidemics  

NASA Astrophysics Data System (ADS)

We introduce the use of fractional calculus, i.e., the use of integrals and derivatives of non-integer (arbitrary) order, in epidemiology. The proposed approach is illustrated with an outbreak of dengue disease, which is motivated by the first dengue epidemic ever recorded in the Cape Verde islands off the coast of west Africa, in 2009. Numerical simulations show that in some cases the fractional models fit better the reality when compared with the standard differential models. The classical results are obtained as particular cases by considering the order of the derivatives to take an integer value.

Pooseh, Shakoor; Rodrigues, Helena Sofia; Torres, Delfim F. M.

2011-09-01

99

Magnetic cellulose-derivative structures  

DOEpatents

Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorption agents can be incorporated during the manufacture of the structure. 3 figs.

Walsh, M.A.; Morris, R.S.

1986-09-16

100

Empirically derived injury prevention rules.  

PubMed Central

This study describes a set of empirically derived safety rules that if followed, would have prevented the occurrence of minor injuries. Epidemiologists have criticized behavioral interventions as increasing "safe" behavior but failing to demonstrate a decrease in injury. The present study documents retrospectively the link between safe behavior and injury. It demonstrates that these empirically derived rules are very similar to rules for the prevention of serious injury. The study also shows that these rules are not widely accepted and implemented by parents. Suggestions for future research in this area are advanced.

Peterson, L; Schick, B

1993-01-01

101

Magnetic cellulose-derivative structures  

DOEpatents

Structures to serve as selective magnetic sorbents are formed by dissolving a cellulose derivative such as cellulose triacetate in a solvent containing magnetic particles. The resulting solution is sprayed as a fine mist into a chamber containing a liquid coagulant such as n-hexane in which the cellulose derivative is insoluble but in which the coagulant is soluble or miscible. On contact with the coagulant, the mist forms free-flowing porous magnetic microspheric structures. These structures act as containers for the ion-selective or organic-selective sorption agent of choice. Some sorbtion agents can be incorporated during the manufacture of the structure.

Walsh, Myles A. (Falmouth, MA); Morris, Robert S. (Fairhaven, MA)

1986-09-16

102

40 CFR 721.1820 - Bisphenol derivative.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Bisphenol derivative. 721.1820 Section 721...Chemical Substances § 721.1820 Bisphenol derivative. (a) Chemical substance...chemical substance identified generically as bisphenol derivative (PMN No....

2009-07-01

103

40 CFR 721.1820 - Bisphenol derivative.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Bisphenol derivative. 721.1820 Section 721...Chemical Substances § 721.1820 Bisphenol derivative. (a) Chemical substance...chemical substance identified generically as bisphenol derivative (PMN No....

2013-07-01

104

On the Higher Derivatives of Bellman'S Equation.  

National Technical Information Service (NTIS)

Bellman's equation is analysed by taking derivatives of all orders. It is found that unlike the second derivative which satisfies a nonlinear equation, the third and higher derivatives of the optimal value function satisfy linear differential equations al...

S. B. Gershwin

1969-01-01

105

Insider Trading in Credit Derivatives  

Microsoft Academic Search

Insider trading in the credit derivatives market has become a significant concern for regulators and participants. This paper attempts to quantify the problem. Using news reflected in the stock market as a benchmark for public information, we report evidence of significant incremental information revelation in the credit default swap (CDS) market, consistent with the occurrence of insider trading. We show

Viral V Acharya; Tim Johnson

2005-01-01

106

Microalgae derived biofuels and processes  

Microsoft Academic Search

only renewable biodiesel that can potentially completely displace liquid fuels derived from petroleum. The energy conversion reaction of microalgae can be classified into biochemical, thermochemical. Biochemical conversion can be further subdivided into alcoholic fermentation, anaerobic digestion and photobiological hydrogen production. Thermochemical conversion can be subdivided into gasification, pyrolysis and liquefaction. The productions of these processes include ethanol, methane, H2, Syngas,

Yibin Tian; Chunhu Li; Junjie Bian; Lijuan Feng

2011-01-01

107

Informational derivation of quantum theory  

SciTech Connect

We derive quantum theory from purely informational principles. Five elementary axioms - causality, perfect distinguishability, ideal compression, local distinguishability, and pure conditioning - define a broad class of theories of information processing that can be regarded as standard. One postulate - purification - singles out quantum theory within this class.

Chiribella, Giulio; D'Ariano, Giacomo Mauro; Perinotti, Paolo [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Ontario, N2L 2Y5 (Canada); QUIT Group, Dipartimento di Fisica ''A. Volta'' and INFN Sezione di Pavia, via Bassi 6, I-27100 Pavia (Italy)

2011-07-15

108

Type-2 fuzzy fractional derivatives  

NASA Astrophysics Data System (ADS)

In this paper, we introduce two definitions of the differentiability of type-2 fuzzy number-valued functions of fractional order. The definitions are in the sense of Riemann-Liouville and Caputo derivative of order ? ? (0, 1), and based on type-2 Hukuhara difference and H2-differentiability. The existence and uniqueness of the solutions of type-2 fuzzy fractional differential equations (T2FFDEs) under Caputo type-2 fuzzy fractional derivative and the definition of Laplace transform of type-2 fuzzy number-valued functions are also given. Moreover, the approximate solution to T2FFDE by a Predictor-Evaluate-Corrector-Evaluate (PECE) method is presented. Finally, the approximate solutions of two examples of linear and nonlinear T2FFDEs are obtained using the PECE method, and some cases of T2FFDEs applications in some sciences are presented.

Mazandarani, Mehran; Najariyan, Marzieh

2014-07-01

109

Guggullipid derivatives: synthesis and applications.  

PubMed

Two guggullipid derivatives, Z-guggulsulfate [4,17(20)-pregnadiene-3-one-16beta-sulfate] sodium salt and Z-guggullaurate [4,17(20)-pregnadiene-3-one-16beta-laurate], have been synthesized and evaluated for liposomal drug delivery system. Its precursor, Z-guggulsterol [4,17(20)-pregnadiene-3-one-16beta-ol], is also synthesized in gram scale starting from guggulsterone using the novel combination of known reactions in fewer steps and with higher yield than previously reported synthesis. These new synthetic guggullipid derivatives were also used in the preparation of liposomes. This new class of lipid molecules will be a useful tool in the development of nanosomal or liposomal drug delivery system. PMID:20188717

Ahmad, Moghis U; Ali, Shoukath M; Ahmad, Ateeq; Sheikh, Saifuddin; Ahmad, Imran

2010-05-01

110

Stilbene derivatives from Gnetum cleistostachyum.  

PubMed

Three new stilbene derivatives, named gnetucleistol A (1), B (2) and C (3), together with four known compounds, gnetifolin A (4), p-hydroxycinnamic acid (5), piceatannol (6) and resveratrol (7), were isolated from Gnetum cleistostachyum C.Y. Cheng (Gnetaceae). Their structures were elucidated on the basis of spectroscopic evidence (EI-MS, UV, IR, NOE, 1H, 13C and 2D NMR). PMID:15621615

Yao, Chun-Suo; Lin, Mao; Liu, Xin; Wang, Ying-Hong

2005-04-01

111

Reid's recipe and derived categories  

Microsoft Academic Search

We prove two conjectures from Cautis and Logvinenko (2009) [CL09] which describe the geometrical McKay correspondence for a finite, abelian subgroup of SL3(C). We do it by studying the relation between the derived category mechanics of computing a certain Fourier–Mukai transform and a piece of toric combinatorics known as ‘Reid's recipe’, effectively providing a categorification of the latter.

Timothy Logvinenko

2010-01-01

112

Binder enhanced refuse derived fuel  

DOEpatents

A refuse derived fuel (RDF) pellet having about 11% or more particulate calcium hydroxide which is utilized in a combustionable mixture. The pellets are used in a particulate fuel bring a mixture of 10% or more, on a heat equivalent basis, of the RDF pellet which contains calcium hydroxide as a binder, with 50% or more, on a heat equivalent basis, of a sulphur containing coal. Combustion of the mixture is effective to produce an effluent gas from the combustion zone having a reduced SO.sub.2 and polycyclic aromatic hydrocarbon content of effluent gas from similar combustion materials not containing the calcium hydroxide.

Daugherty, Kenneth E. (Lewisville, TX) [Lewisville, TX; Venables, Barney J. (Denton, TX) [Denton, TX; Ohlsson, Oscar O. (Naperville, IL) [Naperville, IL

1996-01-01

113

Iron and iron derived radicals  

SciTech Connect

We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fastexclamation Think smallexclamation In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab.

Borg, D.C.; Schaich, K.M.

1987-04-01

114

Myeloid-derived suppressor cells  

PubMed Central

While conventional anticancer therapies, including surgical resection, radiotherapy, and/or chemotherapy, are relatively efficient at eliminating primary tumors, these treatment modalities are largely ineffective against metastases. At least in part, this reflects the rather inefficient delivery of conventional anticancer agents to metastatic lesions. We have recently demonstrated that myeloid-derived suppressor cells (MDSCs) can be used as cellular missiles to selectively deliver a radioisotope-coupled attenuated variant of Listeria monocytogenes to both primary and metastatic neoplastic lesions in mice with pancreatic cancer. This novel immunotherapeutic intervention robustly inhibited tumor growth while promoting a dramatic decrease in the number of metastases.

Chandra, Dinesh; Gravekamp, Claudia

2013-01-01

115

Shuttle derived unmanned launch vehicle  

NASA Astrophysics Data System (ADS)

An unmanned launch vehicle derived using existing Space Transportation System (STS) components was studied. The vehicle incorporates a standard STS external tank and solid rocket boosters, a new payload module and a recoverable propulsion/avionics module housing the high cost avionics and propulsion systems. The main propulsion system is a cluster of three STS space shuttle main engines compatible with the STS launch pad. The orbital maneuvering system utilizes components and the reaction control system incorporates modified STS primary and vernier thrusters. A solid rocket propulsion system made up of six motors having a two second burn time is incorporated for decelerating the recoverable propulsion/avionics module to a soft landing. The sidemount shuttle derived launch vehicle can carry 147,000 pounds to a 150 nautical mile circular orbit from the Eastern Test Range of 104,000 pounds from the Western Test Range. With Centaur G-prime the payload capability to geosynchronous earth orbit is 24,500 pounds. Performance with an optimized upper stage and a stretched external tank was also investigated.

Buell, D. N.; Tewell, J. R.

1985-04-01

116

40 CFR 721.10039 - Diethoxybenzenamine derivative, diazotized, coupled with aminonaphthalenesulfonic acid derivative...  

Code of Federal Regulations, 2011 CFR

...aminonaphthalenesulfonic acid derivative, ammonium salt (generic). 721.10039 Section 721...aminonaphthalenesulfonic acid derivative, ammonium salt (generic). (a) Chemical substance...aminonaphthalenesulfonic acid derivative, ammonium salt (PMN P-02-514) is subject to...

2011-07-01

117

Likelihood Ratio Derivative Estimators for Stochastic Systems.  

National Technical Information Service (NTIS)

This paper discusses the likelihood ratio derivative estimation techniques for stochastic systems. After a brief review of the basic concepts, likelihood ratio derivative estimators are presented for the following classes of stochastic processes: time hom...

P. W. Glynn

1989-01-01

118

12 CFR 403.4 - Derivative classification.  

Code of Federal Regulations, 2010 CFR

...the case of multiple source documents. (b) New Material. (1) New material that derives its classification from information...as assigned to the source information. (2) New material that derives its classification under prior...

2009-01-01

119

12 CFR 403.4 - Derivative classification.  

Code of Federal Regulations, 2010 CFR

...the case of multiple source documents. (b) New Material. (1) New material that derives its classification from information...as assigned to the source information. (2) New material that derives its classification under prior...

2010-01-01

120

Derivation of Equations for Variable Rainfall Infiltration.  

National Technical Information Service (NTIS)

Formulae were derived for prediction of ponding time and cumulative infiltration following ponding under a condition of variable and even intermittent rainfall. The derivations do not assume immediate saturation at the surface nor a piston displacement of...

H. J. Morel-Seytoux

1977-01-01

121

Derivative Sign Patterns in Two Dimensions  

ERIC Educational Resources Information Center

Given a function defined on a subset of the plane whose partial derivatives never change sign, the signs of the partial derivatives form a two-dimensional pattern. We explore what patterns are possible for various planar domains.

Schilling, Kenneth

2013-01-01

122

Evaluation of Derivatives of Gaussian Integrals.  

National Technical Information Service (NTIS)

We show that by a suitable change of variables, the derivatives of molecular integrals over Gaussian-type functions required for analytic energy derivatives can be evaluated with significantly less computational effort than current formulations. The reduc...

T. Helgaker P. R. Taylor

1992-01-01

123

Antibacterial activity of thioetherhydroxyethylsulfonamide derivatives.  

PubMed

Thioetherhydroxyethylsulfonamide derivatives were synthesized and evaluated for their in vitro antibacterial activity against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923). Results have shown that compounds 8c and 9e display potent activity (MIC = 0.125 µg/mL) against E. coli when compared with the standard drug sulfamethoxazole (SMZ, MIC < 0.5 µg/mL) for this same strain. All the new compounds were fully identified and characterized by NMR ((1)H and (13)C) and X-ray crystallography (for compound 8c). This class of compounds can be considered as a good starting point for the development of new lead molecules in the fight against multi-drug bacterial resistance. PMID:24533504

Vellasco, Walcimar T; Guedes, Guilherme P; Facchinetti, Victor; Vasconcelos, Thatyana R A; Vaz, Maria G F; Cunico, Wilson; de Souza, Marcus V N; de Paula, Geraldo R; Fleming, Maria E C K; Gomes, Claudia R B

2014-05-01

124

[Coliphages inactivation using chitosan derivatives].  

PubMed

The effect of chitosan fragments with different degrees of polymerization and the chemical derivatives of chitosan differing in the number of amino groups and total molecule charge on phages T2, T4, and T7 was studied. The interaction of chitosan with bacteriophage particles inactivated them to the extent dependent on the chemical properties of chitosan and its concentration. Phage T2 was found to be most susceptible to inactivation by chitosan. The polycationic nature of chitosan plays an important role in the inactivation of phages. It is assumed that the abnormal rearrangement of the basal plate of phages, the loss of long tail fibers, and probably, modification of the receptor-recognizing phage proteins may be responsible for the inactivation of coliphages by chitosan. PMID:10776628

Kochkina, Z M; Surgucheva, N A; Chirkov, S N

2000-01-01

125

Using derivatives to hedge against the unexpected.  

PubMed

Derivatives--financial instruments with a rate of return derived from an underlying asset--have been used as investment instruments for decades. Many derivative products originally were created explicitly for the purpose of reducing financial risks and have become more widely used and more complex in recent years. Healthcare financial managers should have a basic understanding of derivatives as well as the ability to apply general guidelines for their appropriate use in healthcare financial management. PMID:10154438

Aderholt, J M; Rasmussen, R H

1996-02-01

126

Analytic Derivatives for Linear Rational Expectations Models  

Microsoft Academic Search

This paper sets out the analytic solution for the calculation of exact derivatives in linear rational expectations models with reference to the optimal simple rule problem. We argue that there are substantial computational advantages of using analytic derivatives and compare the likely computational costs of using approximate and exact derivatives when calculating optimal coefficients for simple feedback rules. A specific

Andrew P. Blake

2004-01-01

127

Improved Second Derivative Test for Relative Extrema  

ERIC Educational Resources Information Center

In this note, a modified Second Derivative Test is introduced for the relative extrema of a single variable function. This improved test overcomes the difficulty of the second derivative vanishing at the critical point, while in contrast the traditional test fails for this case. A proof for this improved Second Derivative Test is presented,…

Wu, Yan

2007-01-01

128

Additive (?, ?) -Jordan derivations on CSL algebras  

NASA Astrophysics Data System (ADS)

Let L be an CSL algebra. Where ?, ? are surjective homomorphisms on L. We say that an additive (linear) mapping ? of L into self is called an additive (linear)(?, ?) -derivation if ?(AB)= ?(A)?(B)+?(A)?(B) for any A, B?L. In this paper we show that an additive (?, ?) -Jordan derivation on a CSL-algebra is an additive (?, ?)-derivation.

Majeed, Asia

2010-11-01

129

Structural design utilizing updated, approximate sensitivity derivatives  

NASA Technical Reports Server (NTRS)

A method to improve the computational efficiency of structural optimization algorithms is investigated. In this method, the calculations of 'exact' sensitivity derivatives of constraint functions are performed only at selected iterations during the optimization process. The sensitivity derivatives utilized within other iterations are approximate derivatives which are calculated using an inexpensive derivative update formula. Optimization results are presented for an analytic optimization problem (i.e., one having simple polynomial expressions for the objective and constraint functions) and for two structural optimization problems. The structural optimization results indicate that up to a factor of three improvement in computation time is possible when using the updated sensitivity derivatives.

Scotti, Stephen J.

1993-01-01

130

Representations of partial derivatives in thermodynamics  

NSDL National Science Digital Library

One of the mathematical objects that students become familiar with in thermodynamics, often for the first time, is the partial derivative of a multivariable function. The symbolic representation of a partial derivative and related quantities present difficulties for students in both mathematical and physical contexts, most notably what it means to keep one or more variables fixed while taking the derivative with respect to a different variable. Material properties are themselves written as partial derivatives of various state functions (e.g., compressibility is a partial derivative of volume with respect to pressure). Research in courses at the University of Maine and Oregon State University yields findings related to the many ways that partial derivatives can be represented and interpreted in thermodynamics. Research has informed curricular development that elicits many of the difficulties using different representations (e.g., geometric) and different contexts (e.g., connecting partial derivatives to specific experiments).

Thompson, John R.; Manogue, Corinne A.; Roundy, David J.; Mountcastle, Donald B.

2012-05-15

131

Efficient Derivative-Free Optimization  

NASA Astrophysics Data System (ADS)

When optimizing the parameters affecting the evolution of a chaotic system, a peculiar challenge arises. The infinite-time average of the statistic of interest is only approximated by any finite-time simulation, with the truncation errors effectively decorrelated from one simulation to the next. Thus, the optimization surface is nonsmooth, and gradient-based optimization algorithms are ill suited. One of the most efficient derivative-free optimization algorithm available for such problems is the Surrogate Management Framework (SMF), which fits an interpolating function to the available data to identify regions of interest. The SMF is based on an underlying grid structure, with all function evaluations performed on this grid. Once discrete convergence is obtained, the grid is refined and the process repeated. In all previous SMF codes, Cartesian grids have been used. However, Cartesian grids are not nearly as uniform at packing or covering parameter space as various alternatives available from n-dimensional sphere packing theory. In the present talk, we show that, by leveraging such packings, the number of function evaluations required for convergence of the SMF algorithm is substantially reduced.

Belitz, Paul; Bewley, Thomas

2007-11-01

132

Animal-derived pharmaceutical proteins.  

PubMed

Livestock animals have made a significant contribution to human health and well-being throughout humankind's history. A significant contribution of farm animals to human health are the longstanding use of bovine and porcine for production of insulin (for treatment of diabetes), gelatin (for pharmaceutical and other purposes), as well as horse and sheep antibody against natural venoms, toxins, drugs and microbial peptides. Gelatin being the biggest animal protein consumed in human health, follows with antibodies fragments. The chronic problem of animal-derived therapeutics, especially those of high molecular weight, is the immunogenicity induction in addition to their biosafety. However, the invertebrates and lower vertebrates donate the human being a several crucial emergency saving life small-peptides or their analogs such as Refludan, Prialt, Exendin. Not only, but the farm animals are enormously using as models for novel surgical strategies, testing of biodegradable implants and sources of tissue replacements, such as skin and heart valves. Recently, they are being harnessing as bioreactor for production of biopharmaceutical related products through gene farming with efficiency far greater than any conventional microbial or cell-culture production systems. Only 16 transgenic cows would be covering the worldwide needs from human growth hormone. The transgenic, especially animal, technology would be solving a several biopharmaceutical products disadvantages, such as cost, biosafety, immunogenicity and the availability dimensions. PMID:19591041

Redwan, el-Rashdy M

2009-01-01

133

Clinical status of benzoporphyrin derivative  

NASA Astrophysics Data System (ADS)

Benzoporphyrin derivative monoacid ring A (BPD) is currently in Phase II clinical trials for the treatment of cutaneous malignancies (basal cell carcinoma and cutaneous metastases) and psoriasis. Results to date suggest that this photosensitizer has potential in both of these areas. Recently, a clinical trial with BPD was initiated for the treatment of age related macular degeneration, a neovascular condition in the eye which leads to blindness. BPD is a lipophilic photosensitizer which is rapidly taken up by activated cells and the vascular endothelium of neovasculature. The PDT effects seen with BPD appear to be a combination of vascular occlusion and direct killing of target cells. Since many diseases involve either activated cells and/or neovasculature, PDT with photosensitizer with characteristics like those of BPD, has applications far wider than oncology. A new area of interest involving photosensitizers is that of immune modulation. A number of photosensitizers have been shown to effect immune modulation in animal models of immune dysfunction including autoimmunity (rheumatoid arthritis, lupus), cutaneous hypersensitivity and allografts. BPD and PHOTOFRINR have both been shown to be effective in ameliorating arthritic symptoms in a number of animal models. The mechanisms by which immune modulation is affected in these studies still remains to be resolved.

Levy, Julia G.; Chan, Agnes H.; Strong, H. Andrew

1996-01-01

134

Satellite-Derived Management Zones  

NASA Technical Reports Server (NTRS)

The term "satellite-derived management zones" (SAMZ) denotes agricultural management zones that are subdivisions of large fields and that are derived from images of the fields acquired by instruments aboard Earth-orbiting satellites during approximately the past 15 years. "SAMZ" also denotes the methodology and the software that implements the methodology for creating such zones. The SAMZ approach is one of several products of continuing efforts to realize a concept of precision agriculture, which involves optimal variations in seeding, in application of chemicals, and in irrigation, plus decisions to farm or not to farm certain portions of fields, all in an effort to maximize profitability in view of spatial and temporal variations in the growth and health of crops, and in the chemical and physical conditions of soils. As used here, "management zone" signifies, more precisely, a subdivision of a field within which the crop-production behavior is regarded as homogeneous. From the perspective of precision agriculture, management zones are the smallest subdivisions between which the seeding, application of chemicals, and other management parameters are to be varied. In the SAMZ approach, the main sources of data are the archives of satellite imagery that have been collected over the years for diverse purposes. One of the main advantages afforded by the SAMZ approach is that the data in these archives can be reused for purposes of precision agriculture at low cost. De facto, these archives contain information on all sources of variability within a field, including weather, crop types, crop management, soil types, and water drainage patterns. The SAMZ methodology involves the establishment of a Web-based interface based on an algorithm that generates management zones automatically and quickly from archival satellite image data in response to requests from farmers. A farmer can make a request by either uploading data describing a field boundary to the Web site or else drawing the boundary on a reference image. Hence, a farmer can start to engage in precision farming shortly after gaining access to the Web site, without the need for incurring the high costs of conventional precision-agriculture data-collection practices that include collecting soil samples, mapping electrical conductivity of soil, and compiling multiyear crop-yield data. Given the boundary of a field, a SAMZ server computes the zones within the field in a three-stage process. In the first stage, a vector-valued image of the field is constructed by assembling, from the archives, the equivalent of a stack of the available images of the field (see figure). In the second stage, the vector-valued image is analyzed by use of a wavelet transform that detects spatial variations considered significant for precision farming while suppressing small-scale heterogeneities that are regarded as insignificant. In the third stage, a segmentation algorithm assembles the zones from smaller regions that have been identified in the wavelet analysis.

Lepoutre, Damien; Layrol, Laurent

2005-01-01

135

Consensus or Data Derived Anatomical Severity Scoring?  

PubMed Central

We aimed to compare the predictive accuracy of consensus derived and data derived injury severity scores when considered alone and in combination with age and physiological status. Analyses were based on 25,111 patients. The predictive validity of each severity score was evaluated in logistic regression models predicting in hospital mortality using measures of discrimination and calibration. Data derived scores had consistently better predictive accuracy than consensus derived scores in univariate models (p<0.0001) but very little difference between scores was observed in models including information on age and physiological status. Data derived scores provide more accurate mortality prediction than consensus derived scores when only anatomic injury severity is considered but offer little advantage if age and physiological status are taken into account.

Moore, Lynne; Lavoie, Andre; Le Sage, Natalie; Bergeron, Eric

2006-01-01

136

Primary ear fibroblast derivation from mice.  

PubMed

Mouse embryonic fibroblasts (MEFs) are commonly utilized as a primary cell culture model and have several advantages over other types of ex vivo-derived cells. However, the successful generation of MEFs is time consuming and requires a certain level of mouse expertise to successfully complete. Thus, primary ear-derived fibroblasts offer an acceptable alternative to MEFs. Fibroblasts derived from the pinna of adult mice are easily attainable with minimal skill, proliferate rapidly, and are easy to manipulate. Likewise, because they are derived from adult mice, other organs can be concurrently harvested for the isolation of additional types of primary cells. Similar to MEFs, ear fibroblasts are an excellent ex vivo model system to study mechanisms associated with virus infection and produce a diverse array of inflammatory mediators, such as cytokines and interferon. Here, we describe a highly versatile and simple method for the derivation, maintenance, and viral challenge of primary ear-derived fibroblasts from mice. PMID:23824888

Moore, Chris B; Allen, Irving C

2013-01-01

137

A subspace iteration for eigenvector derivatives  

NASA Technical Reports Server (NTRS)

An iterative procedure for calculating eigenvector derivatives has been developed based on the subspace iteration concept. The basic formulation is derived directly from the first variation of the resulting equations of subspace iteration for solving eigenvalue problems. Since the basic formulation conserves the convergence properties of the original subspace iteration for eigen-problems, an overrelaxation scheme similar to Bathe's approach is employed to accelerate the subspace iteration process for calculating eigenvector derivatives.

Ting, T.

1992-01-01

138

Anisotropic higher derivative gravity and inflationary universe  

NASA Astrophysics Data System (ADS)

Stability analysis of the Kantowski-Sachs type universe in pure higher derivative gravity theory is studied in detail. The nonredundant generalized Friedmann equation of the system is derived by introducing a reduced one-dimensional generalized Kantowski-Sachs type action. Existence and stability of inflationary solution in the presence of higher derivative terms are also studied in detail. Implications to the choice of physical theories are discussed in detail in this paper.

Kao, W. F.

2006-08-01

139

Adsorption and desorption of cellulose derivatives  

Microsoft Academic Search

Cellulose derivatives, in particular carboxymethyl cellulose (CMC) are used in many (industrial) applications. The aim of this work is to obtain insight into the adsorption mechanism of cellulose derivatives on solid-liquid interfaces.In chapter 1<\\/strong> of this thesis we discuss some applications of cellulose derivatives. Application of CMC in pelleting of iron ore and in papermaking and the role of adsorption

C. W. Hoogendam

1998-01-01

140

Cytotoxic activities of some novel benzhydrylpiperazine derivatives.  

PubMed

This study presents the synthesis of nineteen 1-(substitutedbenzoyl)-4-benzhydrylpiperazine and 1-[(substitutedphenyl)sulfonyl]-4-benzhydrylpiperazine derivatives. In vitro cytotoxic activities of the compounds were screened against hepatocellular (HUH-7), breast (MCF-7) and colorectal (HCT-116) cancer cell lines by sulphorhodamine B assay. Among the test compounds, benzamide derivatives had high cytotoxic activity whereas sulfonamide derivatives showed variable 50% growth inhibition (GI50). PMID:23447090

Gurdal, E E; Yarim, M; Durmaz, I; Cetin-Atalay, R

2013-03-01

141

Mantle derived economic sulfide mineralization?  

NASA Astrophysics Data System (ADS)

Sulfide ores of the unique Pt-Cu-Ni Noril'sk deposits are characterized by heavy sulfur isotopic composition (d34S = 6-18 ‰ ; Grinenko, 1985). These data are traditionally explained by the crustal contamination of the mantle melts by Devonian sedimentary rocks with anhydrites at certain depths or in a chamber of crystallization (Naldrett, 1992; Li et al., 2009). However, data on the distribution of major and trace elements and isotopic composition (their eNd, 87Sr/86Sr, d34S) in the contact zones of the intrusions with the host rocks are at variance with any significant in-situ contamination. Moreover , the mechanism of the "digestion" of this high-temperature material (Tm = 1430ºC) by the lower temperature magma (1250ºC) has never been analyzed and questioned. Our pioneering data on the sulfur radiogenic isotopes in the anhydrite are in conflict with the hypothesis that this mineral could serve as a sulfur source for the Noril'sk ores. The fact that the average composition of the intrusions is independent on the stratigraphic setting of these intrusions, which can be hosted by limestone, sandstone, and/or basalt, provides further support for the idea that no assimilation took place at the depths of the chambers in which the melts crystallized.The reason for the heavy sulfur isotopic composition of ores in the Noril'sk district is still uncertain. Last data obtained on the sulfur isotopic composition of basalts and ores from some intrusions in the Taimyr Peninsula likely provide a clue to this problem. The highest d34S values in rocks of all of the trap formations were detected in the Gudchikhinsky picrites (d34S = +8,7; Ripley et al., 2003) formed from a primitive mantle magma. They are geochemically similar to the rocks from the Dyumtaleysky Massif (d34S = 12.2; Krivolutskaya and Gongalsky, 2013) which crystallized from a primitive mantle-derived magma (with no Ta-Nb and Pb anomalies and high Gd/Yb ratio) too. This intrusion comprises economic important sulfide ores with geochemical and mineralogical characteristics similar to unique Noril'sk deposits - Talnakh, Okty'abr sky and Norilsk 1. The features of the Dyumtaleysky massif can be explained by its origin from an unusual sulfide-bearing mantle source that had sulfides through earlier crustal-mantle interaction. These data support that the mantle source of magmas in the Noril'sk district was enriched in the heavy sulfur isotope. It is the age difference that could be responsible for the unusual composition of the Noril'sk ores, because the mantle source in the Early Mesozoic was remarkably different from that in the Proterozoic one, when practically all Cu-Ni deposits worldwide were produced.

Krivolutskaya, Nadezda; Gongalskiy, Bronislav; Svirskaya, Natalia

2014-05-01

142

Deriving the Area of a Circle.  

ERIC Educational Resources Information Center

Argues that the derivation of the area of a circle using integral calculus is invalid. Describes the derivation of the area of a circle when the formula is not known by inscribing and circumscribing the circle with regular polygons whose areas converge to the same number. (MDH)

Austin, Joe Dan

1992-01-01

143

Few Fractional Order Derivatives and Their Computations  

ERIC Educational Resources Information Center

This work presents an introductory development of fractional order derivatives and their computations. Historical development of fractional calculus is discussed. This paper presents how to obtain computational results of fractional order derivatives for some elementary functions. Computational results are illustrated in tabular and graphical…

Bhatta, D. D.

2007-01-01

144

Fruit and vegetable-derived compositions  

US Patent & Trademark Office Database

This invention provides fruit and vegetable-derived compositions comprising a fruit or vegetable derivative of inter alia, at least one Beta, Capsicum and Malus species, wherein the composition is at a pH in the range of about 3 to about 6.5. The invention further provides for process for the production of the same and uses thereof.

2014-03-18

145

Hematoporphyrin derivatives: an oligomeric composition study.  

PubMed

The oligomeric composition of HpD, Photofrin II and other hematoporphyrin derivatives useful for the diagnosis and therapy of tumors has been studied. Gel chromatographic procedures were used that excluded porphyrin aggregation. Photofrin and hematoporphyrin derivatives were shown to contain different quantities of monomer, dimer and other oligomeric porphyrins. PMID:2107292

Mironov, A F; Nizhnik, A N; Nockel, A Y

1990-01-01

146

Design and synthesis of new vancomycin derivatives.  

PubMed

A set of vancomycin derivatives with lipid chain attached via a glyceric acid linker was designed and synthesized. A concise synthesis towards these derivatives was developed and the IC50s of these new lipoglycopeptides were tested. Some of them showed very potent activity against both vancomycin sensitive and resistant strains. PMID:24751442

Gu, Wen; Chen, Bei; Ge, Min

2014-05-15

147

Derive Workshop Matrix Algebra and Linear Algebra.  

ERIC Educational Resources Information Center

This document presents the course content for a workshop that integrates the use of the computer algebra system Derive with topics in matrix and linear algebra. The first section is a guide to using Derive that provides information on how to write algebraic expressions, make graphs, save files, edit, define functions, differentiate expressions,…

Townsley Kulich, Lisa; Victor, Barbara

148

Meson spectroscopy with derivative quark sources  

Microsoft Academic Search

We present results for masses of light mesons obtained with the variational method using an enhanced basis of interpolating field operators with different quark smearings. The interpolators are constructed from Jacobi-smeared quarks of a Gaussian type as well as from derivative quark sources obtained by a covariant derivative acting on the Gaussian sources. For our analysis we use quenched gauge

Christof Gattringer; Leonid Ya. Glozman; C. B. Lang; Daniel Mohler; Sasa Prelovsek

2007-01-01

149

Understanding the Derivative through the Calculus Triangle  

ERIC Educational Resources Information Center

Typical treatments of the derivative do not clearly convey the idea that the derivative function represents the original function's rate of change. Revealing the relationship between a function and its rate-of-change function for static values of "x" does not facilitate productive ways of thinking about generating the rate-of-change function or…

Weber, Eric; Tallman, Michael; Byerley, Cameron; Thompson, Patrick W.

2012-01-01

150

Smoothing splines: Regression, derivatives and deconvolution  

NASA Technical Reports Server (NTRS)

The statistical properties of a cubic smoothing spline and its derivative are analyzed. It is shown that unless unnatural boundary conditions hold, the integrated squared bias is dominated by local effects near the boundary. Similar effects are shown to occur in the regularized solution of a translation-kernel intergral equation. These results are derived by developing a Fourier representation for a smoothing spline.

Rice, J.; Rosenblatt, M.

1982-01-01

151

ADIFOR --- Generating Derivative Codes from Fortran Programs  

Microsoft Academic Search

. The numerical methods employed in the solution of many scientific computing problems require the computationof derivatives of a function f : Rn!Rm. Both the accuracy and the computationalrequirements of the derivative computationare usually of critical importance for the robustness and speed of the numerical solution. ADIFOR (Automatic DifferentiationIn FORtran) is a source transformation tool that accepts Fortran 77 code

1991-01-01

152

Theory of Financial Risk and Derivative Pricing  

Microsoft Academic Search

Summarizing market data developments, some inspired by statistical physics, this book explains how to better predict the actual behavior of financial markets with respect to asset allocation, derivative pricing and hedging, and risk control. Risk control and derivative pricing are major concerns to financial institutions. The need for adequate statistical tools to measure and anticipate amplitude of potential moves of

Jean-Philippe Bouchaud; Marc Potters

2004-01-01

153

Lie derivations of certain CSL algebras  

Microsoft Academic Search

It is shown that each Lie derivation on a reflexive algebra, whose lattice is completely distributive and commutative, can\\u000a be uniquely decomposed into the sum of a derivation and a linear mapping with image in the center of the algebra.

Fangyan Lu

2006-01-01

154

Derived Categories and Zero-Brane Stability.  

National Technical Information Service (NTIS)

We define a particular class of topological field theories associated to open strings and prove the resulting D-branes and open strings form the bounded derived category of coherent sheaves. This derivation is a variant of some ideas proposed recently by ...

A. Lawrence

2001-01-01

155

Spanning and derivative-security valuationq  

Microsoft Academic Search

This article provides the economic foundations for valuing derivative securities. In particular, it establishes how the characteristic function (of the future uncertainty) is basis augmenting and spans the payo! universe of most, if not all, derivative assets. From the characteristic function of the state-price density, it is possible to analytically price options on any arbitrary transformation of the underlying uncertainty.

Gurdip Bakshi; Dilip Madan

1999-01-01

156

Novel Aflatoxin Derivatives and Protein Conjugates  

Microsoft Academic Search

Aflatoxins, a group of structurally related mycotoxins, are well known for their toxic and carcinogenic effects in humans and animals. Aflatoxin derivatives and protein conjugates are needed for diverse analytical applications. This work describes a reliable and fast synthesis of novel aflatoxin derivatives, purification by preparative HPLC and characterisation by ESI-MS and one- and two-dimensional NMR. Novel aflatoxin bovine serum

Christian Cervino; Dietmar Knopp; Michael G. Weller; Reinhard Niessner

2007-01-01

157

Drug laws and the 'derivative' problem.  

PubMed

The concept of a 'derivative' is used widely in chemistry, where its precise meaning depends on the circumstances. However, numerous examples of derivative also occur in domestic drugs legislation, some of which stem from the 1961 United Nations Single Convention on Narcotic Drugs. There is a commonly held view that only 'first-order' derivatives should be considered: substances that can be created from a parent structure in a single chemical reaction. In other words, 'derivatives of derivatives' are excluded. However, some substances related to ecgonine (e.g. 2-carbomethoxytropinone) are clearly convertible to cocaine, even though this may require more than one reaction step. It follows that 2-carbomethoxytropinone is a controlled drug, a situation that most chemists would regard as perverse. A more extreme example of the complexity of 'derivative' is shown by the conversion of thebaine to buprenorphine. Even though this requires six or more stages, the US Drug Enforcement Administration successfully argued in a 1986 case that for the purposes of the Controlled Substances Act, the number of steps required was irrelevant; buprenorphine was a derivative of thebaine. Because the term derivative is rarely defined in statutes, the legal status of some substances, such as 2-bromo-LSD, is uncertain. Although a number of definitions of derivative can be found in the chemical literature, no single definition is adequate to describe all situations where it occurs in legislation. Unless qualified, it is suggested that the term derivative should be avoided in any future legislation. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23949903

King, Leslie A; Ujváry, István; Brandt, Simon D

2014-07-01

158

Aminoalkylcarbamyl Derivatives of Forskolin as Intermediates for the Synthesis of Useful Forskolin Derivatives.  

National Technical Information Service (NTIS)

The subject matter of the invention relates to aminoalkylcarbamates of forskolin and the uses of these compounds. Specifically, the aminoalkylcarbamates may be utilized as intermediates in the synthesis of forskolin derivatives. The final derivatives or a...

K. B. Seamon J. Robbins A. Laurenza

1990-01-01

159

An [11]cytochalasin derivative from the marine-derived fungus Xylaria sp. PSU-F100.  

PubMed

A new [11]cytochalasin derivative, xylarisin (1), was isolated from the marine-derived fungus Xylaria sp. PSU-F100 along with six known metabolites: three mellein derivatives (2-4), one pyrone derivative (5) and two carboxylic acids (6,7). The structure and stereochemistry of 1 were determined by NMR and X-ray diffraction analyses. All isolated compounds showed mild antibacterial activity against standard Staphylococcus aureus ATCC 25923 and methicillin-resistant strain. PMID:19952454

Rukachaisirikul, Vatcharin; Khamthong, Nanthaphong; Sukpondma, Yaowapa; Pakawatchai, Chaveng; Phongpaichit, Souwalak; Sakayaroj, Jariya; Kirtikara, Kanyawim

2009-12-01

160

Theory of Financial Risk and Derivative Pricing  

NASA Astrophysics Data System (ADS)

Summarizing market data developments, some inspired by statistical physics, this book explains how to better predict the actual behavior of financial markets with respect to asset allocation, derivative pricing and hedging, and risk control. Risk control and derivative pricing are major concerns to financial institutions. The need for adequate statistical tools to measure and anticipate amplitude of potential moves of financial markets is clearly expressed, in particular for derivative markets. Classical theories, however, are based on assumptions leading to systematic (sometimes dramatic) underestimation of risks. First edition Hb (2000): 0-521-78232-5

Bouchaud, Jean-Philippe; Potters, Marc

2004-02-01

161

Synthesis of Sterically Hindered Polychlorinated Biphenyl Derivatives  

PubMed Central

A series of sterically hindered (methoxylated) polychlorinated biphenyl derivatives was synthesized using the Suzuki and the Ullmann coupling reaction. The Suzuki coupling with Pd(dba)2/2-dicyclohexylphosphino-2?,6?-dimethoxybiphenyl (DPDB) gave better yields (65–98%) compared to the classic Ullmann coupling reaction (20–38%). Despite the reactive catalyst system, no significant coupling with aromatic chlorine substituents was observed. Crystal structure analysis of four PCB derivatives revealed solid state dihedral angles ranging from 69.7° to 81.0°, which indicates that these highly ortho substituted PCB derivatives have some conformational flexibility.

Joshi, S. N.; Vyas, S. M.; Duffel, M. W.; Parkin, S.; Lehmler, H.-J.

2011-01-01

162

Synthesis of Hemigossypol and its Derivatives  

PubMed Central

Hemigossypol (3), a sesquiterpene natural product, was previously isolated from Gossypium barbadense and was shown to display improved anti-fungal activity compared to gossypol (1), the disesquiterpene dimer of hemigossypol (3). Gossypol exhibits multiple biological activities. In order to study whether hemigossypol and it derivatives retain the various bioactivities of gossypol, we developed a short and convenient synthetic scheme to synthesize hemigossypol. This is the first de novo synthesis of this natural product. In addition derivatives of hemigossypol with various 2,5-alkyl substituents were synthesized. Modification of the synthetic scheme also afforded the natural product hemigossylic lactone (4) and its 2,5-substituted derivatives.

Wei, Jun; Vander Jagt, David L.; Royer, Robert E.; Deck, Lorraine M.

2012-01-01

163

Water Soluble Derivatives of Frederimacycin A.  

National Technical Information Service (NTIS)

The present invention is related generally to fredericamycin A. More particularly, the present invention is related to new, water soluble, biologically active derivatives of fredericamycin A and a process for making the same.

R. Misra

1986-01-01

164

Derivatives of the Stochastic Growth Rate  

PubMed Central

We consider stochastic matrix models for population driven by random environments which form a Markov chain. The top Lyapunov exponent a, which describes the long-term growth rate, depends smoothly on the demographic parameters (represented as matrix entries) and on the parameters that define the stochastic matrix of the driving Markov chain. The derivatives of a — the “stochastic elasticities” — with respect to changes in the demographic parameters were derived by Tuljapurkar (1990). These results are here extended to a formula for the derivatives with respect to changes in the Markov chain driving the environments. We supplement these formulas with rigorous bounds on computational estimation errors, and with rigorous derivations of both the new and the old formulas.

Steinsaltz, David; Tuljapurkar, Shripad; Horvitz, Carol

2011-01-01

165

Deriving Linear Transformations in Three Dimensions  

Microsoft Academic Search

This article presents a general technique for solving elementary algebraic problems that arise in 3D geometry and then applies this method to derive explicit formulas for many of the linear transformations used in the standard 3D graphics pipeline.

Ron Goldman

2003-01-01

166

Catalytic combustion of coal-derived liquids  

NASA Technical Reports Server (NTRS)

A noble metal catalytic reactor was tested with three grades of SRC 2 coal derived liquids, naphtha, middle distillate, and a blend of three parts middle distillate to one part heavy distillate. A petroleum derived number 2 diesel fuel was also tested to provide a direct comparison. The catalytic reactor was tested at inlet temperatures from 600 to 800 K, reference velocities from 10 to 20 m/s, lean fuel air ratios, and a pressure of 3 x 10 to the 5th power Pa. Compared to the diesel, the naphtha gave slightly better combustion efficiency, the middle distillate was almost identical, and the middle heavy blend was slightly poorer. The coal derived liquid fuels contained from 0.58 to 0.95 percent nitrogen by weight. Conversion of fuel nitrogen to NOx was approximately 75 percent for all three grades of the coal derived liquids.

Bulzan, D. L.; Tacina, R. R.

1981-01-01

167

Diagrammatic Derivation of Coleman's Vanishing Cosmological Constant.  

National Technical Information Service (NTIS)

We present an alternative derivation of Coleman's expression for cosmological constant by summing over topologies of space-time in the wormhole dominance approximation. It is pointed out that the correlation between disconnected spaces, if any, vanishes b...

A. Hosoya

1988-01-01

168

Analysis and the Derivation of Valid Objectives  

ERIC Educational Resources Information Center

Author states that "to the extent that behavioral objectives are derived from an analysis of relatively broad objectives, they can serve as valid criteria which enable our students to avoid trivia." (Author)

Tiemann, Philip W.

1973-01-01

169

Formalization and Automatic Derivation of Code Generators.  

National Technical Information Service (NTIS)

This work is concerned with automatic derivation of code generators, which translate a parse-tree-like representation of programs into sequences of instructions for a computer defined by a machine description. In pursuing this goal, the following are pres...

R. G. G. Cattell

1978-01-01

170

Synthesis of Bisbenzil Isomers and Derivatives.  

National Technical Information Service (NTIS)

The goal of this investigation was to apply the modified benzoin condensation, used successfully in the synthesis of unsubstituted para-bis(phenylglyoxyloyl) benzene, to the preparation of substituted para-derivatives as well as to the production of selec...

K. L. Paciorek T. I. Ito R. H. Kratzer

1976-01-01

171

Derivation of OH concentrations from LIMS measurements  

NASA Astrophysics Data System (ADS)

Stratospheric concentrations of OH have been derived from LIMS measurements of minor constituents. Two methods have been used. Assuming that HNO3 and NO2 are in photochemical steady state, LIMS measurements of these species, with knowledge of appropriate rate constants and a calculation of the HNO3 photolysis rate, allow nearly global fields of OH to be derived. The derived profiles show satisfactory agreement with observations. As a check on the method, OH has also been derived by calculations of its sources and sinks using LIMS measurements of H2O. The two methods agree extremely well in low latitudes. At higher latitudes the agreement is less satisfactory. This is discussed in terms of the diurnal behavior of the species and the time constant of the HNO3/NO2 equilibrium.

Pyle, J. A.; Zavody, A. M.; Harries, J. E.; Moffat, P. H.

172

Nonadditive Probabilities and Derived Strengths of Preferences.  

National Technical Information Service (NTIS)

A method is introduced to derive strength of preference revelations on consequences from ordinal preferences on acts, based on Schmeidler's approach to decision making under uncertainty. Thus, a behavioral foundation is given for the maximization of subje...

P. Wakker

1987-01-01

173

Concise Derivation of the Rotational Partition Function.  

ERIC Educational Resources Information Center

Derived is the classical partition function for the rotation of a rigid asymmetric molecule, by a transformation of variables in the phase integral circumventing the cumbersome manipulation of the canonical prescription. (Author/GA)

Hynne, F.; Andersen, Knud

1979-01-01

174

Sums and Differences vs. Integrals and Derivatives.  

ERIC Educational Resources Information Center

Offers an approach to the understanding and to the teaching of the fundamental theorem of calculus. Stresses teaching the relation between a function and its derivative and the functions themselves. (YP)

Strang, Gilbert

1990-01-01

175

Methods of Therapy with Thrombin Derived Peptides.  

National Technical Information Service (NTIS)

The present invention relates to a method for promoting cardiac tissue repair comprising administering to the cardiac tissue a therapeutically effective amount of an angiogenic thrombin derivative peptide and/or inhibiting or reducing vascular occlusion o...

D. H. Carney

2004-01-01

176

Polypeptide Derivatives of Parathyroid Hormone (PTH).  

National Technical Information Service (NTIS)

Novel parathyroid hormone (PTH) polypeptide derivatives are disclosed, as are pharmaceutical compositions containing said polypeptides, and synthetic and recombinant methods for producing said polypeptides. Also disclosed are methods for treating mammalia...

H. Juppner H. M. Kronenberg J. T. Potts T. J. Gardella

2005-01-01

177

Reactions of Pentaborane (9) and Pentaborane Derivatives.  

National Technical Information Service (NTIS)

A number of pentaborane derivatives are prepared in their (11)B and (1)H nmr spectra recorded and correlated. Assessments of alternative preparative schemes are given. An extension of the apex to base rearrangement reaction to polyalkyl pentaboranes revea...

T. Onak G. B. Dunks I. W. Search J. R. Spielman

1966-01-01

178

A New Derivation of the Logistic Distribution.  

National Technical Information Service (NTIS)

Logistic distribution is widely used in describing biological, engineering, industrial, and various other types of data. In this paper it is shown that this distribution is a special case of a compound generalized extreme value distribution which is deriv...

S. D. Dubey

1969-01-01

179

New Derivation of the Rasch Model.  

National Technical Information Service (NTIS)

The Rasch model is usually derived from statistical requirements of estimation of its parameters. The principle of 'specific objectivity' or, equivalently, 'sample independence' requires that subject parameters can be estimated independent from the item p...

E. E. Roskam P. G. W. Jansen

1983-01-01

180

Biologically active amphiphilic derivatives of chitosan  

Microsoft Academic Search

Amphiphilic N-derivatives of chitosan containing C12 alkyl and carboxyl groups were obtained. It was shown that the compounds obtained have fungicidal activity and form intermolecular\\u000a associates in solutions.

E. A. Stepnova; V. E. Tikhonov; V. G. Babak; M. A. Krayukhina; K. K. Babievskii; I. A. Yamskov

2005-01-01

181

The Electromagnetic Activity of Porphin Derivatives.  

National Technical Information Service (NTIS)

The basic objective of the research was to explore the possibilities of using porphin derivatives as model compounds in a study of structure-property and structure-reactivity relationships. The large number of porphyrin structures available, their wide ra...

A. D. Adler

1967-01-01

182

Derivation of various NONMEM estimation methods  

Microsoft Academic Search

Various estimation methods and the lack of a systematic derivation of the core objective function implemented in NONMEM for\\u000a nonlinear mixed effect modeling has caused consistent confusion and inquiry among scientists who routinely use NONMEM for\\u000a data analysis. This paper provides a detailed derivation of the objective functions for the most commonly used estimation\\u000a methods in NONMEM, such as the

Yaning Wang

2007-01-01

183

Entropic-Gravity Derivation of MOND  

NASA Astrophysics Data System (ADS)

A heuristic entropic-gravity derivation has previously been given of the gravitational two-body force of modified Newtonian dynamics (MOND). Here, it is shown that another characteristic of MOND can also be recovered, namely, the external field effect (implying a violation of the Strong Equivalence Principle). In fact, the derivation gives precisely the modified Poisson equation which Bekenstein and Milgrom proposed as a consistent nonrelativistic theory of MOND.

Klinkhamer, F. R.

184

The lexical semantics of derived statives  

Microsoft Academic Search

This paper investigates the semantics of derived statives, deverbal adjectives that fail to entail there to have been a preceding\\u000a (temporal) event of the kind named by the verb they are derived from, e.g. darkened in a darkened portion of skin. Building on Gawron’s (The lexical semantics of extent verbs, San Diego State University, ms, 2009) recent observations regarding the

Andrew Koontz-Garboden

2010-01-01

185

Arbitrage Free Price Bounds for Property Derivatives  

Microsoft Academic Search

Market frictions inhibit the perfect replication of property derivatives, and define the property spread as a price measure\\u000a in the incomplete real estate market. We identify transaction costs, transaction time, and short sale constraints as the main\\u000a frictions in this market. Based on these frictions, we set up a framework of arbitrage free price bounds for property derivatives.\\u000a In turn,

Juerg M. Syz; Paolo Vanini

2011-01-01

186

Five new eremophilane derivatives from Ligularia sagitta  

Microsoft Academic Search

Ligulasagitins A–E (1–5), five new eremophilane-derived metabolites possibly formed via a Diels–Alder reaction in the biosynthetic process, were isolated from Ligularia sagitta Maxim. Among them 1 and 2 possess a novel C19 skeleton, 4 and 5 are two novel dimeric eremophilane type derivatives. Their structures were determined by extensive spectroscopic analysis and the structure of 2 was also confirmed by

Ping-Lin Li; Chun-Ming Wang; Zhan-Xin Zhang; Zhong-Jian Jia

2007-01-01

187

Hedging gas bills with weather derivatives  

Microsoft Academic Search

Natural gas company managers concerned with customer satisfaction attempt to minimize the occurrence of extreme bills. Previously,\\u000a only price fluctuations were addressed with derivative instruments; exchange-traded weather derivatives present a means of\\u000a hedging exposure to increases in quantity of gas demanded during colder than expected winter months. We model a natural gas\\u000a company’s ability to adjust for consumer sensitivity and

Karyl B. Leggio; Donald Lien

2002-01-01

188

Development of thermally stable phosphonitrile elastomers for advanced aerospace structures  

NASA Technical Reports Server (NTRS)

Both high and low molecular weight, curable poly(fluoroalkoxy phosphazene) terpolymers were prepared. These terpolymers resulted from reaction of (Cl2PNn) polymer with alkoxides derived from CF3CH2OH and C3F7CH2OH, and an alkoxide derived from CH3CH(OH)C2H4OH. The terpolymers were crosslinked with polyisocyanates at room temperature. High molecular weight materials were converted into isocyanate prepolymers which as films underwent moisture cures at room temperature. Prepolymer solutions were stable for several days, and showed good adhesion. Also the effects of polymerization of (Cl2PN)3 were studied. Purified octachlorophosphazene, thiocyanate salts, or hydrogen chloride were employed in attempts to decrease molecular weight. Hydrogen chloride was found to be a good agent for preparation of low molecular weight poly(dichloro phosphazene).

Reynard, K. A.; Gerber, A. H.; Peterson, T.; Rose, S. H.

1973-01-01

189

Numerical derivative techniques for trajectory optimization  

NASA Technical Reports Server (NTRS)

The adoption of robust numerical optimization techniques in trajectory simulation programs has resulted in powerful design and analysis tools. These trajectory simulation/optimization programs are widely used, and a representative list includes the GTS system, the POST program, and newer collocation methods such as OTIS and FONPAC. All of these programs rely on optimization algorithms which require objective function and constraint gradient data during the iteration process. However, most trajectory optimization problems lack simple analytical expressions for these derivatives. In the general case a function evaluation involves integrating aerodynamic, propulsive, and gravity forces over multiple trajectory phases with complex control models. With the newer collocation methods, the integration is replaced by defect constraints and cubic approximations for the state. While analytic gradient expressions can sometimes be derived for trajectory optimization problems, the derivation is cumbersome, time consuming, and prone to mistakes. Fortunately, an alternate method exists for the gradient evaluation, namely finite difference approximations. In this paper some finite difference gradient techniques developed for use with the GTS system are presented. These techniques include methods for computing first and second partial derivatives of single and multiple sets of functions. A key feature of these methods is an error control mechanism which automatically adjusts the perturbation size to obtain accurate derivative values.

Hallman, Wayne P.

1990-01-01

190

Structure Activity Relationship of Brevenal Hydrazide Derivatives  

PubMed Central

Brevenal is a ladder frame polyether produced by the dinoflagellate Karenia brevis. This organism is also responsible for the production of the neurotoxic compounds known as brevetoxins. Ingestion or inhalation of the brevetoxins leads to adverse effects such as gastrointestinal maladies and bronchoconstriction. Brevenal shows antagonistic behavior to the brevetoxins and shows beneficial attributes when administered alone. For example, in an asthmatic sheep model, brevenal has been shown to increase tracheal mucosal velocity, an attribute which has led to its development as a potential treatment for Cystic Fibrosis. The mechanism of action of brevenal is poorly understood and the exact binding site has not been elucidated. In an attempt to further understand the mechanism of action of brevenal and potentially develop a second generation drug candidate, a series of brevenal derivatives were prepared through modification of the aldehyde moiety. These derivatives include aliphatic, aromatic and heteroaromatic hydrazide derivatives. The brevenal derivatives were tested using in vitro synaptosome binding assays to determine the ability of the compounds to displace brevetoxin and brevenal from their native receptors. A sheep inhalation model was used to determine if instillation of the brevenal derivatives resulted in bronchoconstriction. Only small modifications were tolerated, with larger moieties leading to loss of affinity for the brevenal receptor and bronchoconstriction in the sheep model.

Goodman, Allan; McCall, Jennifer R.; Jacocks, Henry M.; Thompson, Alysha; Baden, Daniel; Abraham, William M.; Bourdelais, Andrea

2014-01-01

191

Reactions of glycidyl derivatives with ambident nucleophiles; part 2: amino acid derivatives  

PubMed Central

A three-step procedure for the synthesis of multifunctionalized heterocycles from a pyroglutamic acid derivative, glycidyl components and anilines by nucleophilic substitution and cobalt catalysis is presented.

Dyker, Gerald; Thone, Andreas; Henkel, Gerald

2007-01-01

192

Increment of antimycobaterial activity on lichexanthone derivatives.  

PubMed

A new dihydropyranexanthone derived from the natural xanthone lichexanthone (1) was synthesised and, together with other 18 derivatives including ?-bromo and ?-aminoalkoxylxanthones (containing methyl, ethyl, propyl, tertbutylamino and piperidinyl moieties), were tested against Mycobacterium tuberculosis. Nine ?-aminoalkoxylxanthones showed good antimycobacterial activity, and their in vitro cytotoxicity was determined using VERO cells in order to calculate the selectivity index (SI). One of these nitrogenated xanthone derivatives showed very promising results, with MIC of 2.6 ?M and SI of 48. This MIC is comparable to values found in "first and second line" drugs commonly used to treat TB. In order to understand better about this compound, it was evaluated together with two other ones that showed good SI, against resistant clinical strains of M. tuberculosis to verify the existence of cross-resistance. A chemometrical approach was useful to establish a pattern of antitubercular activity among the group of ?-aminoalkoxylxanthones, according to some structural and chemical features. PMID:23106287

Micheletti, Ana Camila; Honda, Neli Kika; Pavan, Fernando R; Leite, Clarice Q F; Matos, Maria de Fatima Cepa; Perdomo, Renata Trentin; Bogo, Danielle; Alcantara, Glaucia Braz; Beatriz, Adilson

2013-11-01

193

Synthesis and properties of novel psoralen derivatives  

SciTech Connect

The authors have synthesized a set of new trimethylpsoralen derivatives that are characterized by a chain extending from the 4'-position of the furan ring and linked to this ring by an aminomethylene group. The nature of the side chain can be varied widely. In these derivatives, the chains contain either amino or ethylene oxide units for enhanced water solubility and allow the introduction of a thiol or amine group to nucleic acids. These compounds represent the first set of thiolated psoralen derivatives, and their usefulness is demonstrated in several nucleic acid cross-linking experiments. The reagents can be used to create both intraduplex reversible cross-links between the two single-strand partners in a DNA double helix and interduplex reversible cross-links between two DNA double helices.

Goldenberg, M.; Welsh, J.; Haas, R.; Rideout, D.C.; Cantor, C.R.

1988-09-06

194

Electrical derivative measurement of quantum cascade lasers  

NASA Astrophysics Data System (ADS)

The electrical derivative characteristics of quantum cascade lasers (QCLs) are investigated to test the QCL threshold, leakage current, and possibly explore carrier transport. QCL thresholds can be identified by searching for the slope peak of the first derivative of the I-V curves and can be further confirmed with its alignment to the peak of the second derivative of the I-V curves. Leakage current in QCLs with oxide-blocked ridge waveguides and buried heterostructure (BH) waveguides are studied and compared. The oxide-blocking structures provide the lowest leakage current although the capped-mesa-BH (CMBH) QCLs provide the toughest durability under highly stressful operations. The leakage current of CMBH QCLs are also compared at different temperatures.

Guo, Dingkai; Cheng, Liwei; Chen, Xing; Choa, Fow-Sen; Fan, Jenyu; Worchesky, Terry

2011-02-01

195

Conversion of tomato saponins to pregnane derivatives.  

PubMed

Here reports new conversions methods of tomato saponins, esculeoside A (1) and a mixture of esculeosides B-1 (2) and B-2 (3), (the latter two were obtained from tomato cans) into pregnane derivative (5) by an alkal treatment followed by acid treatment. Compound 1 or a mixture of 2 and 3 were each refluxed with 1?N KOH to afford a characteristic pyridine steroidal glycoside (4), which was then treated with 2?N HCl-MeOH to afford a pregnane derivative, 3?-hydroxy-5?-pregn-16-en-20-one (5). The results of the above two reactions indicated that tomato saponins are chemically closely related to pregnane hormones. We assume that the assimilated tomato saponins via the small intestine are metabolized into pregnane derivatives, demonstrating various bioactivities such as anti-cancer, anti-osteoporosis, and anti-menopausal disorder activities. PMID:24789931

Nohara, Toshihiro; Manabe, Hideyuki; Fujiwara, Yukio; Ikeda, Tsuyoshi; Ono, Masateru; Murakami, Kotaro; Nakano, Daisuke; Kinjo, Junei; Kajimoto, Tetsuya

2014-01-01

196

[Antiamyloid properties of fullerene C60 derivatives].  

PubMed

A comparative estimation of the ability of complexes of fullerene C60 with polyvinylpyrrolidone and fullerene C60 derivatives (the sodium salt of the polycarboxylic derivative of fullerene C60, sodium fullerenolate), has been carried out. The fullerenes destroyed amyloid fibrils of the Abeta(1-42) peptide of the brain and the muscle X-protein. A study of the effect of fullerenes on muscle actin showed that complexes of fullerene C60 with polyvinylpyrrolidone and sodium fullerenolate did not prevent the filament formation of actin, nor did they destroy its filaments in vitro. Conversely, sodium salt of the polycarboxylic derivative of fullerene C60 destroyed actin filaments and prevented their formation. It was concluded that sodium fullerenolate and complexes of fullerene C60 with polyvinylpyrrolidone are the most effective antiamyloid compounds among the fullerenes examined. PMID:22873064

Bobylev, A G; Shpagina, M D; Bobyleva, L G; Okuneva, A D; Piotrovski?, L B; Podlubnaia, Z A

2012-01-01

197

Geometric derivation of the quantum speed limit  

SciTech Connect

The Mandelstam-Tamm and Margolus-Levitin inequalities play an important role in the study of quantum-mechanical processes in nature since they provide general limits on the speed of dynamical evolution. However, to date there has been only one derivation of the Margolus-Levitin inequality. In this paper, alternative geometric derivations for both inequalities are obtained from the statistical distance between quantum states. The inequalities are shown to hold for unitary evolution of pure and mixed states, and a counterexample to the inequalities is given for evolution described by completely positive trace-preserving maps. The counterexample shows that there is no quantum speed limit for nonunitary evolution.

Jones, Philip J.; Kok, Pieter [Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2010-08-15

198

Cyclodextrin derivatives as anti-infectives.  

PubMed

Cyclodextrin derivatives can be utilized as anti-infectives with pore-forming proteins as the targets. The highly efficient selection of potent inhibitors was achieved because per-substituted cyclodextrins have the same symmetry as the target pores. Inhibitors of several bacterial toxins produced by Bacillus anthracis, Staphylococcus aureus, Clostridium perfringens, Clostridium botulinum, and Clostridium difficile were identified from a library of ?200 CD derivatives. It was demonstrated that multi-targeted inhibitors can be found using this approach and could be utilized for the development of broad-spectrum drugs against various pathogens. PMID:24011515

Karginov, Vladimir A

2013-10-01

199

Special relativity derived from spacetime magma.  

PubMed

We present a derivation of relativistic spacetime largely untethered from specific physical considerations, in constrast to the many physically-based derivations that have appeared in the last few decades. The argument proceeds from the inherent magma (groupoid) existing on the union of spacetime frame components [Formula: see text] and Euclidean [Formula: see text] which is consistent with an "inversion symmetry" constraint from which the Minkowski norm results. In this context, the latter is also characterized as one member of a class of "inverse norms" which play major roles with respect to various unital [Formula: see text]-algebras more generally. PMID:24959889

Greensite, Fred

2014-01-01

200

Polyphenol derivatives - potential regulators of neutrophil activity  

PubMed Central

The study provides new information on the effect of natural polyphenols (derivatives of stilbene – resveratrol, pterostilbene, pinosylvin and piceatannol and derivatives of ferulic acid – curcumin, N-feruloylserotonin) on the activity of human neutrophils in influencing oxidative burst. All the polyphenols tested were found to reduce markedly the production of reactive oxygen species released by human neutrophils on extra-and intracellular levels as well as in cell free system. Moreover, pinosylvin, curcumin, N-feruloylserotonin and resveratrol decreased protein kinase C activity involved in neutrophil signalling and reactive oxygen species production. Our results suggest that due to their anti-neutrophil activity, the polyphenols tested might be attractive candidates in therapeutic development.

Perecko, Tomas; Nosal, Radomir; Harmatha, Juraj; Smidrkal, Jan; Jancinova, Viera

2012-01-01

201

Special Relativity Derived from Spacetime Magma  

PubMed Central

We present a derivation of relativistic spacetime largely untethered from specific physical considerations, in constrast to the many physically-based derivations that have appeared in the last few decades. The argument proceeds from the inherent magma (groupoid) existing on the union of spacetime frame components and Euclidean which is consistent with an “inversion symmetry” constraint from which the Minkowski norm results. In this context, the latter is also characterized as one member of a class of “inverse norms” which play major roles with respect to various unital -algebras more generally.

Greensite, Fred

2014-01-01

202

Terpenes from Marine-Derived Fungi  

PubMed Central

Terpenes from marine-derived fungi show a pronounced degree of structural diversity, and due to their interesting biological and pharmacological properties many of them have aroused interest from synthetic chemists and the pharmaceutical industry alike. The aim of this paper is to give an overview of the structural diversity of terpenes from marine-derived fungi, highlighting individual examples of chemical structures and placing them in a context of other terpenes of fungal origin. Wherever possible, information regarding the biological activity is presented.

Ebel, Rainer

2010-01-01

203

New coumarin derivatives as carbonic anhydrase inhibitors.  

PubMed

In the current study, a series of 4-chloromethyl-7-hydroxy-coumarin derivatives containing imidazolium, benzimidazolium, bisbenzimidazolium and quaternary ammonium salts were synthesized, characterized and the inhibition effects of the derivatives on human carbonic anhydrases (hCA I and hCA II) were investigated as in vitro. Structures of these coumarins were confirmed by FT-IR, (1)H NMR, (13)C NMR and LC-MS analyses. Structure activity relationship study showed that 3d (IC50: 79 ?M for hCA I and 88 ?M for hCA II) performed higher inhibitory activity than others. PMID:23656671

Karata?, Mert Olgun; Alici, Bülent; Cakir, Umit; Cetinkaya, Engin; Demir, Dudu; Ergün, Adem; Gençer, Nahit; Arslan, Oktay

2014-06-01

204

Synthesis and antifungal properties of papulacandin derivatives  

PubMed Central

Summary Derivatives of an antifungal agent that targets the ?-(1,3)-D-glucan synthase, papulacandin D, were synthesized and tested for activity. The papulacandin D structure contains a challenging benzannulated spiroketal unit, which is introduced in a palladium-catalyzed cross-coupling reaction of a glycal silanolate and an aryl iodide followed by an oxidative spiroketalization. Four different variants were made, differing in the nature of the acyl side chain with respect to the length, and in the number and stereochemistry of the double bonds. Moderate biological activity was observed for the derivatives with a side chain based on palmitic acid and linoleic acid.

van der Kaaden, Marjolein; Breukink, Eefjan

2012-01-01

205

Water-soluble derivatives of 1 -tetrahydrocannabinol.  

PubMed

Delta1-Tetrahydrocannabinol, which is resinous and insoluble in water and therefore difficult to study pharmacologically, can be converted to a watersoluble derivative without loss of its biological activity. This has been achieved by preparing esters bearing a nitrogen moiety with the use of carbodiimide as the condensing agent. The availability of such water-soluble derivatives will allow the evaluation of Delta1-tetrahydrocannabinol in self-administration studies in monkeys for its addiction liability potential in man. This technique of water solubilization is also applicable to other compounds of chemical and biological significance. PMID:5043146

Zitko, B A; Howes, J F; Razdan, R K; Dalzell, B C; Dalzell, H C; Sheehan, J C; Pars, H G; Dewey, W L; Harris, L S

1972-08-01

206

Structural studies of 4-aminoantipyrine derivatives  

NASA Astrophysics Data System (ADS)

Reaction of 4-aminoantipyrine with acetylacetone, ethyl acetoacetate, benzoyl isothiocyanate, phenyl isothiocyanate, maleic anhydride and methoxymethylene Meldrum's acid afforded a series of new antipyrine derivatives. The antibacterial activity of the synthesized compounds against Micrococcus luteus ATCC 9341, Staphilococcus aureus ATCC 29737, and Escherichia coli ATCC 8739 was evaluated and the minimal inhibitory concentration determined. Modest activity was found only to the maleamic acid obtained from the reaction of 4-aminoantipyrine and maleic anhydride. 1H NMR investigation of this maleamic acid showed that it is slowly converted to the corresponding toxic maleimide. The structures of three derivatives were determined by X-ray diffraction analysis.

Cunha, Silvio; Oliveira, Shana M.; Rodrigues, Manoel T.; Bastos, Rodrigo M.; Ferrari, Jailton; de Oliveira, Cecília M. A.; Kato, Lucília; Napolitano, Hamilton B.; Vencato, Ivo; Lariucci, Carlito

2005-10-01

207

Neutron stars in the derivative coupling model  

SciTech Connect

Properties of neutron stars derived from the hybrid derivative coupling model of nuclear field theory are studied. Generalized beta equilibrium with all baryon types to convergence is allowed. Hyperon couplings compatible with the inferred binding energy of the lambda hyperon in saturated nuclear matter predict a large hyperon population, with neutrons having a bare majority population in a 1.5{ital M}{sub {circle dot}} neutron star. Among the properties studied are the limits on rotation imposed by gravitation-radiation-reaction instabilities as moderated by viscosity. These instabilities place a lower limit on rotational periods of neutron and hybrid stars of about 1 ms.

Glendenning, N.K.; Weber, F. (Nuclear Science Division, Lawrence Berkeley Laboratory, University of California, One Cyclotron Road, Berkeley, California 94720 (United States)); Moszkowski, S.A. (University of California at Los Angeles, Department of Physics, Los Angeles , California 90024 (United States))

1992-02-01

208

Effects of guanidine derivatives on mitochondrial function  

PubMed Central

Long chain free fatty acids interfere with the inhibitory action of phenethylbiguanide and related compounds on mitochondrial respiration in vitro. This interference depends on binding of fatty acids to mitochondria and diminishes with decreasing chain length. Reversal of guanidine-derivative inhibition by fatty acids differs from that caused by dinitrophenol in that the effect of fatty acid is achieved without alteration in coupling or respiratory control. The binding of phenethylbiguanide to mitochondria is inhibited by both fatty acid and dinitrophenol. Serum albumin potentiates the inhibitory potency of guanidine derivatives, probably by removing endogenous mitochondrial free fatty acids.

Davidoff, Frank

1968-01-01

209

Elevation Derivatives for Mojave Desert Tortoise Habitat  

USGS Publications Warehouse

This report describes the methods used to derive various elevation-derivative grids that were inputted to the Mojave Desert Tortoise Habitat model (L. Gass and others, unpub. data). These grids, which capture information on surface roughness and topographic characteristics, are a subset of the environmental datasets evaluated for the tortoise habitat model. This habitat model is of major importance to the U.S. Fish and Wildlife Service, which is charged with management of this threatened population, including relocating displaced tortoises to areas identified as suitable habitat.

Wallace, Cynthia S. A.; Gass, Leila

2008-01-01

210

32 CFR 2400.14 - Use of derivative classification.  

Code of Federal Regulations, 2010 CFR

...OFFICE OF SCIENCE AND] [Subpart C - Derivative Classification] [Sec. 2400.14 - Use of derivative classification.] 32 NATIONAL DEFENSE...O. 12356; OFFICE OF SCIENCE AND Derivative Classification Sec. 2400.14...

2009-07-01

211

76 FR 43957 - Modifications of Certain Derivative Contracts  

Federal Register 2010, 2011, 2012, 2013

...1545-BK13 Modifications of Certain Derivative Contracts AGENCY: Internal Revenue...when there is an assignment of certain derivative contracts. The text of those regulations...that the transfer or assignment of a derivative contract in certain situations is...

2011-07-22

212

76 FR 43892 - Modifications of Certain Derivative Contracts  

Federal Register 2010, 2011, 2012, 2013

...1545-BK14 Modifications of Certain Derivative Contracts AGENCY: Internal Revenue...a transfer or assignment of certain derivative contracts does not result in an exchange...necessitate the movement of entire books of derivative contracts. In particular, there...

2011-07-22

213

21 CFR 173.135 - Catalase derived from Micrococcus lysodeikticus.  

Code of Federal Regulations, 2010 CFR

...2012-04-01 2012-04-01 false Catalase derived from Micrococcus lysodeikticus...Preparations and Microorganisms § 173.135 Catalase derived from Micrococcus lysodeikticus. Bacterial catalase derived from Micrococcus...

2012-04-01

214

Method of Introducing Hydroxyl Groups into Artemisinin and Its Derivatives.  

National Technical Information Service (NTIS)

The fungus Beauveria sulfurescens has been employed to introduce hydroxyl groups into artemisinin and derivatives of artemisinin, an antimalarial. Hydroxylated derivatives of artemisinin and derivatives of artemisinin produced thereby possess antimalarial...

H. Ziffer Y. Hu

1991-01-01

215

40 CFR 721.10172 - Alkylamide derivative (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Alkylamide derivative (generic). 721.10172...Chemical Substances § 721.10172 Alkylamide derivative (generic). (a) Chemical...chemical substance identified generically as alkylamide derivative (PMN P-03-633)...

2010-07-01

216

21 CFR 173.135 - Catalase derived from Micrococcus lysodeikticus.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Catalase derived from Micrococcus lysodeikticus. 173.135 Section... § 173.135 Catalase derived from Micrococcus lysodeikticus. Bacterial catalase derived from Micrococcus lysodeikticus by a pure...

2009-04-01

217

21 CFR 173.135 - Catalase derived from Micrococcus lysodeikticus.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 true Catalase derived from Micrococcus lysodeikticus. 173.135 Section... § 173.135 Catalase derived from Micrococcus lysodeikticus. Bacterial catalase derived from Micrococcus lysodeikticus by a pure...

2010-01-01

218

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Substituted phenylimino carbamate derivative. 721.2025 Section 721...721.2025 Substituted phenylimino carbamate derivative. (a) Chemical substance...generically as a substituted phenylimino carbamate derivative (PMN P-91-487)...

2010-07-01

219

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Substituted phenylimino carbamate derivative. 721.2025 Section 721...721.2025 Substituted phenylimino carbamate derivative. (a) Chemical substance...generically as a substituted phenylimino carbamate derivative (PMN P-91-487)...

2013-07-01

220

40 CFR 721.2025 - Substituted phenylimino carbamate derivative.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Substituted phenylimino carbamate derivative. 721.2025 Section 721...721.2025 Substituted phenylimino carbamate derivative. (a) Chemical substance...generically as a substituted phenylimino carbamate derivative (PMN P-91-487)...

2009-07-01

221

40 CFR 721.6097 - Phosphoric acid derivative (generic name).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Phosphoric acid derivative (generic name...Chemical Substances § 721.6097 Phosphoric acid derivative (generic name...substance identified generically as a phosphoric acid derivative (PMN...

2010-07-01

222

Study on resist performance of chemically amplified molecular resist based on noria derivative and calixarene derivative  

NASA Astrophysics Data System (ADS)

Novel resist materials are required for lithographic processing with ionization radiation such as extreme ultraviolet (EUV) and electron beam (EB) exposure tool. In this study, we developed positive-tone chemically amplified molecular resists based on noria derivatives and calixarene derivatives and evaluated the lithographic performance using EUV and EB. We make clear that a small change in modification of noria resists can cause a significant change of sensitivity. Especially, it is useful for the improvement of resist sensitivities to use protecting groups such as 2-acetyloxy-2-methyladamantyl ester (AD) groups and ethoxy groups. Also, novel calixarene derivative such as pillar[5]arene protected by AD showed a semi-isolated pattern with the line width of 40 nm (pitch: 100nm). Noria derivatives and calixarene derivative resists were promising candidates because of high sensitivity, high resolution and etch durability similar to conventional resist such as ZEP 520A and UVIII.

Yamamoto, Hiroki; Kudo, Hiroto; Kozawa, Takahiro

2014-03-01

223

Mathematical Relationships Derived from Biodiesel Fuels  

Microsoft Academic Search

The objective of this study was to estimate mathematical relationships derived from biodiesel fuels from various vegetable oils by non-catalytic supercritical methanol and ethanol method. The vegetable oils are all extremely viscous with viscosities ranging from 10 to 20 times greater than petroleum diesel fuel. The aim of the transesterification process is to lower the viscosity of the oil. Methyl

A. Demirbas

2007-01-01

224

ES cell-derived neuroepithelial cell cultures.  

PubMed

ES cells have the potential to differentiate into cells from all germ layers, which makes them an attractive tool for the development of new therapies. In general, the differentiation of ES cells follows the concept to first generate immature progenitor cells, which then can be propagated and differentiated into mature cellular phenotypes. This also applies for ES cell-derived neurogenesis, in which the development of neural cells follows two major steps: First, the derivation and expansion of immature neuroepithelial precursors and second, their differentiation into mature neural cells. A common method to produce neural progenitors from ES cells is based on embryoid body (EB) formation, which reveals the differentiation of cells from all germ layers including neuroectoderm. An alternative and more efficient method to induce neuroepithelial cell development uses stromal cell-derived inducing activity (SDIA), which can be achieved by co-culturing ES cells with skull bone marrow-derived stromal cells. Both, EB formation and SDIA, reveal the development of rosette-like structures, which are thought to resemble neural tube- and/or neural crest-like progenitors. The neural precursors can be isolated, expanded and further differentiated into specific neurons and glia cells using defined culture conditions. Here, we describe the generation and isolation of such rosettes in co-culture experiments with the stromal cell line MS5 (2-5). PMID:18704173

Karki, Shreeya; Pruszak, Jan; Isacson, Ole; Sonntag, Kai C

2006-12-01

225

Dielectric spectra of natural cork and derivatives  

Microsoft Academic Search

Cork is a cellular biomaterial that has unique characteristics that make it suitable for many types of applications. Since it is also an electrical insulator, the study of its electrical and dielectric properties can lead to new interesting applications. The moisture present in cork and derivatives has a very important role on the dielectric properties. In this work a composite

M. C. Lança; M. Brandt; E. R. Neagu; C. J. Dias; J. N. Marat-Mendes

2010-01-01

226

Deriving a Pedagogy of Educational Foundations  

ERIC Educational Resources Information Center

This sixth and last paper in the series describes four elements believed to be crucial to a high quality pedagogy for educational foundations. These four elements are derived from a close reading of the previous papers. The work of Osguthorpe, Sanger, Haniford, and Mucher, four of the authors in this series, is cited as both a source for these…

Fenstermacher, Gary D.

2007-01-01

227

Simple Derivation of the Lindblad Equation  

ERIC Educational Resources Information Center

The Lindblad equation is an evolution equation for the density matrix in quantum theory. It is the general linear, Markovian, form which ensures that the density matrix is Hermitian, trace 1, positive and completely positive. Some elementary examples of the Lindblad equation are given. The derivation of the Lindblad equation presented here is…

Pearle, Philip

2012-01-01

228

Potentials of Arbitrary Forces with Fractional Derivatives  

NASA Astrophysics Data System (ADS)

The Laplace transform of fractional integrals and fractional derivatives is used to develop a general formula for determining the potentials of arbitrary forces: conservative and nonconservative in order to introduce dissipative effects (such as friction) into Lagrangian and Hamiltonian mechanics. The results are found to be in exact agreement with Riewe's results of special cases. Illustrative examples are given.

Rabei, Eqab M.; Alhalholy, Tareq S.; Rousan, Akram

229

Biotransformation of indole derivatives by mycelial cultures.  

PubMed

Biotransformation of tryptophan to tryptamine and 3-methyl-indole by Psilocybe coprophila was performed. On the other hand, Aspergillus niger was able to transform tryptophan to 5-hydroxy-tryptophan. P. coprophila biotransformed 5-hydroxy-tryptophan to 5-hydroxytryptamine. These results prove once more that fungi are good tools to establish hydroxyindole derivatives. PMID:18386493

Alarcón, Julio; Cid, Eliseo; Lillo, Luis; Céspedesa, Carlos; Aguila, Sergio; Alderete, Joel B

2008-01-01

230

High Resolution Sea Surface Temperature Field Derived.  

National Technical Information Service (NTIS)

A procedure for deriving high resolution sea surface temperature field from digital AVHRR/HRPT data is described. For the purpose of reducing the processing time, only the reflective threshold or near infrared channel is used for selecting data over clear...

S. Zhou W. Chen L. Zhang

1986-01-01

231

Waste-Wood-Derived Fillers for Plastics  

Microsoft Academic Search

Abstract Filled thermoplastic composites are stiffer, stronger, and more dimensionally stable than their unfilled counterparts Such thermoplastics are usually provided to the end - user as a precompounded, pelletized feedstock Typical reinforcing fillers are inorganic materials like talc or fiberglass, but materials derived from waste wood, such as wood flour and recycled paper fiber, are also effective as fillers The

Brent English; Craig M. Clemons; Nicole Stark; James P. Schneider

232

Pyrolysis kinetics of refuse-derived fuel  

Microsoft Academic Search

Refuse-derived fuel (RDF) was mechanically separated from municipal solid waste (MSW) in a 300 TPD (tons per day) waste pretreatment plant. Pyrolysis of the RDF produced approximately 28% of oils, and 30% of noncondensible hydrocarbon gases and 42% of solid residues at 773 K. Thermal gravimetric analysis (TGA) techniques were used in quantitative prediction of the RDF pyrolysis rate. The

Kuen-Song Lin; H. Paul Wang; S.-H Liu; Ni-Bin Chang; Y.-J Huang; H.-C Wang

1999-01-01

233

Synthesis of Sterically Rigid Cystamine Derivatives.  

National Technical Information Service (NTIS)

The possibility exists that the cystamine class of radiation protection drugs may be active only in certain conformations. If this should prove to be the case then cystamine derivatives that are rigidly held in the required conformation may be much more e...

R. M. Wilson D. N. Buchanan

1974-01-01

234

Synthesis of Sterically Rigid Cystamine Derivatives.  

National Technical Information Service (NTIS)

The possibility exists that the cystamine class of radiation protection drugs may be active only in certain conformations. If this should prove to be the cse then cystamine derivatives that are rigidly held in the required conformation may be much more ef...

D. N. Buchanan R. M. Wilson

1971-01-01

235

Antitumor activity of methylan polysaccharide derivatives.  

PubMed

Methylan polysaccharide derivatives were prepared by dialkylaminoalkylation and reductive amination followed by quaternization. Their antitumor activity was investigated and a relationship between structure and activity is suggested. For quaternized DEAE-methylan at only 75 mug ml(-1), tumor cell proliferation was suppressed by 58-84% in three cell lines tested in the order Colo < Hela < HepG2. PMID:20349111

Ramachandran, Priyadharshini; Jeya, Marimuthu; Moon, Hee-Jung; Lee, Kyoung-Mi; Kim, In-Won; Kim, Jung-Hoe; Lee, Jung-Kul

2010-07-01

236

Attenuation Correction In PET By Derived Projections  

Microsoft Academic Search

An improved approach to the attenuation correction necessary to produce quantitatively significant images with PET is presented. The algorithm retains the prac- tical properties of a measured attenuation conection, but reduces the variance in common applications. The basis of this technique is to reconstruct the attenua- tion image from the measured projections and then derive prs- jections from this image

D. C. Ficke; D. E. Beecher; G. R. Hoffman; M. M. Ter-Pogossian

1990-01-01

237

Intelligent Use of Model-Derived Products  

NSDL National Science Digital Library

Many NWP output products must undergo internal processing in order to be readily displayed and used. This module examines how such products are developed, their strengths and weaknesses, and their application in the forecast process. The module focuses on three primary groups of model-derived products: postprocessed products, statistical guidance products, and model assessment tools.

Spangler, Tim

1999-08-31

238

High speed point derivative microseismic detector  

DOEpatents

A high speed microseismic event detector constructed in accordance with the present invention uses a point derivative comb to quickly and accurately detect microseismic events. Compressional and shear waves impinging upon microseismic receiver stations disposed to collect waves are converted into digital data and analyzed using a point derivative comb including assurance of quiet periods prior to declaration of microseismic events. If a sufficient number of quiet periods have passed, the square of a two point derivative of the incoming digital signal is compared to a trip level threshold exceeding the determined noise level to declare a valid trial event. The squaring of the derivative emphasizes the differences between noise and signal, and the valid event is preferably declared when the trip threshold has been exceeded over a temporal comb width to realize a comb over a given time period. Once a trial event has been declared, the event is verified through a spatial comb, which applies the temporal event comb to additional stations. The detector according to the present invention quickly and accurately detects initial compressional waves indicative of a microseismic event which typically exceed the ambient cultural noise level by a small amount, and distinguishes the waves from subsequent larger amplitude shear waves. 9 figs.

Uhl, J.E.; Warpinski, N.R.; Whetten, E.B.

1998-06-30

239

Robust Derivation of Risk Reduction Strategies  

NASA Technical Reports Server (NTRS)

Effective risk reduction strategies can be derived mechanically given sufficient characterization of the risks present in the system and the effectiveness of available risk reduction techniques. In this paper, we address an important question: can we reliably expect mechanically derived risk reduction strategies to be better than fixed or hand-selected risk reduction strategies, given that the quantitative assessment of risks and risk reduction techniques upon which mechanical derivation is based is difficult and likely to be inaccurate? We consider this question relative to two methods for deriving effective risk reduction strategies: the strategic method defined by Kazman, Port et al [Port et al, 2005], and the Defect Detection and Prevention (DDP) tool [Feather & Cornford, 2003]. We performed a number of sensitivity experiments to evaluate how inaccurate knowledge of risk and risk reduction techniques affect the performance of the strategies computed by the Strategic Method compared to a variety of alternative strategies. The experimental results indicate that strategies computed by the Strategic Method were significantly more effective than the alternative risk reduction strategies, even when knowledge of risk and risk reduction techniques was very inaccurate. The robustness of the Strategic Method suggests that its use should be considered in a wide range of projects.

Richardson, Julian; Port, Daniel; Feather, Martin

2007-01-01

240

Sol-Gel Derived Hafnia Coatings  

NASA Technical Reports Server (NTRS)

Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.

Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

2002-01-01

241

78 FR 76787 - Position Limits for Derivatives  

Federal Register 2010, 2011, 2012, 2013

...37, 38, 140 and 150 RIN 3038-AD99 Position Limits for Derivatives Correction In proposed rule document 2013-27200 appearing...100 3,100 .............. CME Feeder Cattle (FC).. 2011 44,611 43,730 3,000 3,000 3,000 2012...

2013-12-19

242

Derivation of the Ideal Gas Law  

ERIC Educational Resources Information Center

Undergraduate and graduate physics and chemistry books usually state that combining the gas laws results in the ideal gas law. Leaving the derivation to the students implies that this should be a simple task, most likely a substitution. Boyle's law, Charles's law, and the Avogadro's principle are given under certain conditions; therefore, direct…

Laugier, Alexander; Garai, Jozsef

2007-01-01

243

Optical limiting properties of [60]fullerene derivatives  

SciTech Connect

Materials such as organic dyes that are strong nonlinear absorbers are being investigated as optical limiting materials for potential applications in the protection of sensors and human eyes from laser radiations. The optical limiting properties of methano[60]fullerene and pyrrolidino[60]fullerene derivatives were investigated. 27 refs., 8 figs., 1 tab.

Sun, Ya-Ping; Riggs, J.E.; Liu, Bing [Clemson Univ., SC (United States)] [Clemson Univ., SC (United States)

1997-05-01

244

Techniques for automatic video content derivation  

Microsoft Academic Search

In this paper, we focus on the use of three different techniques that support automatic derivation of video content from raw video data, namely, a spatio-temporal rule-based method, hidden Markov models, and dynamic Bayesian networks. These techniques are validated in the particular domain of tennis and Formula 1 race videos. We present the experimental results for the detection of events

Milan Petkovic; Vojkan Mihajlovic; Willem Jonker

2003-01-01

245

Convenient syntheses of isomaltose derivatives from amygdalin  

Microsoft Academic Search

The isomaltose trichloroacetimidate 7 was synthesized in five steps from d-amygdalin. The key step in this series of reactions was the acid catalyzed rearrangement of the inter-glycosydic bond to give the thermodynamically more stable ?-anomer. The reaction was also applied to different di-, tri-, and tetrasaccharide derivatives of amygdalin giving the corresponding rearrangement products.

Martin Chwalek; Karen Plé

2004-01-01

246

Inhibition of topoisomerase I by naphthoquinone derivatives  

Microsoft Academic Search

Alkannin and shikonin are naturally occurring naphthoquinones. We have tested several derivatives of the title compounds and we have found that naphthoquinones bearing at least one phenolic hydroxyl group are potent inhibitors of topoisomerase I. The ability of the tested compounds to complex Zn++ parallels with a few exceptions their topoisomerase I inhibition properties while their intercalation and redox properties

Zoi F. Plyta; Tianhu Li; Vassilios P. Papageorgiou; Antonios S. Mellidis; Andreana N. Assimopoulou; Emmanuel N. Pitsinos; Elias A. Couladouros

1998-01-01

247

Financial Derivatives Market for Grid Computing  

Microsoft Academic Search

This Master thesis studies the feasibility and properties of a financial derivatives market on Grid computing, a service for sharing computing resources over a network such as the Internet. For the European Organization for Nuclear Research (CERN) to perform research with the world's largest and most complex machine, the Large Hadron Collider (LHC), Grid computing was developed to handle the

David Aubert; Arnstein Seljeflot Solli; Snorre Lindset; Henning Huuse

2007-01-01

248

An Overview of the Literature about Derivatives  

Microsoft Academic Search

A derivative is defined by the BIS (1995) as “a contract whose value depends on the price of underlying assets, but which does not require any investment of principal in those assets. As a contract between two counterparts to exchange payments based on underlying prices or yields, any transfer of ownership of the underlying asset and cash flows becomes unnecessary”.

Chiara Oldani

2005-01-01

249

Approximate methods for derivation of covariance data  

SciTech Connect

Several approaches for the derivation of covariance information for evaluated nuclear data files (EFF2 and ENDF/B-VI) have been developed and used at IRK and ORNL respectively. Considerations, governing the choice of a distinct method depending on the quantity and quality of available data are presented, advantages/disadvantages are discussed and examples of results are given.

Tagesen, S. [Vienna Univ. (Austria). Inst. fuer Radiumforschung und Kernphysik; Larson, D.C. [Oak Ridge National Lab., TN (United States)

1992-12-31

250

Embryogenesis in callus derived from rice microspores  

Microsoft Academic Search

Differentiating calli derived from rice (Oryza sativa L.) microspores were examined histologically. Shoot and root meristems were observed to be arising by both organogenesis as well as embryogenesis. Embryoid attachment to callus (as well as other embryoids) was at the scutellum adjacent to the mesocotyl and radicle. These observations could be interpreted as an indication of the totipotent plasticity of

A. D. Genovesi; C. W. Magill

1982-01-01

251

Tormentic acid derivatives: synthesis and apoptotic activity.  

PubMed

Several derivatives of tormentic acid have been prepared and tested for their antitumor activity. The dichloroacetate 14 is an excellent antitumor active agent acting by an apoptose inducing pathway as demonstrated by OA/PI staining, DNA laddering experiments as well as by an annexin V binding assay. PMID:22995818

Csuk, René; Siewert, Bianka; Dressel, Christian; Schäfer, Renate

2012-10-01

252

Combustion Studies of Coal Derived Fuels.  

National Technical Information Service (NTIS)

Combustion studies were conducted to evaluate the suitability of using a coal-derived aviation fuel as a candidate JP-900 i.e. a aviation fuel having maximum temperature capability of 482C (900F). Specific progress made for the four tasks constituting Del...

R. J. Santoro

2000-01-01

253

UNDERSTANDING, DERIVING, AND COMPUTING BUFFER CAPACITY  

EPA Science Inventory

Derivation and systematic calculation of buffer capacity is a topic that seems often to be neglected in chemistry courses and given minimal treatment in most texts. However, buffer capacity is very important in the chemistry of natural waters and potable water. It affects corro...

254

High speed point derivative microseismic detector  

DOEpatents

A high speed microseismic event detector constructed in accordance with the present invention uses a point derivative comb to quickly and accurately detect microseismic events. Compressional and shear waves impinging upon microseismic receiver stations disposed to collect waves are converted into digital data and analyzed using a point derivative comb including assurance of quiet periods prior to declaration of microseismic events. If a sufficient number of quiet periods have passed, the square of a two point derivative of the incoming digital signal is compared to a trip level threshold exceeding the determined noise level to declare a valid trial event. The squaring of the derivative emphasizes the differences between noise and signal, and the valid event is preferably declared when the trip threshold has been exceeded over a temporal comb width to realize a comb over a given time period. Once a trial event has been declared, the event is verified through a spatial comb, which applies the temporal event comb to additional stations. The detector according to the present invention quickly and accurately detects initial compressional waves indicative of a microseismic event which typically exceed the ambient cultural noise level by a small amount, and distinguishes the waves from subsequent larger amplitude shear waves.

Uhl, James Eugene (Albuquerque, NM); Warpinski, Norman Raymond (Albuquerque, NM); Whetten, Ernest Blayne (Albuquerque, NM)

1998-01-01

255

Improved Design of Proportional Integral Derivative Charts  

Microsoft Academic Search

Jiang et al. (2002) introduced proportional integral derivative (PID) control charts for monitoring au- tocorrelated processes based on PID predictors and corresponding residuals. The major contribution of the PID chart is to bridge between engineering process control (EPC) techniques and statistical process control (SPC) schemes. Although the performance of PID charts has been reported in the literature, we focus on

FUGEE TSUNG; YI ZHAO; LIMING XIANG; WEI JIANG

2006-01-01

256

Method of Obtaining S-Triazine Derivatives.  

National Technical Information Service (NTIS)

A method of obtaining derivatives of S-triazines as found in 2-((R-chloro-)triazin-2-yl)amino)butyronitrile where R is the alkylamino-, dialkylamino-, or the 2-((2-nitrilo)propyl)amino group is distinguished by the fact that cyanuric chloride is subjected...

F. V. Avetisyan V. V. Dovlatyan

1972-01-01

257

The Solubility of Some Azafullerene Derivatives  

Microsoft Academic Search

Several fulleroaziridines, azafulleroids and chiral cage-opened ketolactams were synthesized from alkyl azides and C60. Their solubility in various solvents was evaluated by HPLC. It depends both on the starting azide and the linker group. Moreover, the formation of two sp carbons (entries 2) and then of carbonyl derivatives (entries 3) induces a decrease of the polarizability of the C60 moiety

G. Le Strat; N. Noiret; A. Roucoux; H. Patin

1999-01-01

258

Ecosystem Services Derived from Headwater Catchments  

EPA Science Inventory

We used data from the USEPA?s wadeable streams assessment (WSA), US Forest Service?s forest inventory and analysis (FIA), and select USFS experimental forests (EF) to investigate potential ecosystems services derived from headwater catchments. C, N, and P inputs to these catchmen...

259

On Deriving CED Effects from the PIC  

Microsoft Academic Search

This article shows that a version of the Condition on Extraction Domain (Huang 1982) can be derived from the Phase Impenetrability Condition (PIC; Chomsky 2001, 2008) if the following assumptions are made: (a) All syntactic operations are driven by features of lexical items. (b) These features are ordered on lexical items. (c) All phrases are phases. (d) Edge features that

Gereon Müller

2010-01-01

260

Radon-Nikodym Derivatives of Gaussian Measures  

Microsoft Academic Search

We give simple necessary and sufficient conditions on the mean and covariance for a Gaussian measure to be equivalent to Wiener measure. This was formerly an unsolved problem [26]. An unsolved problem is to obtain the Radom-Nikodym derivative $d\\\\mu\\/d\\\

L. A. Shepp

1966-01-01

261

New norbornyl derivatives as woody fragrant materials.  

PubMed

The optimization of a Diels-Alder reaction to prepare a novel ketone bearing a 2,3-dimethylnorbornyl group is presented together with the structure elucidation of the isomers. Employing this new ketone as starting material, derivatives with new woody odor notes as well as attempts to obtain ambery-musky odorants are reported. PMID:18618398

Muratore, Agnès; Duñach, Elisabet; Clinet, Jean-Claude; Plessis, Caroline

2008-06-01

262

Derivatives and the Graphs of Functions Microworld  

NSDL National Science Digital Library

The purpose of this Microworld is to experiment with some of the general applications of the derivative to the study of the behavior of functions. This includes their critical behavior, their local extrema, regions of monotonicity (increasing or decreasing), and their inflection points.

White, James

2004-11-01

263

Metal-carboxylic Acids and Their Derivatives  

NASA Astrophysics Data System (ADS)

Questions connected with the synthesis of metal-carboxylic acids, compounds incorporating [M]-COOH fragments with a metal-carbon bond in which M is a transition metal complex, and their derivatives (salts, esters, and amides) are considered. The bibliography includes 189 references.

Kolomnikov, I. S.; Lysyak, T. V.; Rusakov, S. L.; Kharitonov, Yu Ya

1988-05-01

264

Tectonic plate motions derived from Lageos  

Microsoft Academic Search

Five years of laser data (1984-88) between the Lageos satellite and the ground station network based on precise monthly computations of the Lageos satellite are analyzed to recover tectonic motions affecting the stations. A global inversion over this period provides solutions for absolute velocities in latitude and longitude of a selected subset of 14 stations. Relative horizontal velocities are derived

R. Biancale; A. Cazenave; K. Dominh

1991-01-01

265

Bacterial degradation of chlorophenols and their derivatives.  

PubMed

Chlorophenols (CPs) and their derivatives are persistent environmental pollutants which are used in the manufacture of dyes, drugs, pesticides and other industrial products. CPs, which include monochlorophenols, polychlorophenols, chloronitrophenols, chloroaminophenols and chloromethylphenols, are highly toxic to living beings due to their carcinogenic, mutagenic and cytotoxic properties. Several physico-chemical and biological methods have been used for removal of CPs from the environment. Bacterial degradation has been considered a cost-effective and eco-friendly method of removing CPs from the environment. Several bacteria that use CPs as their sole carbon and energy sources have been isolated and characterized. Additionally, the metabolic pathways for degradation of CPs have been studied in bacteria and the genes and enzymes involved in the degradation of various CPs have been identified and characterized. This review describes the biochemical and genetic basis of the degradation of CPs and their derivatives. PMID:24589366

Arora, Pankaj Kumar; Bae, Hanhong

2014-01-01

266

Mantle-derived Archaean monzodiorites and trachyandesites  

NASA Technical Reports Server (NTRS)

Geochemical data on monzodiorites and trachyandesites from the Rainy Lake area in Ontario which are strongly enriched in large-ion lithophile elements (LILE) are presented. It is concluded that they are derived by direct melting of the mantle at depths of less than 50 km in either anhydrous or hydrous conditions. Their rare earth element abundances and initial Nd-143/Nd-144 ratios suggest that their mantle sources were enriched in LILE shortly before melting. The monzodiorites-trachyandesites and their granodioritic derivatives may comprise up to 20 percent of the exposed igneous rocks in the Rainy Lake region and Vermilion District. If these rocks are as abundant in other Archaean terranes, a significant part of the early continental crust could have formed by direct melting of LILE-enriched mantle.

Shirey, S. B.; Hanson, G. N.

1984-01-01

267

Hydrocarbon and nonhydrocarbon derivatives of cyclopropane  

NASA Technical Reports Server (NTRS)

The methods used to prepare and purify 19 hydrocarbon derivatives of cyclopropane are discussed. Of these hydrocarbons, 13 were synthesized for the first time. In addition to the hydrocarbons, six cyclopropylcarbinols, five alkyl cyclopropyl ketones, three cyclopropyl chlorides, and one cyclopropanedicarboxylate were prepared as synthesis intermediates. The melting points, boiling points, refractive indices, densities, and, in some instances, heats of combustion of both the hydrocarbon and nonhydrocarbon derivatives of cyclopropane were determined. These data and the infrared spectrum of each of the 34 cyclopropane compounds are presented in this report. The infrared absorption bands characteristic of the cyclopropyl ring are discussed, and some observations are made on the contribution of the cyclopropyl ring to the molecular refractions of cyclopropane compounds.

Slabey, Vernon A; Wise, Paul H; Gibbons, Louis C

1953-01-01

268

Synthesis and biological evaluation of formazan derivatives  

PubMed Central

The formazan derivatives (FM1–FM5) were synthesized by the reaction of benzaldehyde phenylhydrazone with substituted aromatic and hetero aromatic amines. The structures of the synthesized compounds were then elucidated using UV, IR, 1H NMR and mass spectral data. The synthesized derivatives were screened for anticonvulsant, antibacterial and antiviral activities. All the compounds showed remarkable antibacterial activity at 250 ?g/ml, but FM4 and FM3 did not show any inhibition on Staphylococcus aureus and Vibriocholera, respectively. All the compounds showed significant anticonvulsant effect at 100 mg/kg p.o. and the experimental data were statistically significant at P<0.001 level. But none of the compounds was effective against Japanese encephalitis virus.

Mariappan, Gurusamy; Korim, Rejaul; Joshi, Nand Madhwa; Alam, Faruk; Hazarika, Rajib; Kumar, Deepak; Uriah, Tiewlasubon

2010-01-01

269

Tooth-derived bone graft material  

PubMed Central

With successful extraction of growth factors and bone morphogenic proteins (BMPs) from mammalian teeth, many researchers have supported development of a bone substitute using tooth-derived substances. Some studies have also expanded the potential use of teeth as a carrier for growth factors and stem cells. A broad overview of the published findings with regard to tooth-derived regenerative tissue engineering technique is outlined. Considering more than 100 published papers, our team has developed the protocols and techniques for processing of bone graft material using extracted teeth. Based on current studies and studies that will be needed in the future, we can anticipate development of scaffolds, homogenous and xenogenous tooth bone grafts, and dental restorative materials using extracted teeth.

Kim, Young-Kyun; Lee, Junho; Kim, Kyung-Wook; Murata, Masaru; Akazawa, Toshiyuki; Mitsugi, Masaharu

2013-01-01

270

Endogenous Matrix-Derived Inhibitors of Angiogenesis  

PubMed Central

Endogenous inhibitors of angiogenesis are proteins or fragments of proteins that are formed in the body, which can inhibit the angiogenic process. These molecules can be found both in the circulation and sequestered in the extracellular matrix (ECM) surrounding cells. Many matrix-derived inhibitors of angiogenesis, such as endostatin, tumstatin, canstatin and arresten, are bioactive fragments of larger ECM molecules. These substances become released upon proteolysis of the ECM and the vascular basement membrane (VBM) by enzymes of the tumor microenvironment. Although the role of matrix-derived angiogenesis inhibitors is well studied in animal models of cancer, their role in human cancers is less established. In this review we discuss the current knowledge about these molecules and their potential use as cancer therapeutics and biomarkers.

Sund, Malin; Nyberg, Pia; Eikesdal, Hans Petter

2010-01-01

271

Interaction of pyridine derivatives with sepiolite.  

PubMed

In this study, the adsorption behavior of pyridine derivatives, i.e., 2-aminopyridine and 2,2'-bipyridyl, onto sepiolite, a natural clay mineral, has been investigated by bottle adsorption and IR spectroscopic techniques. The results indicate that 2-aminopyridine and 2,2'-bipyridyl molecules adsorb onto sepiolite through hydrogen bonding of the amino groups to the water molecules in the octahedral sheet and to the surface hydroxyls (Si-OH) in the tetrahedral sheet. These findings reveal that pyridine molecules not only adsorb onto the external surface of sepiolite but are also incorporated in its channels and tunnels with adsorption taking place at corners and/or edges, depending on the position of water molecules. A structural model is proposed to account for the orientation of pyridine derivatives in the sepiolite matrix. PMID:16290699

Sabah, E; Celik, M S

2002-07-01

272

Cytotoxic Activities of New Jadomycin Derivatives  

PubMed Central

Cytotoxic activities of jadomycin B and five new jadomycin derivatives against four cancer cell lines (HepG2, IM-9, IM-9/Bcl-2 and H460) were evaluated. Jadomycin S was most potent against HepG2, IM-9 and IM-9/Bcl-2 while jadomycin F was most potent against H460. Their potencies correlated with the degrees of apoptosis induced. Structure-activity-relationship analyses clearly demonstrate that the side chains of the oxazolone ring derived from the incorporated amino acids make a significant impact on biological activity. Therefore, jadomycin offers an ideal scaffold to manipulate structure and could be exploited to make many novel bioactive compounds with altered activities.

Zheng, Jian-Ting; Rix, Uwe; Zhao, Lixia; Mattingly, Cynthia; Adams, Val

2010-01-01

273

Derived Patterns in Binocular Rivalry Networks  

PubMed Central

Binocular rivalry is the alternation in visual perception that can occur when the two eyes are presented with different images. Wilson proposed a class of neuronal network models that generalize rivalry to multiple competing patterns. The networks are assumed to have learned several patterns, and rivalry is identified with time periodic states that have periods of dominance of different patterns. Here, we show that these networks can also support patterns that were not learned, which we call derived. This is important because there is evidence for perception of derived patterns in the binocular rivalry experiments of Kovács, Papathomas, Yang, and Fehér. We construct modified Wilson networks for these experiments and use symmetry breaking to make predictions regarding states that a subject might perceive. Specifically, we modify the networks to include lateral coupling, which is inspired by the known structure of the primary visual cortex. The modified network models make expected the surprising outcomes observed in these experiments.

2013-01-01

274

A new chromone derivative from Berchemia lineata.  

PubMed

To study the chemical constituents from the root of Berchemia lineata (L.) DC., nine compounds were isolated from the EtOAc extract by using silica gel, RP-C18 silica gel column chromatography and preparative HPLC. Based on the spectroscopic analysis, their structures were identified as 5-hydroxy-7-(2'-hydroxypropyl)-2-methyl-chromone (1), (-)-(1'R, 2'S)-erythro-5-hydroxy-7-(1', 2'-dihydroxypropyl)-2-methyl-chromone (2), naringenin (3), eriodictyol (4), (+)-aromadendrin (5), (+)-taxifolin (6), (+)-catechin (7), (+)-epigallocatechin (8) and quercetin (9). Among them, compound 2 is a new chromone derivative. Compound 1 is a known chromone derivative and isolated from this genus for the first time. Compounds 3-9 are known flavonoids and isolated from this plant for the first time. PMID:21348425

Shen, Yu-xia; Teng, Hong-li; Yang, Guang-zhong; Mei, Zhi-nan; Chen, Xiao-long

2010-09-01

275

Multifocus moveout revisited: derivations and alternative expressions  

NASA Astrophysics Data System (ADS)

The multifocus moveout of Gelchinsky et al. [Gelchinsky, B., Berkovitch, A., Keydar, S., 1997. Multifocusing homeomorphic imaging: Parts I and II: Course Notes, Special Course on Homeomorphic Imaging. Seeheim, Germany] is a powerful tool for stacking multicoverage data in arbitrary configurations. Based on general ray theoretical assumptions and on attractively simple geometrical considerations, the multifocus moveout is designed to express the traveltimes of neighbouring rays arbitrarily located around a fixed central, primary reflected or even diffracted, ray. In this work, the basic derivations and results concerning the multifocus approach are reviewed. A higher-order multifocus moveout expression that generalizes the corresponding one of Gelchinsky is obtained from slight modifications of the original derivation. An alternative form of the obtained multifocus expression that is best suited for numerical implementation is also provided. By means of a simple numerical experiment, we also comment on the accuracy of the multifocus traveltime approximations.

Tygel, Martin; Santos, Lúcio T.; Schleicher, Jörg

1999-12-01

276

A derivative standard for polarimeter calibration  

SciTech Connect

A long-standing problem in polarized electron physics is the lack of a traceable standard for calibrating electron spin polarimeters. While several polarimeters are absolutely calibrated to better than 2%, the typical instrument has an inherent accuracy no better than 10%. This variability among polarimeters makes it difficult to compare advances in polarized electron sources between laboratories. The authors have undertaken an effort to establish 100 nm thick molecular beam epitaxy grown GaAs(110) as a material which may be used as a derivative standard for calibrating systems possessing a solid state polarized electron source. The near-bandgap spin polarization of photoelectrons emitted from this material has been characterized for a variety of conditions and several laboratories which possess well calibrated polarimeters have measured the photoelectron polarization of cathodes cut from a common wafer. Despite instrumentation differences, the spread in the measurements is sufficiently small that this material may be used as a derivative calibration standard.

Mulhollan, G.; Clendenin, J.; Saez, P. [and others

1996-10-01

277

Canonical equilibrium distribution derived from Helmholtz potential  

NASA Astrophysics Data System (ADS)

Plastino and Curado [A. Plastino, E.M.F. Curado, Phys. Rev. E 72 (2005) 047103] recently determined the equilibrium probability distribution for the canonical ensemble using only phenomenological thermodynamical laws as an alternative to the entropy maximization procedure of Jaynes. In the current paper we present another alternative derivation of the canonical equilibrium probability distribution, which is based on the definition of the Helmholtz free energy (and its being constant at the equilibrium) and the assumption of the uniqueness of the equilibrium probability distribution. Noting that this particular derivation is applicable for all trace-form entropies, we also apply it to the Tsallis entropy, showing that the Tsallis entropy yields genuine inverse power laws.

Oikonomou, Thomas; Baris Bagci, G.; Tirnakli, Ugur

2012-12-01

278

Inequalities for a polynomial and its derivative  

NASA Astrophysics Data System (ADS)

Let , 1[less-than-or-equals, slant][mu][less-than-or-equals, slant]n, be a polynomial of degree n such that p(z)[not equal to]0 in z0, then for 0derivative, Math. Inequal. Appl. 2 (2) (1999) 203-205] proved Equality holds for the polynomial where n is a multiple of [mu]E In this paper, we obtain an improvement of the above inequality by involving some of the coefficients. As an application of our result, we further improve upon a result recently proved by Aziz and Shah [A. Aziz, W.M. Shah, Inequalities for a polynomial and its derivative, Math. Inequal. Appl. 7 (3) (2004) 379-391].

Chanam, Barchand; Dewan, K. K.

2007-12-01

279

Synthesis of ?-carboxyphosphinopeptides derived from norleucine  

Microsoft Academic Search

In the present study, we describe in detail the synthesis of a relatively rare class of phosphorus compounds, ?-carboxyphosphinopeptides.\\u000a We prepared several norleucine-derived ?-carboxyphosphinic pseudopeptides of the general formula Nle-?[PO(OH)]-Gly. These\\u000a compounds could have important applications as transition state-mimicking inhibitors for methionine or leucine aminopeptidases\\u000a or other enzymes. For the preparation of the key ?-carboxyphosphinate protected precursors, we investigated, compared

Jan Pícha; Miloš Bud?šínský; Pavel Fiedler; Miloslav Šanda; Ji?í Jirá?ek

2010-01-01

280

Derivation of a class of training algorithms  

Microsoft Academic Search

A novel derivation is presented of T. Kohonen's topographic mapping training algorithm (Self-Organization and Associative Memory, 1984), based upon an extension of the Linde-Buzo-Gray (LBG) algorithm for vector quantizer design. Thus a vector quantizer is designed by minimizing an L2 reconstruction distortion measure, including an additional contribution from the effect of code noise which corrupts the output of the vector

S. P. Luttrell

1990-01-01

281

Derivatives of Carbohydrates with Carbamide Fragments  

NASA Astrophysics Data System (ADS)

A systematic account is given of the results of experimental studies on the synthesis, structures, and properties of carbohydrate-containing derivatives of urea and its analogues — thiourea, selenourea, and iminourea (guanidine). The possibility of using them in the preparative chemistry of carbohydrates and in certain branches of the national economy is demonstrated. The prospects for the development of the chemistry of sugars with ureido-groups are outlined. The bibliography includes 123 references.

Afanas'ev, V. A.; Dzhamanbaev, Zh A.; Zaikov, Gennadii E.

1982-04-01

282

Fractional derivatives, fractional integrals and electromagnetic theory  

Microsoft Academic Search

Summary form only given. Fractional derivatives\\/integrals are mathematical operators involving differentiation\\/integration to arbitrary noninteger orders-orders that may be fractional or even complex. These operators, which possess interesting mathematical properties, have been studied in the field of fractional calculus. In our study, we have applied the tools of fractional calculus in various problems in electromagnetic fields and waves, and have obtained

Nader Engheta

1999-01-01

283

Biological activity of galactoglucomannan-derived oligosaccharides  

Microsoft Academic Search

A mixture of galactoglucomannan-derived oligosaccharides (GGMOs), degree of polymerization 4–8, (˜1.2 µM and ˜12 µM) stimulated the viability of spruce [Picea abies (L.) Karst] embryos predominately on media supplemented with indole-3-acetic acid: zeatin (0.01:1, 1:0.01 mg · 1-1), at pH 5.O. Their effects on the development and morphogenesis of embryos were dependent on the culture conditions used. These GGMOs also

D. Lišková; O. Auxtová; D. Kákoniová; M. Kuba?ková; Š. Karácsonyi; L. Bilisics

1995-01-01

284

Antiaggregant activity of a new benzimidazole derivative.  

PubMed

Antiaggregant activity of a new tricyclic benzimidazole derivative, RU-891 compound, was studied on the model of ADP-induced platelet aggregation in vitro and intravascular platelet aggregation in vivo. We evaluated the effect of this substance on blood coagulation potential. Antiaggregant agent acetylsalicylic acid was used as the reference drug. RU-891 produced a dose-dependent antiaggregant effect in vivo and in vitro that exceeded the effect of the reference drug. This compound did not modulate blood coagulation potential. PMID:24824700

Kucheryavenko, A F; Spasov, A A; Petrov, V I; Anisimova, V A

2014-04-01

285

[Analgesic properties of morpholinoethylimidazobenzimidazole derivative RU-1205].  

PubMed

We have studied the analgesic activity of a morpholinoethylimidazobenzimidazole derivative (RU-1205) in comparison to butorphanol. It is established that the test compound exhibits a pronounced analgesic activity, which exceeded that ofbutorphanol six times in the hot-plate test and was comparable to the reference drug effect in the tail-flick and acetic acid-induced writhing tests. It is established that the analgesic action of RU-1205 is based on the kappa-opioidergic mechanism. PMID:24432563

Spasov, A A; Grechko, O Iu; Shtareva, D M; Anisimova, V A

2013-01-01

286

Derivative processes for modelling metabolic fluxes  

PubMed Central

Motivation: One of the challenging questions in modelling biological systems is to characterize the functional forms of the processes that control and orchestrate molecular and cellular phenotypes. Recently proposed methods for the analysis of metabolic pathways, for example, dynamic flux estimation, can only provide estimates of the underlying fluxes at discrete time points but fail to capture the complete temporal behaviour. To describe the dynamic variation of the fluxes, we additionally require the assumption of specific functional forms that can capture the temporal behaviour. However, it also remains unclear how to address the noise which might be present in experimentally measured metabolite concentrations. Results: Here we propose a novel approach to modelling metabolic fluxes: derivative processes that are based on multiple-output Gaussian processes (MGPs), which are a flexible non-parametric Bayesian modelling technique. The main advantages that follow from MGPs approach include the natural non-parametric representation of the fluxes and ability to impute the missing data in between the measurements. Our derivative process approach allows us to model changes in metabolite derivative concentrations and to characterize the temporal behaviour of metabolic fluxes from time course data. Because the derivative of a Gaussian process is itself a Gaussian process, we can readily link metabolite concentrations to metabolic fluxes and vice versa. Here we discuss how this can be implemented in an MGP framework and illustrate its application to simple models, including nitrogen metabolism in Escherichia coli. Availability and implementation: R code is available from the authors upon request. Contact: j.norkunaite@imperial.ac.uk; m.stumpf@imperial.ac.uk Supplementary information: Supplementary data are available at Bioinformatics online.

Zurauskiene, Justina; Kirk, Paul; Thorne, Thomas; Pinney, John; Stumpf, Michael

2014-01-01

287

Carbon structures in silicon carbide derived carbon  

Microsoft Academic Search

Carbide derived carbon (CDC) produced by etching SiC in halogens has been investigated using transmission electron microscopy (TEM). Depending on experimental conditions, CDC may contain sp3- or sp2-bonded carbon phases. Amorphous carbon, poorly ordered turbostratic carbon with lattice spacing exceeding values of 0.35nm as well as highly ordered graphite were observed. sp3-Bonded structures consist of mainly lonsdaleite and cubic diamond

Sascha Welz; Michael J. McNallan; Yury Gogotsi

2006-01-01

288

A highly toxic morphine-3-glucuronide derivative.  

PubMed

By the coupling of octylamine to the uronic acid function of morphine-3-glucuronide (M3G) a new glycoconjugate (morphine-3-octylglucuronamide, M3GOAM) was prepared. When assayed in both rats and mice up to ng/kg (i.p.) doses none of the animals survived. The aliphatic octyl chain may be the lethal factor since a closely related derivative (M3GNH2), was not toxic and showed similar opioid antagonist properties than naloxone. PMID:15012991

Salvatella, Mariona; Arsequell, Gemma; Valencia, Gregorio; Rodríguez, Raquel E

2004-02-23

289

Global impact of mutation-derived varieties  

Microsoft Academic Search

During the past seventy years, worldwide more than 2250 varieties have been released that have been derived either as direct\\u000a mutants or from their progenies. Induction of mutations with radiation has been the most frequently used method for directly\\u000a developed mutant varieties. The prime strategy in mutation-based breeding has been to upgrade the well-adapted plant varieties\\u000a by altering one or

B. S. Ahloowalia; M. Maluszynski; K. Nichterlein

2004-01-01

290

Derivation of plutonium-239 materials disposition categories  

SciTech Connect

At this time, the Office of Fissile Materials Disposition within the DOE, is assessing alternatives for the disposition of excess fissile materials. To facilitate the assessment, the Plutonium-Bearing Materials Feed Report for the DOE Fissile Materials Disposition Program Alternatives report was written. The development of the material categories and the derivation of the inventory quantities associated with those categories is documented in this report.

Brough, W.G.

1995-04-27

291

Triamine chelants, their derivatives, complexes and conjugates  

DOEpatents

A group of functionalized triamine chelants and their derivatives that form complexes with radioactive metal ions are disclosed. The complexes can be covalently attached to a protein or an antibody or antibody fragment and used for therapeutic and/or diagnostic purposes. The chelants are of the formula: ##STR1## wherein n, m, R, R.sup.1, R.sup.2 and L are defined in the specification.

Troutner, David E. (Phoenixville, PA); John, Christy S. (Gaithersburg, MD); Pillai, Maroor R. A. (Vashi, IN)

1995-01-01

292

Acetylene-Terminated Aspartimides And Derived Resins  

NASA Technical Reports Server (NTRS)

New polymers and derived blends exhibit improved processability and properties. New toughened epoxies exhibit excellent properties, but use temperatures limited. Bismaleimide resins are some base materials formulated to develop materials having moderate use temperatures. Work conducted on use of acetylenic (ethynyl) group to cross-link and extend chains of oligomers and polymers to obtain materials to perform at higher temperatures. Extended to include acetylene-terminated aspartimides (ATA's).

Hergenrother, Paul M.; Connell, John W.; Havens, Stephen J.

1989-01-01

293

Satellite Derived Tropical Ocean Surface Currents  

NSDL National Science Digital Library

Users can view imagery and read about tropical Pacific near-surface currents. The analysis is based on satellite altimeter- and scatterometer-derived sea level wind data. Materials presented here include monthly surface current maps, beginning with October 1992 and ending with the latest available satellite data (usually about one month delay). Links to related sites, a publications list, and a presentations list are also inlcuded.

294

Nile Blue derivatives as lysosomotropic photosensitizers  

NASA Astrophysics Data System (ADS)

The benzophenoxazines, including several Nile blue analogues, are a unique group of dyes that localize selectively in animal tumors. Chemical modifications of Nile blue A can yield derivatives with high 1O2 quantum yields. These derivatives represent a group of potentially effective photosensitizers for selective phototherapy of malignant tumors. In vitro evaluation of these derivatives has indicated that those with high 1O2 yields are very effective in mediating the photocytotoxicity of tumor cells. This photodynamic effect is most likely mediated through the action of 1O2, since photoirradiation under D2O enhanced and under hypoxic conditions diminished the photocytotoxic action. The subcellular localization of these photosensitizers in bladder tumor cells in culture was examined by light and fluorescence microscopies as well as by histochemical and biochemical studies. The results indicate that these dyes are localized primarily in the lysosome. The cellular uptake and retention of these dyes is energy- and pH-dependent. Agents such as nigericin, which alter the transmembrane pH gradient, reduced uptake and enhanced efflux of the dyes, while agents such as valinomycin, which reduce cellular membrane potential, had no effect on the uptake. These findings are consistent with having ion-trapping as the mechanism for the uptake of these dyes. Photoirradiation of sensitizer-treated cells obliterated lysosomes in a light-dose and drug-dose dependent fashion. Release of the hydrolytic enzymes may be the main cause for subsequent cell death since the cytolytic effect was reduced by a specific inhibitor of lysosomal proteolytic enzyme. A lysosomotropic photosensitization mechanism is therefore proposed for the photocytotoxic action of the Nile blue derivatives. This mechanism may provide an approach to the development of new photosensitizers for the effective and selective destruction of malignant tumors.

Lin, Chi-Wei; Shulok, Janine R.; Kirley, S. D.; Cincotta, Louis; Foley, James W.

1991-06-01

295

Solid waste as refuse-derived fuel  

Microsoft Academic Search

Europe and the Far East have been using refuse-to-energy plants to power turbine generators in the production of electricity. If the U.S. would convert the total municipal refuse to energy at normal efficiency, 6% of the total U.S. electric production could be produced. Pelletized solid waste (refuse-derived fuel (RDF)) can be mixed with coal and burned in existing industrial spreader

R. F. Rolsten; L. Glaspell; J. P. Waltz

1977-01-01

296

Purification of oxyfuel-derived CO 2  

Microsoft Academic Search

Oxyfuel combustion in a pulverised fuel coal-fired power station produces a raw CO2 product containing contaminants such as water vapour plus oxygen, nitrogen and argon derived from the excess oxygen for combustion, impurities in the oxygen used, and any air leakage into the system. There are also acid gases present, such as SO3, SO2, HCl and NOx produced as byproducts

Vince White; Laura Torrente-Murciano; David Sturgeon; David Chadwick

2010-01-01

297

ELECTRONIC PROPERTIES OF TIO 2 DERIVED NANOBELTS  

Microsoft Academic Search

TiO2-based nanostructures are considered good candidates for a number of applications in numerous fields as environmental decontamination, photocatalysis, electrocatalytic storage, solar cells, antibacterial agent, etc (1-3). These applications are based on their electronic properties and high surface area which need to be characterized. Titania derived nanobelts are sensitive to electron beam irradiation requiring to assess the conditions under which the

D. Cadavid; R. F. Egerton; M. Malac; M. S. Moreno

2009-01-01

298

Interaction of Pyridine Derivatives with Sepiolite  

Microsoft Academic Search

In this study, the adsorption behavior of pyridine derivatives, i.e., 2-aminopyridine and 2,2?-bipyridyl, onto sepiolite, a natural clay mineral, has been investigated by bottle adsorption and IR spectroscopic techniques. The results indicate that 2-aminopyridine and 2,2?-bipyridyl molecules adsorb onto sepiolite through hydrogen bonding of the amino groups to the water molecules in the octahedral sheet and to the surface hydroxyls

E. Sabah; M. S. Çelik

2002-01-01

299

Chemically Derived, Ultrasmooth Graphene Nanoribbon Semiconductors  

Microsoft Academic Search

We developed a chemical route to produce graphene nanoribbons (GNR) with width below 10 nanometers, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics. The GNRs were solution-phase derived, stably suspended in solvents with noncovalent polymer functionalization, and exhibited ultrasmooth edges with possibly well-defined zigzag or armchair-edge structures. Electrical

Xiaolin Li; Xinran Wang; Li Zhang; Sangwon Lee; Hongjie Dai

2008-01-01

300

Derivatives of the L p -cosine transform  

Microsoft Academic Search

The Lp-cosine transform of an even, continuous function f?Ce(Sn?1) is defined byH(x)=?Sn?1|?x,??|pf(?)d?,x?Rn.It is shown that if p is not an even integer then all partial derivatives of even order of H(x) up to order p+1 (including p+1 if p is an odd integer) exist and are continuous everywhere in Rn?{0}. As a result of the corresponding differentiation formula, we show

Yossi Lonke

2003-01-01

301

Human marrow-derived mesenchymal progenitor cells  

Microsoft Academic Search

A number of adult mesenchymal tissues contain subpopulations of undifferentiated cells, which retain the capacity to differentiate\\u000a along multiple lineages. These mesenchymal progenitor cells may be cultured in an undifferentiated state and, when given the\\u000a appropriate signals, differentiate into an expanding list of several mesenchymal and a few ectodermal derived tissues. The\\u000a maintenance and propagation of the multipotential nature of

Edward J. Caterson; Leon J. Nesti; Keith G. Danielson; Rocky S. Tuan

2002-01-01

302

Human telomerase inhibition by substituted acridine derivatives  

Microsoft Academic Search

A series of 3,6-disubstituted acridine derivatives have been rationally designed as telomerase inhibitors. They have been designed on the basis that inhibition of telomerase occurs by stabilising G-quadruplex structures formed by the folding of telomeric DNA. The most potent inhibitors have IC50 values against telomerase of between 1.3 and 8 ?M, comparable to their cytotoxicity in ovarian cancer cell lines.

R. John Harrison; Sharon M. Gowan; Lloyd R. Kelland; Stephen Neidle

1999-01-01

303

Bicyclic thiophenic derivatives as platelet aggregation inhibitors.  

PubMed

The antiplatelet activity of twenty new thiophenic derivatives, grouped in three series, was studied according to the in vitro Born method. The DI50 for the three inducers of platelet aggregation ADP, adrenaline and collagen were calculated. The strong antiplatelet activity found in some of the compounds studied, which is even superior to that of the four classic antiplatelet drugs used is worth mentioning. The structure-activity relationships is discussed. PMID:3743742

Darias, V; Bravo, L; Fraile, C; Martin-Herrera, D; Corral, C; Lissavetzky, J

1986-06-01

304

Stilbene derivatives from Gnetum gnemon Linn.  

PubMed

Four stilbene derivatives, gnemonols K and L (resveratrol trimers), M (isorhapontigenin dimer), and gnemonoside K (glucoside of resveratrol trimer) together with eleven known stilbenoids and a lignan were isolated from the acetone, methanol and 70% methanol soluble parts of the root of Gnetum gnemon (Gnetaceae). The structures of the isolates were determined by spectral analysis. The antioxidant activity of the stilbenoids on lipid peroxide inhibition and super oxide scavenging activity were also investigated. PMID:12560033

Iliya, Ibrahim; Ali, Zulfiqar; Tanaka, Toshiyuki; Iinuma, Munekazu; Furusawa, Miyuki; Nakaya, Ken-ichi; Murata, Jin; Darnaedi, Dedy; Matsuura, Nobuyasu; Ubukata, Makoto

2003-02-01

305

Negative K -theory of derived categories  

Microsoft Academic Search

We define negative K-groups for exact categories and for ``derived categories'' in the framework of Frobenius pairs, generalizing definitions\\u000a of Bass, Karoubi, Carter, Pedersen-Weibel and Thomason. We prove localization and vanishing theorems for these groups. Dvissage (for noetherian abelian categories), additivity, and resolution hold. We show that the first negative K-group of an abelian category vanishes, and that, in general,

Marco Schlichting

2006-01-01

306

Synthesis and pharmacological activity of diterpenylnaphthoquinone derivatives.  

PubMed

New diterpenylquinones, combining a diterpene diacid and a naphthoquinone, were prepared from junicedric acid and lapachol. The new derivatives were assessed as gastroprotective agents by the HCl-EtOH-induced gastric lesions model in mice as well as for basal cytotoxicity on the following human cell lines: Normal lung fibroblasts (MRC-5), gastric epithelial adenocarcinoma (AGS), and hepatocellular carcinoma (Hep G2). Several of the new compounds were significantly active as antiulcer agents and showed selective cytotoxicity against AGS cells. PMID:21996716

Pertino, Mariano Walter; Theoduloz, Cristina; Palenzuela, Jose Antonio; Afonso, Maria del Mar; Yesilada, Erdem; Monsalve, Francisco; González, Paulo; Droguett, Daniel; Schmeda-Hirschmann, Guillermo

2011-01-01

307

Schwartzian derivative for multidimensional maps and flows  

SciTech Connect

A generalization of Schwartzian derivative to maps and flows in the space R{sup n} and in infinite-dimensional spaces is introduced. It is used to study the type of stability loss (soft or hard) for fixed points and periodic trajectories of diffeo-morphisms and flows. In particular, an example of a partial differential equation of reaction-diffusion type is presented for which the conditions of soft loss of stability of a spatially homogeneous solution are verified.

Sataev, E A [Obninsk State Technical University for Nuclear Power Engineering, Obninsk, Kaluga Region (Russian Federation)

1999-02-28

308

Uncertainty estimates for derivatives and intercepts  

SciTech Connect

Straight line least squares fits of experimental data are widely used in the analysis of test results to provide derivatives and intercepts. A method for evaluating the uncertainty in these parameters is described. The method utilizes conventional least squares results and is applicable to experiments where the independent variable is controlled, but not necessarily free of error. A Monte Carlo verification of the method is given.

Clark, E.L.

1994-09-01

309

A soluble and multichromic conducting polythiophene derivative  

Microsoft Academic Search

A new soluble polythiophene derivative was synthesized by both chemical and electrochemical oxidative polymerization of 1-4-nitrophenyl-2,5-di(2-thienyl)-1H-pyrrole (SNSNO2). Chemical method produces a polymer which is completely soluble in organic solvents. The structures of both the monomer and the soluble polymer were elucidated by 1H and 13C-NMR and FTIR. The average molecular weight has been determined by GPC to be Mn=6.3×103 for

Serhat Varis; Metin Ak; Cihangir Tanyeli; Idris Mecidoglu Akhmedov; Levent Toppare

2006-01-01

310

Triamine chelants, their derivatives, complexes and conjugates  

DOEpatents

A group of functionalized triamine chelants and their derivatives that form complexes with radioactive metal ions are disclosed. The complexes can be covalently attached to a protein or an antibody or antibody fragment and used for therapeutic and/or diagnostic purposes. The chelants are of the formula, as shown in the accompanying diagrams, wherein n, m, R, R{sup 1}, R{sup 2} and L are defined in the specification.

Troutner, D.E.; John, C.S.; Pillai, M.R.A.

1995-03-07

311

?-Tetralone derivatives as inhibitors of monoamine oxidase.  

PubMed

In the present study, a series of fifteen ?-tetralone (3,4-dihydro-2H-naphthalen-1-one) derivatives were synthesised and evaluated as inhibitors of recombinant human monoamine oxidase (MAO) A and B. The ?-tetralone derivatives examined are structurally related to a series of chromone (1-benzopyran-4-one) derivatives which has previously been shown to act as MAO-B inhibitors. The results document that the ?-tetralones are highly potent MAO-B inhibitors with all compounds exhibiting IC50 values in the nanomolar range (<78nM). Although most compounds are selective inhibitors of MAO-B, the ?-tetralones are also potent MAO-A inhibitors with ten compounds exhibiting IC50 values in the nanomolar range (<792nM). The most potent MAO-B inhibitor, 6-(3-iodobenzyloxy)-3,4-dihydro-2H-naphthalen-1-one, exhibits an IC50 value of 4.5nM with a 287-fold selectivity for MAO-B over the MAO-A isoform, while the most potent MAO-A inhibitor, 6-(3-cyanobenzyloxy)-3,4-dihydro-2H-naphthalen-1-one, exhibits an IC50 value of 24nM with a 3.25-fold selectivity for MAO-A. Analyses of the structure-activity relationships for MAO inhibition show that substitution on the C6 position of the ?-tetralone moiety is a requirement for MAO-A and MAO-B inhibition, and that a benzyloxy substituent on this position is more favourable for MAO-A inhibition than phenylethoxy and phenylpropoxy substitution. For MAO-B inhibition, alkyl and halogen substituents on the meta and para positions of the benzyloxy ring enhance inhibitory potency. It may be concluded that ?-tetralone derivatives are promising leads for design of therapies for Parkinson's disease and depression. PMID:24794105

Legoabe, Lesetja J; Petzer, Anél; Petzer, Jacobus P

2014-06-15

312

Deriving test plans from architectural descriptions  

Microsoft Academic Search

The paper presents an approach to derive test plansfor the conformance testing of a system implementationwith respect to the formal description of its SoftwareArchitecture (SA). The SA describes a system in termsof its components and connections, therefore the derivedtest plans address the integration testing phase.We base our approach on a Labelled Transition System(LTS) modeling the SA dynamics, and on suitable

Antonia Bertolino; Flavio Corradini; Henry Muccini

2000-01-01

313

Long-memory volatility in derivative hedging  

NASA Astrophysics Data System (ADS)

The aim of this work is to take into account the effects of long memory in volatility on derivative hedging. This idea is an extension of the work by Fedotov and Tan [Stochastic long memory process in option pricing, Int. J. Theor. Appl. Finance 8 (2005) 381-392] where they incorporate long-memory stochastic volatility in option pricing and derive pricing bands for option values. The starting point is the stochastic Black-Scholes hedging strategy which involves volatility with a long-range dependence. The stochastic hedging strategy is the sum of its deterministic term that is classical Black-Scholes hedging strategy with a constant volatility and a random deviation term which describes the risk arising from the random volatility. Using the fact that stock price and volatility fluctuate on different time scales, we derive an asymptotic equation for this deviation in terms of the Green's function and the fractional Brownian motion. The solution to this equation allows us to find hedging confidence intervals.

Tan, Abby

2006-10-01

314

Antithyroid effects of coal-derived pollutants  

SciTech Connect

Endemic goiter in iodide-sufficient areas of the United States and Colombia has been linked to watersheds rich in coal and shale, which several reports suggest are the source of water-borne goitrogens. In this report the potential antithyroid activities of aqueous coal and shale extracts and of compounds identified in aqueous effluents from coal conversion processes were assayed in thyroid peroxidase (TPO) and thyroid slice systems. Aqueous extracts of coal and black shale were potent inhibitors of TPO or [sup 125]I organification by thyroid slices. The most abundant water-soluble compounds derived from coal are dihydroxyphenols, thiocyanate, disulfides, and hydroxypyridines. The dihydroxyphenols resorcinol, 2-methylresorcinol, and 5-methylresorcinol (orcinol) were 26.7, 22.5, and 7.2 times more potent, respectively, than the antithyroid drug 6-propylthiouracil (PTU). Other dihydroxyphenols and thiocyanate were less potent but comparable in activity to PTU. All dihydroxypridines and 3-hydroxypridine produced inhibitory effects comparable to PTU. None of the disulfides inhibited TPO. The antiperoxidase effects of combinations of two dihydroxyphenols or one dihydroxyphenol and SCN were additive, whereas the effects of a combination of four dihydroxyphenols at threshold inhibitory concentrations were synergistic. Thus, antithyroid effects may be greatly amplified by exposure to multiple coal-derived goitrogens and could be many times that produced by any one of the contributing pollutants. These results demonstrate that potent water-borne goitrogens are derived from coal and shale and that their contamination of water supplies could pose a serious threat of thyroid disorders.

Lindsay, R.H.; Hill, J.B. (Univ. of Alabama Medical School, Birmingham (United States)); Gaitan, E.; Cooksey, R.C. (Univ. of Mississippi, Jackson (United States)); Jolley, R.L. (Oak Ridge National Lab., TN (United States))

1992-12-01

315

Affinity of guanosine derivatives for polycytidylate revisited  

NASA Technical Reports Server (NTRS)

Evidence is presented for complexation of guanosine 5'-monophosphate 2-methylimidazolide (2-MeImpG) with polycytidylate (poly(C)) at pH 8.0 and 23 degrees C in the presence of 1.0 M NaCl2 and 0.2 M MgCl2 in water. The association of 2-MeImpG with poly(C) was investigated using UV-vis spectroscopy as well as by monitoring the kinetics of the nucleophilic substitution reaction of the imidazole moiety by amines. The results of both methods are consistent with moderately strong poly(C) 2-MeImpG complexation and the spectrophotometric measurements allowed the construction of a binding isotherm with a concentration of 2-MeImpG equal to 5.55 +/- 0.15 mM at half occupancy. UV spectroscopy was employed to establish the binding of other guanosine derivatives on poly(C). These derivatives are guanosine 5'-monophosphate (5'GMP), guanosine 5'-monophosphate imidazolide (ImpG), and guanosine 5'-monophosphate morpholidate (morpG). Within experimental error these guanosine derivatives exhibit the same affinity for poly(C) as 2-MeImpG.

Kanavarioti, A.; Hurley, T. B.; Baird, E. E.

1995-01-01

316

[A novel naphthalene derivative from Aloe barbadensis].  

PubMed

To investigate the chemical constituents of A. barbadensis, aqueous extract of the plant was subjected to preparative medium pressure liquid chromatography (MPLC). The chemical structures were mainly determined by spectroscopic evidences (UV, IR, HR-MS, 1H NMR, 13C NMR, HSQC, 1H-1H COSY and HMBC) and chemical methods. A new O, O, O-triglucosylated naphthalene derivative, together with two known 6-phenyl-2-pyrone derivatives and four 5-methylchromones, were isolated and identified as 1-((3-((4- O-beta-D-glucopyranosyl)-beta-D-xylopyranosyloxymethyl)-1-hydroxy-8-alpha-L-rhamnopyranosyloxy)naphthalene-2-y])-ethanone (1), 10-O-beta-D-glucopyranosyl aloenin (2), aloenin B (3), aloesin (4), 8-C-glucosyl-(R)-aloesol (5), 8-C-glucosyl-7-O-methyl-(S)-aloesol (6), and isoaloeresin D (7). Compound 1 is a novel naphthalene derivative and named as aloveroside B, compounds 2-3 are isolated from this Aloe species for the first time. PMID:23888696

Wu, Xiao-Fang; Wan, Jin-Zhi; Luo, Bing-Jun; Yang, Miao-Rong; Ding, Wen-Jing; Zhong, Jia-Sheng

2013-05-01

317

Novel dehydroepiandrosterone derivatives with antiapoptotic, neuroprotective activity.  

PubMed

DHEA analogues with modifications at positions C3 or C17 were synthesized and evaluated for neuroprotective activity against the neural-crest-derived PC12 cell model of serum deprivation-induced apoptosis. The most potent compounds were the spiro-epoxy derivatives 17beta-spiro[5-androstene-17,2'-oxiran]-3beta-ol (20), (20S)-3beta,21-dihydroxy-17beta,20-epoxy-5-pregnene (23), and (20R)-3beta,21-dihydroxy-17alpha,20-epoxy-5-pregnene (27) with IC(50) values of 0.19 +/- 0.01, 99.0 +/- 4.6, and 6.4 +/- 0.3 nM, respectively. Analogues 20, 23, and 27, up to the micromolar range of concentrations, were unable to activate estrogen receptor alpha and beta (ERalpha and ERbeta) or to interfere with ER-dependent gene expression significantly. In addition, they were unable to stimulate the growth of Ishikawa, MCF-7, and LNCaP cells. Our results suggest that the spiro-epoxyneurosteroid derivatives 20, 23, and 27 may prove to be lead molecules for the synthesis of novel neuroprotective agents. PMID:19845386

Calogeropoulou, Theodora; Avlonitis, Nicolaos; Minas, Vassilios; Alexi, Xanthippi; Pantzou, Athanasia; Charalampopoulos, Ioannis; Zervou, Maria; Vergou, Varvara; Katsanou, Efrosini S; Lazaridis, Iakovos; Alexis, Michael N; Gravanis, Achille

2009-11-12

318

Correlation algorithms for ionization energies. Alkyl derivatives  

SciTech Connect

A concise derivation of a set of correlative equations for ionization potentials of alkyl molecules is presented. Derivations are based on the restricted HF-SCF approach and, in addition to the impositions common to that frame (e.g., rigid-core approximation, Koopmans' theorem, etc.), it also invokes a separation of density matrices for the chromophore (X) and substituent (S) segments of an XS molecule, a separation of peel and core electronic parts (i.e., peel/core strong-orthogonality requirement), a multipole expansion of the S potential, a partial neglect of correlation energies, and a segmental partitioning of the substituent alkyl chain. The primary defects of the derivations are associated with the partial neglect of correlation and substituent exchange effects. The various algorithms are tested on a pool of 200 alkylated molecules. The first algorithm, model 1, treats the situation in which the chromophore X is maintained constant and the substituent S is allowed to vary, whereas the second algorithm, model 2, allows variability of both S and S. Both algorithms provide faithful representations of experiment. 20 references, 7 figures, 5 tables.

McGlynn, S.P.; Langsjoen, A.M.; Hochmann, P.; Brint, P.; Findley, G.L.

1985-01-01

319

Preheating in derivatively coupled inflation models  

SciTech Connect

We study preheating in theories where the inflaton couples derivatively to scalar and gauge fields. Such couplings may dominate in, for example, models of natural inflation, in which the flatness of the inflaton potential is related to an approximate shift symmetry of the inflaton. We compare our results with previously studied models with non-derivative couplings. For sufficiently heavy scalar matter, parametric resonance is ineffective in reheating the universe, because the couplings of the inflaton to matter are very weak. If scalar matter fields are light, derivative couplings lead to long-wavelength instabilities that drive matter fields to non-zero expectation values. In this case however, long-wavelength fluctuations of the light scalar are produced during inflation, leading to a host of cosmological problems. In contrast, axion-like couplings of the inflaton to a gauge field do not lead to production of long-wavelength fluctuations during inflation. However, again because of the weakness of the couplings to the inflaton, parametric resonance is not effective in producing gauge field quanta.

Armendariz-Picon, Cristian; Trodden, Mark; West, Eric J, E-mail: armen@physics.syr.edu, E-mail: trodden@physics.syr.edu, E-mail: ejwest@physics.syr.edu [Cosmology Group, Department of Physics, Syracuse University, Syracuse, NY 13244-1130 (United States)

2008-04-15

320

GENERALIZED WHITE NOISE OPERATOR FIELDS AND QUANTUM WHITE NOISE DERIVATIVES  

Microsoft Academic Search

Regarding a Fock space operator as a function of quantum white noise = ( at;a t ; t2 T ), we introduce its quantum white noise derivatives (qwn- derivatives) as a kind of functional derivatives with respect to at and a t . We prove that every white noise operator is dierentiable and the qwn-derivatives form a gen- eralized white

Un Cig Ji; Nobuaki Obata

321

Phase change ink comprising colorants derived from plants and insects  

US Patent & Trademark Office Database

A phase change ink composition including a wax; an optional dispersant; an optional synergist; and a naturally-derived colorant wherein the naturally-derived colorant is a colorant derived from a plant, a colorant derived from an insect, or a mixture or combination thereof.

2013-12-31

322

Expansion Formulas in Terms of Integer-Order Derivatives for the Hadamard Fractional Integral and Derivative  

Microsoft Academic Search

We obtain series expansion formulas for the Hadamard fractional integral and fractional derivative of a smooth function. When considering finite sums only, an upper bound for the error is given. Numerical simulations show the efficiency of the approximation method.

Shakoor Pooseh; Ricardo Almeida; Delfim F. M. Torres

2012-01-01

323

DME-Derived Positions Compared with MLS- and ILS-Derived Positions.  

National Technical Information Service (NTIS)

From Distance Measurement Equipment (DME) data recorded during Microwave Landing System (MLS) flight trials, the positions of the aircraft was determined by postprocessing and compared with the MLS and Instrument Landing System (ILS) derived positions. An...

P. J. Hoogeboom

1990-01-01

324

Comparison of NOAA's Operational AVHRR-Derived Cloud Amount to Other Satellite-Derived Cloud Climatologies  

Microsoft Academic Search

Abstract A comparison is made between a new operational NOAA AVHRR global cloud amount,product to those from established satellite-derived cloud climatologies. The new operational NOAA AVHRR cloud amount,is derived using the cloud detection scheme,in the extended Clouds from AVHRR (CLAVR-x) system. The cloud mask within CLAVR-x is a replacement for the CLAVR-1 cloud mask. Previous analysis of the CLAVR-1 cloud

Sarah M. Thomas; Andrew K. Heidinger; Michael J. Pavolonis

2004-01-01

325

Comparison of NOAA's Operational AVHRR-Derived Cloud Amount to Other Satellite-Derived Cloud Climatologies  

Microsoft Academic Search

A comparison is made between a new operational NOAA Advanced Very High Resolution Radiometer (AVHRR) global cloud amount product to those from established satellite-derived cloud climatologies. The new operational NOAA AVHRR cloud amount is derived using the cloud detection scheme in the extended Clouds from AVHRR (CLAVR-x) system. The cloud mask within CLAVR-x is a replacement for the Clouds from

Sarah M. Thomas; Andrew K. Heidinger; Michael J. Pavolonis

2004-01-01

326

Hydroxylated Sclerosporin Derivatives from the Marine-derived Fungus Cadophora malorum†  

PubMed Central

The marine-derived fungus Cadophora malorum was isolated from the green alga Enteromorpha sp. Growth on a biomalt medium supplemented with sea salt yielded an extract from which we have isolated sclerosporin and four new hydroxylated sclerosporin derivatives, namely 15-hydroxysclerosporin (2), 12-hydroxysclerosporin (3), 11-hydroxysclerosporin (4) and 8-hydroxysclerosporin (5). The compounds were evaluated in various biological activity assays. Compound 5 showed a weak fat-accumulation inhibitory activity against 3T3-L1 murine adipocytes.

Almeida, Celso; Eguereva, Ekaterina; Kehraus, Stefan; Siering, Carsten; Konig, Gabriele M.

2010-01-01

327

Facile (Triazolyl)methylation of MACOS-derived Benzofused Sultams Utilizing ROMP-derived OTP Reagents  

PubMed Central

A combination of MACOS scale-out and ROMP-derived oligomeric triazole phosphates (OTPn) have been successfully utilized for the preparation of a 106-member library of triazole containing benzothiaoxazepine-1,1-dioxides. This report demonstrates the utilization of a suite of soluble OTPn reagents for facile (triazolyl)methylation of 10 MACOS-derived sultam scaffolds in purification-free process for parallel synthesis of small molecule collections for HTS.

Faisal, Saqib; Ullah, Farman; Maity, Pradip K.; Rolfe, Alan; Samarakoon, Thiwanka B.; Porubsky, Patrick; Neuenswander, Benjamin; Lushington, Gerald H.; Basha, Fatima Z.; Organ, Michael G.

2012-01-01

328

A new lysine derivative and new 3-bromopyrrole carboxylic acid derivative from two marine sponges.  

PubMed

A novel lysine derivative, 1, has been isolated from the marine sponge Axinyssa terpnis, in addition to 4alpha-isocyanogorgon-11-ene and related compounds (2-4). From the marine sponge Axinella carteri, the new 3-bromopyrrole carboxylic acid derivative, 5, was obtained along with the known compounds aldisin (6) and 2-bromoaldisin (7). Both sponges were collected from Chuuk Atoll, Federated States of Micronesia. The compounds were characterized by spectroscopic and chemical methods. PMID:9548881

Li, C J; Schmitz, F J; Kelly-Borges, M

1998-03-01

329

Biologic Rhythms Derived from Siberian Mammoths Hairs  

SciTech Connect

Hair is preserved for millennia in permafrost; it enshrines a record of biologic rhythms and offers a glimpse at chronobiology as it was in extinct animals. Here we compare biologic rhythms gleaned from mammoth's hairs with those of modern human hair. Four mammoths' hairs came from varying locations in Siberia 4600 km, four time zones, apart ranging in age between 18,000 and 20,000 years before present. We used two contemporaneous human hairs for comparison. Power spectra derived from hydrogen isotope ratios along the length of the hairs gave insight into biologic rhythms, which were different in the mammoths depending on location and differed from humans. Hair growth for mammoths was {approx}31 cms/year and {approx}16 cms/year for humans. Recurrent annual rhythms of slow and fast growth varying from 3.4 weeks/cycles to 8.7 weeks/cycles for slow periods and 1.2 weeks/cycles to 2.2 weeks/cycles for fast periods were identified in mammoth's hairs. The mineral content of mammoth's hairs was measured by electron microprobe analysis (k-ratios), which showed no differences in sulfur amongst the mammoth hairs but significantly more iron then in human hair. The fractal nature of the data derived from the hairs became evident in Mandelbrot sets derived from hydrogen isotope ratios, mineral content and geographic location. Confocal microscopy and scanning electron microscopy showed varied degrees of preservation of the cuticle largely independent of age but not location of the specimens. X-ray fluorescence microprobe and fluorescence computed micro-tomography analyses allowed evaluation of metal distribution and visualization of hollow tubes in the mammoth's hairs. Seasonal variations in iron and copper content combined with spectral analyses gave insights into variation in food intake of the animals. Biologic rhythms gleaned from power spectral plots obtained by modern methods revealed life style and behavior of extinct mega-fauna.

M Spilde; A Lanzirotti; C Qualls; G Phillips; A Ali; L Agenbroad; O Appenzeller

2011-12-31

330

Antithyroid effects of coal-derived pollutants.  

PubMed

Endemic goiter in iodide-sufficient areas of the United States and Colombia has been linked to watersheds rich in coal and shale, which several reports suggest are the source of water-borne goitrogens. In this report the potential antithyroid activities of aqueous coal and shale extracts and of compounds identified in aqueous effluents from coal conversion processes were assayed in thyroid peroxidase (TPO) and thyroid slice systems. Aqueous extracts of coal and black shale were potent inhibitors of TPO or 125I organification by thyroid slices. The most abundant water-soluble compounds derived from coal are dihydroxy-phenols, thiocyanate, disulfides, and hydroxypyridines. The dihydroxyphenols resorcinol, 2-methylresorcinol, and 5-methylresorcinol (orcinol) were 26.7, 22.5, and 7.2 times more potent, respectively, than the antithyroid drug 6-propylthiouracil (PTU). Other dihydroxyphenols and thiocyanate were less potent but comparable in activity to PTU. All dihydroxypyridines and 3-hydroxypyridine produced inhibitory effects comparable to PTU. None of the disulfides inhibited TPO. The antiperoxidase effects of combinations of two dihydroxyphenols or one dihydroxyphenol and SCN were additive, whereas the effects of a combination of four dihydroxyphenols at threshold inhibitory concentrations were synergistic, resulting in net effects equivalent to or greater than the sum of the individual effects. Thus, antithyroid effects may be greatly amplified by exposure to multiple coal-derived goitrogens and could be many times that produced by any one of the contributing pollutants. These results demonstrate that potent water-borne goitrogens are derived from coal and shale and that their contamination of water supplies could pose a serious threat of thyroid disorders. PMID:1281508

Lindsay, R H; Hill, J B; Gaitan, E; Cooksey, R C; Jolley, R L

1992-12-01

331

Vibrational Relaxation in Several Derivatives of Benzene  

NASA Astrophysics Data System (ADS)

Acoustical spectroscopy at frequencies up to 10 GHz gives the possibility of the investigation of liquid substances, where the relaxation process observed is caused by energy transfer between translational and vibrational degrees of freedom. The compounds presented in this article belong to this group of liquids. The acoustic investigations in the group of benzene derivatives, particularly research of the dependencies of acoustic parameters and the structure of organic liquids, demonstrated some interesting regularities in the group of these compounds in gas and liquid states. In this article, the results of research on five cyclic liquids: bromo-, chloro-, fluoro-, iodo-, and nitrobenzene as well as toluene and aniline are discussed and compared to benzene. The acoustic relaxation observed in all these compounds was found to result from Kneser's processes (vibrational relaxation). Based on investigations reported in this article, as well as by other authors, and taking into account experimental and literature data concerning a great number of compounds, one can draw a conclusion that almost all acoustic relaxation (Kneser-type) processes in liquids can be described using a single relaxation time. It also seems that all vibrational degrees of freedom of the molecule take part in this process. It is known that the appearance of differences in transition probabilities could be caused by additional attraction in interactions of molecules having dipole moments. Halogen derivatives have higher values of dipole moments than benzene. This difference could be responsible for the difference of transition probabilities and changes in the relaxation times. However, benzene derivatives with amino, nitro, and methyl groups and halides show the other type of relaxation.

Linde, Bogumi? B. J.; Skrodzka, Ewa B.; Lezhnev, Niko?aj B.

2012-04-01

332

Chemically derived, ultrasmooth graphene nanoribbon semiconductors.  

PubMed

We developed a chemical route to produce graphene nanoribbons (GNR) with width below 10 nanometers, as well as single ribbons with varying widths along their lengths or containing lattice-defined graphene junctions for potential molecular electronics. The GNRs were solution-phase-derived, stably suspended in solvents with noncovalent polymer functionalization, and exhibited ultrasmooth edges with possibly well-defined zigzag or armchair-edge structures. Electrical transport experiments showed that, unlike single-walled carbon nanotubes, all of the sub-10-nanometer GNRs produced were semiconductors and afforded graphene field effect transistors with on-off ratios of about 10(7) at room temperature. PMID:18218865

Li, Xiaolin; Wang, Xinran; Zhang, Li; Lee, Sangwon; Dai, Hongjie

2008-02-29

333

Pricing financial derivatives with neural networks  

NASA Astrophysics Data System (ADS)

Neural network algorithms are applied to the problem of option pricing and adopted to simulate the nonlinear behavior of such financial derivatives. Two different kinds of neural networks, i.e. multi-layer perceptrons and radial basis functions, are used and their performances compared in detail. The analysis is carried out both for standard European options and American ones, including evaluation of the Greek letters, necessary for hedging purposes. Detailed numerical investigation show that, after a careful phase of training, neural networks are able to predict the value of options and Greek letters with high accuracy and competitive computational time.

Morelli, Marco J.; Montagna, Guido; Nicrosini, Oreste; Treccani, Michele; Farina, Marco; Amato, Paolo

2004-07-01

334

Effective interaction derived from the BAGEL approach  

NASA Astrophysics Data System (ADS)

Matrix inversion techniques are used to derive an effective hamiltonian for shell-model calculations, which accounts for correlations outside the shell-model space. It is demonstrated that the BAGEL approach leads to a very powerful tool to account for the effects of large Q-spaces in a reliable way. An energy-dependent formulation yields stable results even for cases which are divergent in the perturbative approach due to the presence of intruder states. A first application employing modern one-boson exchange potentials produces results which are in very satisfactory agreement with empirical data.

Skouras, L. D.; Müther, H.

1990-08-01

335

Dietary derived compounds in cancer chemoprevention  

PubMed Central

Cancer chemoprevention is defined as the application of natural or synthetic agents to suppress or reverse cancer development and progression. In this field especially diet derived compounds have recently attracted researchers’ attention as potential therapeutics generally exerting low toxicity compared with regular drugs. This review presents a survey of recent findings concerning the most promising dietary chemopreventive agents such as green tea polyphenols (i.e. catechins), long-chain polyunsaturated fatty acids, carotenoids, glucosinolates/isothiocyanates, vitamins (i.e. vitamin D and folate) and minerals (i.e. calcium and selenium). Molecular targets involved in intrinsic pathways affected by these natural compounds are also shortly discussed.

Rzeski, Wojciech

2012-01-01

336

Antibacterial endiandric acid derivatives from Beilschmiedia anacardioides.  

PubMed

Three endiandric acid derivatives, beilschmiedic acids A, B and C were isolated from the stem bark of Beilschmiedia anacardioides together with the known beta-sitosterol. Their structures were established by means of modern spectroscopic techniques. The relative configuration of compound 1 was determined by single crystal X-ray analysis. The antibacterial activities of compounds A,B,C were evaluated in vitro against five strains of microbes. Compound C showed strong activity against Bacillus subtilis, Micrococcus luteus and Streptococcus faecalis (MICs below 23 microM). This Compound was more active than the reference antibiotic ampicillin against B. subtilis and M. luteus. PMID:19345383

Chouna, Jean Rodolphe; Nkeng-Efouet, Pepin Alango; Lenta, Bruno Ndjakou; Devkota, Krishna Prasad; Neumann, Beate; Stammler, Hans-Georg; Kimbu, Samuel Fon; Sewald, Norbert

2009-03-01

337

Studies on some derivatives of oxamniquine  

SciTech Connect

On the basis of the remarkable biological similarities between hycanthone and oxamniquine and as a sequel to our finding that some esters of hycanthone are active against hycanthone-resistant schistosomes, we prepared oxamniquine acetate, oxamniquine N-methylcarbamate, and four substituted phenylsulfonohydrazones of oxamniquine aldehyde. These compounds were tested for their effect on survival of and on (/sup 3/H)uridine incorporation into hycanthone-sensitive and -resistant Schistosoma mansoni. All of these derivatives were effective to a greater or lesser degree in killing worms and in inhibiting (/sup 3/H)uridine incorporation in the sensitive strain, but none was effective in the resistant strain.

el-Hamouly, W.; Pica-Mattoccia, L.; Cioli, D.; Schwartz, H.M.; Archer, S.

1988-08-01

338

Sesquiterpenoid derivatives from Ferula ferulaeoides (Steud.) Korov.  

PubMed

Eight sesquiterpenoids, named Ferulaeone A-H (1-8), and seven known sesquiterpenoid derivatives were isolated from the roots of Ferula ferulaeoides (Steud.) Korov. Their structures were established by comprehensive spectroscopic analysis, and biosynthetic pathways leading to these compounds were proposed. The cytotoxicity of all these isolates against HepG2, MCF-7, and C6 cancer cell lines was evaluated and compounds 6-11, 13 exihibited various degrees of cytotoxic effect. Among them, compounds 9-11 displayed the highest potency against C6 with IC(50) values 34, 36, and 31 ?M, respectively. PMID:23218017

Meng, He; Li, Guoyu; Huang, Jian; Zhang, Ke; Wei, Xiuyan; Ma, Yueping; Zhang, Cui; Wang, Jinhui

2013-02-01

339

Antibacterial anthranilic acid derivatives from Geijera parviflora.  

PubMed

Five anthranilic acid derivatives, a mixture I of three new compounds 11'-hexadecenoylanthranilic acid (1), 9'-hexadecenoylanthranilic acid (2), and 7'-hexadecenoylanthranilic acid (3), as well as a new compound 9,12,15-octadecatrienoylanthranilic acid (4) together with a new natural product, hexadecanoylanthranilic acid (5), were isolated from Geijera parviflora Lindl. (Rutaceae). Their structures were elucidated by extensive spectroscopic measurements, and the positions of the double bonds in compounds 1-3 of the mixture I were determined by tandem mass spectrometry employing ozone-induced dissociation. The mixture I and compound 5 showed good antibacterial activity against several Gram-positive strains. PMID:24370663

Shou, Qingyao; Banbury, Linda K; Maccarone, Alan T; Renshaw, Dane E; Mon, Htwe; Griesser, Stefani; Griesser, Hans J; Blanksby, Stephen J; Smith, Joshua E; Wohlmuth, Hans

2014-03-01

340

Hematopoietic growth factor derived from T lymphocytes  

US Patent & Trademark Office Database

A T cell-derived colony stimulating factor ("TC-CSF") may be isolated from media conditioned with T lymphocyte cells. TC-CSF stimulates formation of colonies composed of granulocytes, macrophages, megakaryocytes, fibrocytic stromal cells, lymphocytes, and mixed colonies of granulocytes and macrophages. Anion exchange chromatography may be employed in conjunction with gel filtration and rpHPLC to isolate TC-CSF. Human TC-CSF and murine TC-CSF cDNA, MRNA, genomic DNA nucleotide and amino acid sequences, expression products, pharmaceutical formulations and antibody materials are specifically provided.

2001-07-03

341

Geometric derivation of the chronometric redshift.  

PubMed Central

The chronometric redshift-distance relation z = tan 2(1/2rho), where rho is the distance in radians in the Einstein metric, is derived by an elementary geometric analysis comparable to that in traditional analysis of the expanding universe model. The differential dTt of Einstein time evolution Tt through time t, as applied to the local Minkowski coordinates x, takes the form sec2(1/2t). At the point of observation t = rho, implying that for a sufficiently localized source, observed wave lengths are a factor of sec2(1/2rho) greater than the corresponding emitted wave lengths.

Segal, I E

1993-01-01

342

Enhanced cubic optical nonlinearity of oligoazine derivatives  

NASA Astrophysics Data System (ADS)

We report a large positive third-order optical nonlinearity of synthesized oligoazine derivatives (OADs) using z-scan technique at 532 nm by Q-switched Nd:YAG laser. Optical band gap of OADs shrinks with increasing repeated units. Origin of large cubic nonlinearity is in the extensive ?-electron delocalization. We obtained the values of and in OADs. Moreover, values of optical nonlinearity of OADs show reasonable agreement with the theoretically predicted values. We have shown OADs could be used as good reverse saturable absorber and self-focusing materials. Optical limiting, due to reverse saturable absorption, has also been successfully demonstrated at 532 nm.

Singh, Vijender; Aghamkar, Praveen; Malik, Rajesh Kumar

2014-06-01

343

Thermochemical properties of three piperidine derivatives  

Microsoft Academic Search

The standard (p\\u000a o=0.1 MPa) molar energies of combustion for the crystalline 1-benzyl-4-piperidinol and 4-piperidine-piperidine, and for the\\u000a liquid 4-benzylpiperidine, were measured by static bomb calorimetry, in oxygen, at T=298.15 K. The standard molar enthalpies of sublimation or vaporization, at T=298.15 K, of these three compounds were determined by Calvet microcalorimetry.\\u000a \\u000a Those values were used to derive the standard molar

M. A. V. Ribeiro da Silva; Joana I. T. A. Cabral

2007-01-01

344

Exact cosmological solutions with nonminimal derivative coupling  

SciTech Connect

We consider a gravitational theory of a scalar field {phi} with nonminimal derivative coupling to curvature. The coupling terms have the form {kappa}{sub 1}R{phi}{sub ,{mu}}{phi}{sup ,{mu}} and {kappa}{sub 2}R{sub {mu}}{sub {nu}}{phi}{sup ,{mu}}{phi}{sup ,{nu}}, where {kappa}{sub 1} and {kappa}{sub 2} are coupling parameters with dimensions of length squared. In general, field equations of the theory contain third derivatives of g{sub {mu}}{sub {nu}} and {phi}. However, in the case -2{kappa}{sub 1}={kappa}{sub 2}{identical_to}{kappa}, the derivative coupling term reads {kappa}G{sub {mu}}{sub {nu}}{phi}{sup ,{mu}}{phi}{sup ,{nu}} and the order of corresponding field equations is reduced up to second one. Assuming -2{kappa}{sub 1}={kappa}{sub 2}, we study the spatially-flat Friedman-Robertson-Walker model with a scale factor a(t) and find new exact cosmological solutions. It is shown that properties of the model at early stages crucially depend on the sign of {kappa}. For negative {kappa}, the model has an initial cosmological singularity, i.e., a(t){approx}(t-t{sub i}){sup 2/3} in the limit t{yields}t{sub i}; and for positive {kappa}, the Universe at early stages has the quasi-de Sitter behavior, i.e., a(t){approx}e{sup Ht} in the limit t{yields}-{infinity}, where H=(3{radical}({kappa})){sup -1}. The corresponding scalar field {phi} is exponentially growing at t{yields}-{infinity}, i.e., {phi}(t){approx}e{sup -t/{radical}}{sup ({kappa})}. At late stages, the Universe evolution does not depend on {kappa} at all; namely, for any {kappa} one has a(t){approx}t{sup 1/3} at t{yields}{infinity}. Summarizing, we conclude that a cosmological model with nonminimal derivative coupling of the form {kappa}G{sub {mu}}{sub {nu}}{phi}{sup ,{mu}}{phi}{sup ,{nu}} is able to explain in a unique manner both a quasi-de Sitter phase and an exit from it without any fine-tuned potential.

Sushkov, Sergey V. [Department of General Relativity and Gravitation, Kazan State University, Kremlevskaya Str. 18, Kazan 420008 (Russian Federation) and Department of Mathematics, Tatar State University of Humanities and Education, Tatarstan Str. 2, Kazan 420021 (Russian Federation)

2009-11-15

345

Synthesis and Biological Activities of 4-Aminoantipyrine Derivatives Derived from Betti-Type Reaction  

PubMed Central

The present work deals with the synthesis and evaluation of biological activities of 4-aminoantipyrine derivatives derived from a three-component Betti reaction. The synthesis was initiated by the condensation of aromatic aldehyde, 4-aminoantipyrine, and 8-hydroxyquinoline in presence of fluorite as catalyst in a simple one-step protocol. The reactions were stirred at room temperature for 10–15?min achieving 92–95% yield. The structures of synthesized derivatives were established on the basis of spectroscopic and elemental analysis. All derivatives 4(a–h) were screened in vivo and in vitro for anti-inflammatory and anthelmintic activity against a reference drug, Diclofenac and Albendazole, respectively. The screening results show that compounds 4c, 4d, 4f, and 4h were found to possess potential anti-inflammatory activity while compounds 4a, 4b, 4e, and 4g are potent anthelmintic agents when compared with reference drugs, respectively. The bioactivity of these derivatives has also been evaluated with respect to Lipinski's rule of five using molinspiration cheminformatics software.

Meshram, Jyotsna

2014-01-01

346

Derive capillary pressure from well logs  

SciTech Connect

A new approach has been developed to estimate in-situ capillary pressure and relative permeability characteristics in the transition zone. The technique is based on incorporating petrophysical data measured on core samples with well log analysis. Relative permeability can be determined for both drainage and inhibition conditions using the matched capillary pressure data. A technique has been developed to extrapolate petro-physical data where core data is absent or not representative of in-situ conditions. It is based on using log data to derive a water saturation vs. depth profile in the transition zone of the formation of interest. The log-derived water saturation distribution is then correlated to generalized capillary pressure curves typical of the formation studied. The capillary pressure type curves are generated from available core data and other petrophysical information. Relative permeability curves are then generated using correlations based on Purcell's model. The technique can be used in multi-layered and homogeneous reservoirs provided that one homogeneous layer is at least 20 ft thick.

Ibrahim, A. (Suez Canal Univ. (Egypt)); Desbrandes, R.; Bassiouni, Z. (Louisiana State Univ., Baton Rouge, LA (United States))

1994-07-01

347

New derivative of carnosine for nanoparticle assemblies.  

PubMed

Carnosine (?-alanyl-l-histidine) is an endogenous dipeptide, extensively studied owing to its multifunctional activity exhibited in tissues of several animal species. This natural compound may act as a physiological buffer, ion-chelating agent (especially for copper(II) and zinc(II)), antioxidant and antiglycating agent. The main limit for the therapeutical uses of carnosine is the rapid hydrolysis mostly in human plasma by carnosinase. The chemical derivatization of carnosine is a promising strategy to improve the bioavailability of the dipeptide and facilitating the site-specific transport to different tissues. On this basis, a new carnosine derivative with biotin was synthesized and structurally characterized by NMR and MS measurements, with aim of exploiting the avidin-biotin technology that offers a universal system for selective delivery of any biotinylated agent. The stability of the new carnosine derivative towards the hydrolytic action of serum carnosinase as well as the copper(II) binding ability of the carnosine-biotin conjugate were also assessed. The binding affinity of the new molecular entity to avidin and streptavidin, investigated by a spectrophotometric assay, was exploited to functionalize avidin- and streptavidin-gold nanoparticles with the carnosine-biotin conjugate. PMID:24158014

Bellia, Francesco; Oliveri, Valentina; Rizzarelli, Enrico; Vecchio, Graziella

2013-12-01

348

Interface Pressures Derived from Oversize Compression Stockings  

PubMed Central

Objectives: To clarify interface pressures (IP) derived from class II and III oversize stockings. Methods: Healthy volunteers with legs fitting size S (n = 10), M (n = 6), or L (n = 6) stockings wore class II and III stockings of various sizes up to 5L. IPs were measured in the supine and the standing position with each stocking on. Results: In the subjects with size S legs, the IPs in the standing position while wearing S and M class III stockings were 43.5 ± 4.7 and 40.4 ± 5.4 mmHg respectively. These IPs were significantly higher than the IP while wearing the S size class II stocking (33.3 ± 5.9 mmHg). IPs derived from L, LL, 3L, 4L, 5L class III stockings were not significantly different from IP with the S size class II stocking. The results were similar for the subjects with size M legs while wearing the size M and L class III stockings and for the subjects with size L legs while wearing the size L and LL class III stockings vs. the appropriate size class II stocking. Conclusion: Based on these findings, a larger size class III stocking can provide similar or even higher IPs compared to an appropriate size class II stocking.

2012-01-01

349

Metabolism of hop-derived bitter acids.  

PubMed

In this study, in vitro metabolism of hop-derived bitter acids was investigated. Besides their well-known use as bitter compounds in beer, in several studies, bioactive properties have been related to these types of molecules. However, scientific data on the absorption, distribution, metabolism, and excretion aspects of these compounds are limited. More specific, in this study, ?-acids, ?-acids, and iso-?-acids were incubated with rabbit microsomes, and fractions were subjected to LC-MS/MS analysis for identification of oxidative biotransformation products. Metabolism of ?-acids was mainly characterized by conversion into hulupones and the formation of a series of tricyclic oxygenated products. The most important metabolites of ?-acids were identified as humulinones and hulupones. Iso-?-acids were found to be primarly metabolized into cis- and trans-humulinic acids, next to oxidized alloiso-?-acids. Interestingly, the phase I metabolites were highly similar to the oxidative degradation products in beer. These findings show a first insight into the metabolites of hop-derived bitter acids and could have important practical implications in the bioavailability aspects of these compounds, following ingestion of hop-based food products and nutraceuticals. PMID:23898921

Cattoor, Ko; Dresel, Michael; De Bock, Lies; Boussery, Koen; Van Bocxlaer, Jan; Remon, Jean-Paul; De Keukeleire, Denis; Deforce, Dieter; Hofmann, Thomas; Heyerick, Arne

2013-08-21

350

Molecular structures of new ciprofloxacin derivatives  

NASA Astrophysics Data System (ADS)

Two new derivatives from the ciprofloxacin fluoroquinoline family, 7-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-quinoline-3-methylcarbamate and 1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-(3-oxopyrazolo)[4,3-c]quinoline, were synthesised, tested for antibacterial activity and crystallised. Their molecular and crystal structures were determined. Tests in vitro reveal lower activities than for ciprofloxacin. Characteristic structural features of these compounds are comparable to data for other known fluoroquinolines. The bicyclic quinoline ring is planar in both compounds; the carbamate side chain and five-membered pyrazolo ring are almost coplanar with it. A piperazinyl ring exhibits a chair conformation. In the crystal packing of the carbamate analogue, two C-H⋯O interactions form a dimer. The pyrazolo derivative crystallises as solvate with 1.5 water molecules per quinoline molecule. In its crystal structure donor and acceptor functionalities form dimers, via hydrogen bonds, which are connected into an infinite pattern through hydrogen bonded water molecules.

Tomiši?, Zrinka Bani?; Kujundži?, Nedjeljko; Kraja?i?, Mirjana Bukvi?; Višnjevac, Aleksandar; Koji?-Prodi?, Biserka

2002-06-01

351

Primer on electricity futures and other derivatives  

SciTech Connect

Increased competition in bulk power and retail electricity markets is likely to lower electricity prices, but will also result in greater price volatility as the industry moves away from administratively determined, cost-based rates and encourages market-driven prices. Price volatility introduces new risks for generators, consumers, and marketers. Electricity futures and other derivatives can help each of these market participants manage, or hedge, price risks in a competitive electricity market. Futures contracts are legally binding and negotiable contracts that call for the future delivery of a commodity. In most cases, physical delivery does not take place, and the futures contract is closed by buying or selling a futures contract on or near the delivery date. Other electric rate derivatives include options, price swaps, basis swaps, and forward contracts. This report is intended as a primer for public utility commissioners and their staff on futures and other financial instruments used to manage price risks. The report also explores some of the difficult choices facing regulators as they attempt to develop policies in this area.

Stoft, S.; Belden, T.; Goldman, C.; Pickle, S.

1998-01-01

352

Active acoustic metamaterial with fractional derivative controller  

NASA Astrophysics Data System (ADS)

A class of active acoustic metamaterial (AAM) is presented. The proposed AAM consists of an acoustic transmission line connected in parallel to an array of Helmholtz resonators that are provided with actively controlled boundaries. In this manner, the AAM is in effect an assembly of periodic cells, each of which consists of a Helmholtz resonator connected in parallel to two sections of the transmission line. The two sections meet the Helmholtz resonator at its neck. The local control action at each Helmholtz resonator of a unit cell is generated by using a Fractional Derivative (FD) controller that relies in its operation on the measurement of the flow resulting from the deflection of the resonator boundary and the flow rates inside the two transmission line sections before and after the resonator. Such a single local control action is shown to be capable of controlling the local effective density and elasticity of each unit cell. A lumped-parameter model is developed to model the dynamics and control characteristics of the AAM under different gains and exponents of the FD controller. The model is exercised to demonstrate the ability of the FD controller in generating metamaterials with double negative effective density and elasticity over broad frequency ranges as compared to conventional Proportional and Derivative (PD) controllers. With such capabilities, the development of AAM with FD control action may provide viable means for generating desirable spatial distributions of density and elasticity over broad frequency band using a small number of control actuators.

Althamer, S.; Baz, A.

2014-03-01

353

Transthyretin-Derived Peptides as ?-Amyloid Inhibitors.  

PubMed

Self-association of ?-amyloid (A?) into soluble oligomers and fibrillar aggregates is associated with Alzheimer's disease pathology, motivating the search for compounds that selectively bind to and inhibit A? oligomerization and/or neurotoxicity. Numerous small-molecule inhibitors of A? aggregation or toxicity have been reported in the literature. However, because of their greater size and complexity, peptides and peptidomimetics may afford improved specificity and affinity as A? aggregation modulators compared to small molecules. Two divergent strategies have been employed in the search for peptides that bind A?: (i) using recognition domains corresponding to sequences in A? itself (such as KLVFF) and (ii) screening random peptide-based libraries. In this study, we propose a third strategy, specifically, designing peptides that mimic binding domains of A?-binding proteins. Transthyretin, a plasma transport protein that is also relatively abundant in cerebrospinal fluid, has been shown to bind to A?, inhibit aggregation, and reduce its toxicity. Previously, we identified strand G of transthyretin as a specific A? binding domain. In this work we further explore and define the necessary features of this binding domain. We demonstrate that peptides derived from transthyretin bind A? and inhibit its toxicity. We also show that, although both transthyretin and transthyretin-derived peptides bind A? and inhibit toxicity, they differ significantly in their effect on A? aggregation. PMID:24689444

Cho, Patricia Y; Joshi, Gururaj; Johnson, Jeffrey A; Murphy, Regina M

2014-07-16

354

Stemness is Derived from Thyroid Cancer Cells  

PubMed Central

Background: One hypothesis for thyroid cancer development is its derivation from thyroid cancer stem cells (CSCs). Such cells could arise via different paths including from mutated resident stem cells within the thyroid gland or via epithelial to mesenchymal transition (EMT) from malignant cells since EMT is known to confer stem-like characteristics. Furthermore, EMT is a critical process for epithelial tumor progression, local invasion, and metastasis formation. In addition, stemness provides cells with therapeutic resistance and is the likely cause of tumor recurrence. However, the relevance of EMT and stemness in thyroid cancer progression has not been extensively studied. Methods: To examine the status of stemness in thyroid papillary cancer, we employed a murine model of thyroid papillary carcinoma and examined the expression of stemness and EMT using qPCR and histochemistry in mice with a thyroid-specific knock-in of oncogenic Braf (LSL-Braf(V600E)/TPO-Cre). This construct is only activated at the time of thyroid peroxidase (TPO) expression in differentiating thyroid cells and cannot be activated by undifferentiated stem cells, which do not express TPO. Results: There was decreased expression of thyroid-specific genes such as Tg and NIS and increased expression of stemness markers, such as Oct4, Rex1, CD15, and Sox2 in the thyroid carcinoma tissue from 6-week-old BRAFV600E mice indicating the dedifferentiated status of the cells and the fact that stemness was derived in this model from differentiated thyroid cells. The decreased expression of the epithelial marker E-cadherin and increased EMT regulators including Snail, Slug, and TGF-?1 and TGF-?3, and the mesenchymal marker vimentin demonstrated the simultaneous progression of EMT and the CSC-like phenotype. Stemness was also found in a cancer thyroid cell line (named Marca cells) derived from one of the murine tumors. In this cell line, we also found that overexpression of Snail caused up-regulation of vimentin expression and up-regulation of stemness markers Oct4, Rex1, and CD15, with enhanced migration ability of the cells. We also showed that TGF-?1 was able to induce Snail and vimentin expression in the Marca cell thyroid cancer line, indicating the induction of EMT in these cells, and this induction of EMT and stemness was significantly inhibited by celastro a natural inhibitor of neoplastic cells. Conclusion: Our findings support our earlier hypothesis that stemness in thyroid cancer is derived via EMT rather than from resident thyroid stem cells. In mice with a thyroid-specific knock-in of oncogenic Braf (LSL-Braf(V600E)/TPO-Cre), the neoplastic changes were dependent on thyroid cell differentiation and the onset of stemness must have been derived from differentiated thyroid epithelial cells. Furthermore, celastrol suppressed TGF-?1 induced EMT in thyroid cancer cells and may have therapeutic potential.

Ma, Risheng; Bonnefond, Simon; Morshed, Syed A.; Latif, Rauf; Davies, Terry F.

2014-01-01

355

Tandem repeats derived from centromeric retrotransposons  

PubMed Central

Background Tandem repeats are ubiquitous and abundant in higher eukaryotic genomes and constitute, along with transposable elements, much of DNA underlying centromeres and other heterochromatic domains. In maize, centromeric satellite repeat (CentC) and centromeric retrotransposons (CR), a class of Ty3/gypsy retrotransposons, are enriched at centromeres. Some satellite repeats have homology to retrotransposons and several mechanisms have been proposed to explain the expansion, contraction as well as homogenization of tandem repeats. However, the origin and evolution of tandem repeat loci remain largely unknown. Results CRM1TR and CRM4TR are novel tandem repeats that we show to be entirely derived from CR elements belonging to two different subfamilies, CRM1 and CRM4. Although these tandem repeats clearly originated in at least two separate events, they are derived from similar regions of their respective parent element, namely the long terminal repeat (LTR) and untranslated region (UTR). The 5? ends of the monomer repeat units of CRM1TR and CRM4TR map to different locations within their respective LTRs, while their 3? ends map to the same relative position within a conserved region of their UTRs. Based on the insertion times of heterologous retrotransposons that have inserted into these tandem repeats, amplification of the repeats is estimated to have begun at least ~4 (CRM1TR) and ~1 (CRM4TR) million years ago. Distinct CRM1TR sequence variants occupy the two CRM1TR loci, indicating that there is little or no movement of repeats between loci, even though they are separated by only ~1.4 Mb. Conclusions The discovery of two novel retrotransposon derived tandem repeats supports the conclusions from earlier studies that retrotransposons can give rise to tandem repeats in eukaryotic genomes. Analysis of monomers from two different CRM1TR loci shows that gene conversion is the major cause of sequence variation. We propose that successive intrastrand deletions generated the initial repeat structure, and gene conversions increased the size of each tandem repeat locus.

2013-01-01

356

Antimalarial Activities of Dermaseptin S4 Derivatives  

PubMed Central

The hemolytic antimicrobial peptide dermaseptin S4 was recently shown to exert antimalarial activity. In this study, we attempted to understand the underlying mechanism(s) and identify derivatives with improved antimalarial activity. A number of dermaseptin S4 derivatives inhibited parasite growth with a 50% inhibitory concentration (IC50) in the micromolar range. Among these, the substituted S4 analog K4K20-S4 was the most potent (IC50 = 0.2 ?M), while its shorter version, K4-S4(1–13)a, retained a considerable potency (IC50 = 6 ?M). Both K4K20-S4 and K4-S4(1–13)a inhibited growth of the parasites more at the trophozoite stage than at the ring stage. Significant growth inhibition was observed after as little as 1 min of exposure to peptides and proceeded with nearly linear kinetics. The peptides selectively lysed infected red blood cells (RBC) while having a weaker effect on noninfected RBC. Thus, K4K20-S4 lysed trophozoites at concentrations similar to those that inhibited their proliferation, but trophozoites were >30-fold more susceptible than normal RBC to the lytic effect of K4K20-S4, the most hemolytic dermaseptin. The same trend was observed with K4-S4(1–13)a. The d isomers of K4K20-S4 or K4-S4(1–13)a were as active as the l counterparts, indicating that antimalarial activity of these peptides, like their membrane-lytic activity, is not mediated by specific interactions with a chiral center. Moreover, dissipation of transmembrane potential experiments with infected cells indicated that the peptides induce damage in the parasite's plasma membrane. Fluorescence confocal microscopy analysis of treated infected cells also indicated that the peptide is able to find its way through the complex series of membranes and interact directly with the intracellular parasite. Overall, the data showed that dermaseptins exert antimalarial activity by lysis of infected cells. Dermaseptin derivatives are also able to disrupt the parasite plasma membrane without harming that of the host RBC.

Krugliak, Miriam; Feder, Rina; Zolotarev, Vadim Y.; Gaidukov, Leonid; Dagan, Arie; Ginsburg, Hagai; Mor, Amram

2000-01-01

357

Antimalarial activities of dermaseptin S4 derivatives.  

PubMed

The hemolytic antimicrobial peptide dermaseptin S4 was recently shown to exert antimalarial activity. In this study, we attempted to understand the underlying mechanism(s) and identify derivatives with improved antimalarial activity. A number of dermaseptin S4 derivatives inhibited parasite growth with a 50% inhibitory concentration (IC(50)) in the micromolar range. Among these, the substituted S4 analog K(4)K(20)-S4 was the most potent (IC(50) = 0.2 microM), while its shorter version, K(4)-S4(1-13)a, retained a considerable potency (IC(50) = 6 microM). Both K(4)K(20)-S4 and K(4)-S4(1-13)a inhibited growth of the parasites more at the trophozoite stage than at the ring stage. Significant growth inhibition was observed after as little as 1 min of exposure to peptides and proceeded with nearly linear kinetics. The peptides selectively lysed infected red blood cells (RBC) while having a weaker effect on noninfected RBC. Thus, K(4)K(20)-S4 lysed trophozoites at concentrations similar to those that inhibited their proliferation, but trophozoites were >30-fold more susceptible than normal RBC to the lytic effect of K(4)K(20)-S4, the most hemolytic dermaseptin. The same trend was observed with K(4)-S4(1-13)a. The D isomers of K(4)K(20)-S4 or K(4)-S4(1-13)a were as active as the L counterparts, indicating that antimalarial activity of these peptides, like their membrane-lytic activity, is not mediated by specific interactions with a chiral center. Moreover, dissipation of transmembrane potential experiments with infected cells indicated that the peptides induce damage in the parasite's plasma membrane. Fluorescence confocal microscopy analysis of treated infected cells also indicated that the peptide is able to find its way through the complex series of membranes and interact directly with the intracellular parasite. Overall, the data showed that dermaseptins exert antimalarial activity by lysis of infected cells. Dermaseptin derivatives are also able to disrupt the parasite plasma membrane without harming that of the host RBC. PMID:10952593

Krugliak, M; Feder, R; Zolotarev, V Y; Gaidukov, L; Dagan, A; Ginsburg, H; Mor, A

2000-09-01

358

Covariance matrix of derived quantities and their combination.  

National Technical Information Service (NTIS)

The covariance matrix of quantities derived from measured data via nonlinear relations are only approximate since they are functions of the measured data taken as estimates for the true values of the measured quantities. The evaluation of such derived qua...

Z. Zhao F. G. Perey

1992-01-01

359

76 FR 66011 - Modifications of Certain Derivative Contracts; Hearing Cancellation  

Federal Register 2010, 2011, 2012, 2013

...REG-109006-11] RIN 1545-BK13 Modifications of Certain Derivative Contracts; Hearing Cancellation AGENCY: Internal Revenue...nonassigning counterparty when there is an assignment of certain derivative contracts. DATES: The public hearing, originally...

2011-10-25

360

76 FR 51922 - Modifications of Certain Derivative Contracts; Correction  

Federal Register 2010, 2011, 2012, 2013

...REG-109006-11] RIN 1545-BK13 Modifications of Certain Derivative Contracts; Correction AGENCY: Internal Revenue Service...nonassigning counterparty when there is an assignment of certain derivative contracts. It was published in the Federal Register on...

2011-08-19

361

21 CFR 173.110 - Amyloglucosidase derived from Rhizopus niveus.  

Code of Federal Regulations, 2013 CFR

...ADDITIVES PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173.110...derived from Rhizopus niveus. Amyloglucosidase enzyme product, consisting of enzyme derived from Rhizopus niveus, and...

2013-04-01

362

75 FR 63113 - Financial Resources Requirements for Derivatives Clearing Organizations  

Federal Register 2010, 2011, 2012, 2013

...RIN 3038-AC98, 3038-AD02 Financial Resources Requirements for Derivatives Clearing...proposed regulations establish financial resources requirements for derivatives clearing...that they maintain sufficient financial resources to enable them to perform their...

2010-10-14

363

21 CFR 184.1317 - Garlic and its derivatives.  

Code of Federal Regulations, 2013 CFR

...and its derivatives. (a) Garlic is the fresh or dehydrated bulb or cloves obtained from Allium sativum, a genus of the lily family. Its derivatives include essential oils, oleo-resins, and natural extractives obtained from garlic....

2013-04-01

364

A General Derivation of the Conservation Equation for Wave Action.  

National Technical Information Service (NTIS)

The conservation equation for wave action density and the wave Liouville equation are derived for general dispersive, dissipative media. The derivation of the conservation equation follows from a straightforward extension of the WKB method to time varying...

W. M. Manheimer

1975-01-01

365

40 CFR 721.10328 - Salt of polyalkylenepolyamine derivative (generic).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Salt of polyalkylenepolyamine derivative (generic...Specific Chemical Substances § 721.10328 Salt of polyalkylenepolyamine derivative (generic...chemical substance identified generically as salt of polyalkylenepolyamine...

2012-07-01

366

DNA damaging activity of ellagic acid derivatives.  

PubMed

A strain of yeast rendered repair deficient by the conditional expression of the RAD52 locus was used to search for natural products capable of damaging DNA. Four ellagic acid derivatives, namely 3,3'-dimethyl-4'-O-beta-D-glucopyranosyl ellagic acid (1), 3,3',4-trimethyl-4'-O-beta-D-glucopyranosyl ellagic acid (2), 3'-methyl-3,4-O,O-methylidene ellagic acid (3) and 3'-methyl-3,4-O,O-methylidene-4'-O-beta-D-glucopyranosyl ellagic acid (4), were identified by this assay as DNA damaging natural principles from several plants, including Alangium javanicum, Anisophyllea apetala, Crypteronia paniculata, Mouririi sp. and Scholtzia parviflora. Although none of the isolated principles mediated frank strand scission of DNA in vitro, all of them potently inhibited the growth of yeast in the absence of expression of RAD52. PMID:12628683

Xu, Ya-ming; Deng, Jing-Zhen; Ma, Ji; Chen, Shao-Nong; Marshall, Rebekah; Jones, Shannon H; Johnson, Randall K; Hecht, Sidney M

2003-04-01

367

Overview of medically important antifungal azole derivatives.  

PubMed

Fungal infections are a major burden to the health and welfare of modern humans. They range from simply cosmetic, non-life-threatening skin infections to severe, systemic infections that may lead to significant debilitation or death. The selection of chemotherapeutic agents useful for the treatment of fungal infections is small. In this overview, a major chemical group with antifungal activity, the azole derivatives, is examined. Included are historical and state of the art information on the in vitro activity, experimental in vivo activity, mode of action, pharmacokinetics, clinical studies, and uses and adverse reactions of imidazoles currently marketed (clotrimazole, miconazole, econazole, ketoconazole, bifonazole, butoconazole, croconazole, fenticonazole, isoconazole, oxiconazole, sulconazole, and tioconazole) and under development (aliconazole and omoconazole), as well as triazoles currently marketed (terconazole) and under development (fluconazole, itraconazole, vibunazole, alteconazole, and ICI 195,739). PMID:3069196

Fromtling, R A

1988-04-01

368

Novel Therapeutics: NSAIDs, Derivatives, and Phosphodiesterases  

PubMed Central

The chemopreventive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) for colorectal cancer has been well documented. However, long-term use of NSAIDs is precluded owing to potentially fatal toxicities associated with their mechanism of action involving cyclooxygenase (COX) inhibition. But studies have shown that their anticancer activity may be due, in part, to an off-target effect. Cyclic guanosine monophosphate (cGMP) phosphodiesterases (PDEs), which are responsible for negative regulation of cGMP signaling, are an attractive COX-independent target. cGMP signaling is aberrantly suppressed in cancer cells and its activation appears to be sufficient to inhibit tumor cell growth. Chemically modifying sulindac has produced a series of new derivatives that lack COX-inhibitory activity but have improved cGMP PDE inhibitory activity. This approach is proving to be a promising strategy for the discovery of improved agents for the prevention and/or treatment of colorectal cancer.

Tinsley, Heather N.; Piazza, Gary A.

2012-01-01

369

Warped Phenomenology of Higher-Derivative Gravity  

NASA Astrophysics Data System (ADS)

We examine the phenomenological implications at colliders for the existence of higher-derivative gravity terms as extensions to the Randall-Sundrum model. Such terms are expected to arise on rather general grounds, e.g., from string theory. In 5-d, if we demand that the theory be unitary and ghost free, these new contributions to the bulk action are uniquely of the Gauss-Bonnet form. We demonstrate that the usual expectations for the production cross section and detailed properties of graviton Kaluza-Klein resonances and TeV-scale black holes can be substantially altered by existence of these additional contributions. It is shown that measurements at future colliders will be highly sensitive to the presence of such terms.

Rizzo, Thomas G.

2005-01-01

370

Glycerol derivatives and sterols from Sargassum parvivesiculosum.  

PubMed

Five glycerol derivatives (1-5) and three sterols (6-8) were isolated from the EtOH extraction of the brown alga of Sargassum parvivesiculosum. On the basis of spectroscopic methods, their structures were elucidated as 1,3-di-O-[2',2'-di-(p-phenylene) isopropylidene] glycerol (1), (2S)-1-O-heptatriacontanoyl glycerol (2), (2S)-1,2-di-O-palmitoyl-3-O-(6-sulpho-alpha-D-quinovopyranosyl) glycerol (3), (2S)-1-O-palmitoyl glycerol (4), (2S)-1,3-di-(O-palmitoyl)-2-O-octadecanoyl glycerol (5), 24-ethylcholest-5,23Z-dien-3beta,28zeta-diol (6), 24-vinylcholest-5-en-24zeta-hydroperoxy (7), 24-ethylcholest-4,24(28)-dien-3beta-ol (8), respectively. Among them, 1 and 2 were new. PMID:15304997

Qi, Shu-Hua; Zhang, Si; Huang, Jian-She; Xiao, Zhi-Hui; Wu, Jun; Long, Li-Juan

2004-08-01

371

Enzymatic synthesis of cinnamic acid derivatives.  

PubMed

Using Novozym 435 as catalyst, the syntheses of ethyl ferulate (EF) from ferulic acid (4-hydroxy 3-methoxy cinnamic acid) and ethanol, and octyl methoxycinnamate (OMC) from p-methoxycinnamic acid and 2-ethyl hexanol were successfully carried out in this study. A conversion of 87% was obtained within 2 days at 75 degrees C for the synthesis of EF. For the synthesis of OMC at 80 degrees C, 90% conversion can be obtained within 1 day. The use of solvent and high reaction temperature resulted in better conversion for the synthesis of cinnamic acid derivatives. Some cinnamic acid esters could also be obtained with higher conversion and shorter reaction times in comparison to other methods reported in the literature. The enzyme can be reused several times before significant activity loss was observed. PMID:16614896

Lee, Gia-Sheu; Widjaja, Arief; Ju, Yi-Hsu

2006-04-01

372

Unusual structures of lithium terphenyl derivatives  

Microsoft Academic Search

The synthesis, spectroscopic and structural characterization of three new lithium derivatives of terphenyl ligands are reported. These are the mixed lithium alkyl–lithium aryl compound {Li(t-Bu)LiC6H3-2,6-Trip2} (1, Trip=C6H2-2,4,6-i-Pr3), the dilithiated {LiC6H3-2-(C6H3-2-Me-5-t-Bu)-6-(C6H3-2-CH2Li-5-t-Bu)·Et2O}2 (2), and the ether solvated (Et2O)LiC6H3-2,6-(C6H4-4-t-Bu)2 (3). The synthesis of the terphenyl halide precursors for 2 and 3 is also given. The compound 1 resulted from the treatment of 1-IC6H3-2,6-Trip

Ned J Hardman; Brendan Twamley; Matthias Stender; Richard Baldwin; Shirley Hino; Berthold Schiemenz; Susan M Kauzlarich; Philip P Power

2002-01-01

373

Nanostructured YSZ membranes derived from inorganic salts  

NASA Astrophysics Data System (ADS)

The nanostuctured YSZ (Yttria Stabilized Zirconia) membranes on Si(110) substrates are successfully prepared by sol-gel technology derived from inorganic salts ZrOCl2"8H2O, H2C2O4"2H2O and Y(NO3)3"6H2O. By means of controlling the supersaturation and diffusion velocity in solution when the zirconyl oxalate xerogels are repeptized, spherical colloidal paricles with different distributions are obtained. we propose that the peptization of xerogels can be considered as a process of nucleation and growth of colloidal particles. The membranes are preparated by spinning the modified sols on Si(110) substrates. After calcining at 800°C for 1 hour, the membranes are crack-free and mirrorlike. The membranes consist of monodisperse fine spherical crystallines in the range of 20~220nm in diameter, which microstructures are controlled by changing the size and distribution of colloidal particles in sols.

Zhang, Cunlin; Liao, Yang; He, Shuli; Sun, Defeng; Chen, Wen

2005-01-01

374

Integrable discretizations of derivative nonlinear Schrödinger equations  

NASA Astrophysics Data System (ADS)

We propose integrable discretizations of derivative nonlinear Schrödinger (DNLS) equations such as the Kaup-Newell equation, the Chen-Lee-Liu equation and the Gerdjikov-Ivanov equation by constructing Lax pairs. The discrete DNLS systems admit the reduction of complex conjugation between two dependent variables and possess bi-Hamiltonian structure. Through transformations of variables and reductions, we obtain novel integrable discretizations of the nonlinear Schrödinger (NLS), modified KdV (mKdV), mixed NLS, matrix NLS, matrix KdV, matrix mKdV, coupled NLS, coupled Hirota, coupled Sasa-Satsuma and Burgers equations. We also discuss integrable discretizations of the sine-Gordon equation, the massive Thirring model and their generalizations.

Tsuchida, Takayuki

2002-09-01

375

Towards Tartaric-Acid-Derived Asymmetric Organocatalysts  

PubMed Central

Tartaric acid is one of the most prominent naturally occurring chiral compounds. Whereas its application in the production of chiral ligands for metal-catalysed reactions has been exhaustively investigated, its potential to provide new organocatalysts has been less extensively explored. Nevertheless, some impressive results, such as the use of TADDOLs as chiral H-bonding catalysts or of tartrate-derived asymmetric quaternary ammonium salt catalysts, have been reported over the last decade. The goal of this article is to provide a representative overview of the potential and the limitations of tartaric acid or TADDOLs in the creation of new organocatalysts and to highlight some of the most spectacular applications of these catalysts, as well as to summarize case studies in which other classes of chiral backbones were better suited.

Gratzer, Katharina; Gururaja, Guddeangadi N; Waser, Mario

2013-01-01

376

Platelet-Derived Serotonin Mediates Liver Regeneration  

NASA Astrophysics Data System (ADS)

The liver can regenerate its volume after major tissue loss. In a mouse model of liver regeneration, thrombocytopenia, or impaired platelet activity resulted in the failure to initiate cellular proliferation in the liver. Platelets are major carriers of serotonin in the blood. In thrombocytopenic mice, a serotonin agonist reconstituted liver proliferation. The expression of 5-HT2A and 2B subtype serotonin receptors in the liver increased after hepatectomy. Antagonists of 5-HT2A and 2B receptors inhibited liver regeneration. Liver regeneration was also blunted in mice lacking tryptophan hydroxylase 1, which is the rate-limiting enzyme for the synthesis of peripheral serotonin. This failure of regeneration was rescued by reloading serotonin-free platelets with a serotonin precursor molecule. These results suggest that platelet-derived serotonin is involved in the initiation of liver regeneration.

Lesurtel, Mickael; Graf, Rolf; Aleil, Boris; Walther, Diego J.; Tian, Yinghua; Jochum, Wolfram; Gachet, Christian; Bader, Michael; Clavien, Pierre-Alain

2006-04-01

377

Autocrine Effects of Tumor-Derived Complement  

PubMed Central

SUMMARY We describe a role for the complement system in enhancing cancer growth. Cancer cells secrete complement proteins that stimulate tumor growth upon activation. Complement promotes tumor growth via a direct autocrine effect that is partially independent of tumor-infiltrating cytotoxic T cells. Activated C5aR and C3aR signal through the PI3K/AKT pathway in cancer cells, and silencing the PI3K or AKT gene in cancer cells eliminates the progrowth effects of C5aR and C3aR stimulation. In patients with ovarian or lung cancer, higher tumoral C3 or C5aR mRNA levels were associated with decreased overall survival. These data identify a role for tumor-derived complement proteins in promoting tumor growth, and they therefore have substantial clinical and therapeutic implications.

Cho, Min Soon; Vasquez, Hernan G.; Rupaimoole, Rajesha; Pradeep, Sunila; Wu, Sherry; Zand, Behrouz; Han, Hee-Dong; Rodriguez-Aguayo, Cristian; Bottsford-Miller, Justin; Huang, Jie; Miyake, Takahito; Choi, Hyun-Jin; Dalton, Heather J.; Ivan, Cristina; Baggerly, Keith; Lopez-Berestein, Gabriel; Sood, Anil K.; Afshar-Kharghan, Vahid

2014-01-01

378

Derivation of quantum theory from Feynman's rules  

NASA Astrophysics Data System (ADS)

Feynman's formulation of quantum theory is remarkable in its combination of formal simplicity and computational power. However, as a formulation of the abstract structure of quantum theory, it is incomplete as it does not account for most of the fundamental mathematical structure of the standard von Neumann-Dirac formalism such as the unitary evolution of quantum states. In this paper, we show how to reconstruct the entirety of the finite-dimensional quantum formalism starting from Feynman's rules with the aid of a single physical postulate, the no-disturbance postulate. This postulate states that a particular class of measurements have no effect on the outcome probabilities of subsequent measurements performed. We also show how it is possible to derive both the amplitude rule for composite systems of distinguishable subsystems and Dirac's amplitude-action rule, each from a single elementary and natural assumption, by making use of the fact that these assumptions must be consistent with Feynman's rules.

Goyal, Philip

2014-03-01

379

Autocrine effects of tumor-derived complement.  

PubMed

We describe a role for the complement system in enhancing cancer growth. Cancer cells secrete complement proteins that stimulate tumor growth upon activation. Complement promotes tumor growth via a direct autocrine effect that is partially independent of tumor-infiltrating cytotoxic T cells. Activated C5aR and C3aR signal through the PI3K/AKT pathway in cancer cells, and silencing the PI3K or AKT gene in cancer cells eliminates the progrowth effects of C5aR and C3aR stimulation. In patients with ovarian or lung cancer, higher tumoral C3 or C5aR mRNA levels were associated with decreased overall survival. These data identify a role for tumor-derived complement proteins in promoting tumor growth, and they therefore have substantial clinical and therapeutic implications. PMID:24613353

Cho, Min Soon; Vasquez, Hernan G; Rupaimoole, Rajesha; Pradeep, Sunila; Wu, Sherry; Zand, Behrouz; Han, Hee-Dong; Rodriguez-Aguayo, Cristian; Bottsford-Miller, Justin; Huang, Jie; Miyake, Takahito; Choi, Hyun-Jin; Dalton, Heather J; Ivan, Cristina; Baggerly, Keith; Lopez-Berestein, Gabriel; Sood, Anil K; Afshar-Kharghan, Vahid

2014-03-27

380

Overview of medically important antifungal azole derivatives.  

PubMed Central

Fungal infections are a major burden to the health and welfare of modern humans. They range from simply cosmetic, non-life-threatening skin infections to severe, systemic infections that may lead to significant debilitation or death. The selection of chemotherapeutic agents useful for the treatment of fungal infections is small. In this overview, a major chemical group with antifungal activity, the azole derivatives, is examined. Included are historical and state of the art information on the in vitro activity, experimental in vivo activity, mode of action, pharmacokinetics, clinical studies, and uses and adverse reactions of imidazoles currently marketed (clotrimazole, miconazole, econazole, ketoconazole, bifonazole, butoconazole, croconazole, fenticonazole, isoconazole, oxiconazole, sulconazole, and tioconazole) and under development (aliconazole and omoconazole), as well as triazoles currently marketed (terconazole) and under development (fluconazole, itraconazole, vibunazole, alteconazole, and ICI 195,739).

Fromtling, R A

1988-01-01

381

Antioxidant and antifungal properties of benzimidazole derivatives.  

PubMed

Antioxidant and radical scavenging properties of a series of 2-[4-(substituted piperazin-/piperidin-1-ylcarbonyl)phenyl]-1H-benzimidazole derivatives were examined. Free radical scavenging properties of compounds 11-30 and 33 were evaluated for the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide anion radical. In addition the inhibitory effects on the NADPH-dependent lipid peroxidation levels were determined by measuring the formation of 2-thiobarbituric acid reactive substances (TBARS) using rat liver microsomes. Compound 33 which has a p-fluorobenzyl substitutent at position 1 exhibited the strongest inhibition (83%) of lipid peroxidation at a concentration of 10(-3) M, while the nonsubstituted analogue 13 caused 57% inhibition. This result is fairly consistent with the antimicrobial activity results against both Staphylococcus aureus and Candida albicans. PMID:21138053

Ku?, Canan; Sözüdönmez, Fatma; Can-Eke, Benay; Coban, Tülay

2010-01-01

382

Calixradialenes: calixarene derivatives with exocyclic double bonds.  

PubMed

Reaction of dioxocalix[4]arene 7 with MeLi followed by 2-fold elimination of water yielded calixarene 8 possessing exocyclic double bonds at two adjacent bridges. Calixarene 8 exists in tetrachloroethane-d2 solution at rt, as a 2.3:1 mixture of the 1,3-alternate and partial cone conformers. Keto[n]calixarenes (n = 5, 6) were prepared via hydrolysis of the bromocalixarenes 11 and 12, followed by CrO3 oxidation of the respective hydroxymethylene derivatives. Addition of MeLi to the ketocalix[n]arenes (n = 4, 5 and 6) followed by elimination of water yielded the corresponding calix[n]radialenes. Calix[5]- and calix[6]radialenes adopt in the crystal irregular alternate (i.e., noncone) conformations. PMID:24364562

Poms, David; Itzhak, Norbert; Kuno, Lev; Biali, Silvio E

2014-01-17

383

Thalidomide derivatives for the treatment of neuroinflammation.  

PubMed

The precise mechanism-of-action of thalidomide remains uncertain and might differ between diseases and under different clinical condition. With implications in the treatment of a variety of inflammatory and autoimmune diseases, as well as for use as an anticancer agent, alone or in combination with established therapeutics, it is clear that thalidomide and its derivatives deserve further scrutiny. In particular, thalidomide was shown to be effective in a mouse model of multiple sclerosis (MS), an autoimmune inflammatory disorder, called experimental autoimmune encephalomyelitis (EAE). Herein, we describe the synthesis and preliminary biological evaluation of new macromolecular prodrugs of thalidomide bearing an aminoalkyl group on the phthalimide ring. The effectiveness of these compounds to limit EAE was investigated, and it was shown that, at 100?mg?kg?¹ thalidomide-equivalent dose, they abrogated the clinical and pathological features of EAE. PMID:20936622

Contino-Pépin, Christiane; Parat, Audrey; Patinote, Cindy; Roscoe, Wendi A; Karlik, Stephen J; Pucci, Bernard

2010-12-01

384

[Effect of piracetam derivatives on antibody formation].  

PubMed

Immunomodulatory effects of piracetam and a number of its derivatives were studied in mice. It was shown that multiple injections of such substances at a dose of 50-200 mg/kg change the amount of antibody-forming cells in the spleen of animals immunized with sheep red blood cells. The dose of 200 mg/kg was the most effective one, with the direction of immunomodulatory activity depending on the chemical composition of the compounds. Thus joining of phenol radical to piracetam molecule strengthened immunosuppression, and vice versa insertion of hydrazide group led to stimulation of antibody formation. It is stressed that immunosuppressive effect of piracetam must be taken into consideration during the clinical use of the drug. PMID:4063506

Ratnikov, V I; Ostrovskaia, R U; Vazhenina, Z P; Skoldinov, A P

1985-11-01

385

Carbide-derived-carbon-based oxygen carriers  

US Patent & Trademark Office Database

An oxygen delivery system is disclosed. The basis of the oxygen deliver system is a carbide-derived carbon (CDC). The CDC can be tuned to carry O.sub.2 directly (CDC OC), or hemoglobin can be adsorbed to provide a hemoglobin-based oxygen carrier (CDC HBOC). The delivery system allows the use of a variety of hemoglobins which differ in their oxygen dissociation profiles, including variant and mutant hemoglobins from other species. The delivery system is biocompatible and stable, and is able to irreversibly bind and hold large amounts of functional hemoglobin variants. The CDC HBOC and CDC OC provide a safe and effective blood substitute for combat casualty care, as well as being useful for oxygen delivery in other contexts.

2014-04-15

386

Uncertainties in derived temperature-height profiles  

NASA Technical Reports Server (NTRS)

Nomographs were developed for relating uncertainty in temperature T to uncertainty in the observed height profiles of both pressure p and density rho. The relative uncertainty delta T/T is seen to depend not only upon the relative uncertainties delta P/P or delta rho/rho, and to a small extent upon the value of T or H, but primarily upon the sampling-height increment Delta h, the height increment between successive observations of p or delta. For a fixed value of delta p/p, the value of delta T/T varies inversely with Delta h. No limit exists in the fineness of usable height resolution of T which may be derived from densities, while a fine height resolution in pressure-height data leads to temperatures with unacceptably large uncertainties.

Minzner, R. A.

1974-01-01

387

Furanone derivatives from terrestrial Streptomyces spp.  

PubMed

Chemical investigation of the terrestrial Streptomyces sp. isolates GT2005/020 and ANK148 led to the isolation of two microbial furanone derivatives, 5-hydroxy-4-methylnaphtho[1,2-b]furan-3-one (1) and 4-hydroxy-5-methyl-furan-3-one (2), respectively, which have some similarity to quorum sensing molecules of the AI-2 type. In addition, the known compounds chalcomycin, ferulic acid, indole-3-acetic acid, uracil, thymine, 2'-deoxy-thymidin, monensin B (3), phencomycin, and 1-acetyl-beta-carboline were isolated. The structures of 1 and 2 were deduced from extensive studies of NMR (1D and 2D) and mass spectra. Additionally, the complete NMR shift assignments for monensin B (3) using H-H COSY, HMQC and HMBC experiments are reported here for the first time. We are describing the taxonomy and fermentation of the producing strains, the structure elucidation of the new metabolites and their bioactivity. PMID:23074908

Arfan, Muhammad; Shaaban, Khaled A; Schüffler, Anja; Laatsch, Hartmut

2012-09-01

388

Satellite derived cirrus particle size - Tropical clouds  

NASA Technical Reports Server (NTRS)

The present study extends the earlier work of Wielicki et al. (1990) to examine several cases of tropical cirrus clouds. Particle effective radius is estimated and compared to other studies of cirrus clouds. Particle size and phase are estimated by comparing reflectance observations by the Landsat satellite with theoretical calculations for a range of possible water and ice particle sizes. An examination of effective particle radius for six cases of tropical cirrus clouds over the eastern Pacific Ocean found typical radii of 60 microns. This value is similar to that derived for a case of midlatitude cirrus during the FIRE experiment in October 1986. Particle size is found to increase with decreasing cloud optical depth.

Wielicki, Bruce A.; Suttles, John T.; Parker, Lindsay; Arduini, Robert F.

1990-01-01

389

Lie Triple Derivations of CSL Algebras  

NASA Astrophysics Data System (ADS)

Let [InlineEquation not available: see fulltext.] be a commutative subspace lattice generated by finite many commuting independent nests on a complex separable Hilbert space [InlineEquation not available: see fulltext.] with [InlineEquation not available: see fulltext.], and [InlineEquation not available: see fulltext.] the associated CSL algebra. It is proved that every Lie triple derivation from [InlineEquation not available: see fulltext.] into any ?-weakly closed algebra [InlineEquation not available: see fulltext.] containing [InlineEquation not available: see fulltext.] is of the form X? XT- TX+ h( X) I, where [InlineEquation not available: see fulltext.] and h is a linear mapping from [InlineEquation not available: see fulltext.] into ? such that h([[ A, B], C])=0 for all [InlineEquation not available: see fulltext.].

Yu, Weiyan; Zhang, Jianhua

2013-06-01

390

[Epilepsy and pseudoseizures derived from their dissociation].  

PubMed

Many epileptic patients have pseudoseizures (psychogenic nonepileptic seizures mimicking epileptic seizures) derived from their dissociation (conversion) or other psychiatric symptoms. The pseudoseizure cast many problems on medical support for their management. In this article I reported the result of investigation of pseudoseizures in an epilepsy unit in department of psychiatry, National Center Hospital for Mental, Nervous, and Muscular Disorders, National Center of Neurology and Psychiatry. And I reffered to treatment and prognosis of pseudoseizures. The key points for psychiatrists in treating epileptic patients having pseudoseizures were; 1) not to hesitate to consult with specialists about diagnosis, 2) to distinguish a pseudoseizure from an epileptic seizure and to treat them separately, 3) not to treat seizure phenomena but patients by keeping reliable relationship with them. PMID:16637587

Kato, Masaaki

2006-01-01

391

Fluorescein Derivatives in Intravital Fluorescence Imaging  

PubMed Central

Intravital fluorescence microscopy enables the direct imaging of fluorophores in vivo and advanced techniques such as fluorescence lifetime imaging (FLIM) enable the simultaneous detection of multiple fluorophores. Consequently, it is now possible to record distribution and metabolism of a chemical in vivo and to optimise the delivery of fluorophores in vivo. Recent clinical applications with fluorescein and other intravital fluorescent stains have occurred in neurosurgery, dermatology [including photodynamic therapy (PDT)] and endomicroscopy. Potential uses have been identified in periodontal disease, skin graft and cancer surgery. Animal studies have demonstrated that diseased tissue can be specifically stained with fluorophore conjugates. This review focuses on the fluorescein derived fluorophores in common clinical use and provides examples of novel applications from studies in tissue samples.

Robertson, Thomas A.; Bunel, Florestan; Roberts, Michael S.

2013-01-01

392

Higher derivative corrections in holographic QCD  

SciTech Connect

We consider the effect of the R{sup 4} term in type IIA string theory on the supergravity background dual to N{sub c} D4-branes compactified on a circle with supersymmetry breaking boundary conditions. We study the dynamics of D8-branes in this perturbed geometry in the probe approximation. This leads to an analysis of higher derivative corrections in holographic QCD beyond the supergravity approximation. We make a rough estimate of the corrections to the masses of some of the lightest (axial) vector mesons. The corrections are suppressed by a factor of (g{sub YM}{sup 2}N{sub c}){sup -3} compared to their supergravity values. We find that the masses of these mesons increase from their supergravity values.

Basu, Anirban [Institute for Advanced Study, Princeton, New Jersey 08540 (United States)

2007-12-15

393

Inhibition of mycobacterial growth by plumbagin derivatives.  

PubMed

Electron transport and respiratory pathways are active in both latent and rapidly growing mycobacteria and remain conserved in all mycobacterial species. In mycobacteria, menaquinone is the sole electron carrier responsible for electron transport. Menaquinone biosynthesis pathway is found to be essential for the growth of mycobacteria. Structural analogs of the substrate or product of this pathway are found to be inhibitory for the growth of Mycobacterium smegmatis and M. tuberculosis. Several plumbagin [5-hydroxy-2-methyl-1, 4-naphthaquinone] derivatives have been analyzed for their inhibitory effects of which butyrate plumbagin was found to be most effective on M. smegmatis mc(2)155, whereas crotonate plumbagin showed greater activity on M. tuberculosis H37Rv. Effect on electron transport and respiration was demonstrated by butyrate plumbagin inhibiting oxygen consumption in M. smegmatis. Structural modifications of these molecules can further be improved upon to generate new molecules against mycobacteria. PMID:20456370

Mathew, Ritta; Kruthiventi, Anil K; Prasad, Jalli V; Kumar, Sadula P; Srinu, Garlapati; Chatterji, Dipankar

2010-07-01

394

Radiation Protection Using Carbon Nanotube Derivatives  

NASA Technical Reports Server (NTRS)

BHA and BHT are well-known food preservatives that are excellent radical scavengers. These compounds, attached to single-walled carbon nanotubes (SWNTs), could serve as excellent radical traps. The amino-BHT groups can be associated with SWNTs that have carbolyxic acid groups via acid-base association or via covalent association. The material can be used as a means of radiation protection or cellular stress mitigation via a sequence of quenching radical species using nano-engineered scaffolds of SWNTs and their derivatives. It works by reducing the number of free radicals within or nearby a cell, tissue, organ, or living organism. This reduces the risk of damage to DNA and other cellular components that can lead to chronic and/or acute pathologies, including (but not limited to) cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. These derivatives can show an unusually high scavenging ability, which could prove efficacious in protecting living systems from radical-induced decay. This technique could be used to protect healthy cells in a living biological system from the effects of radiation therapy. It could also be used as a prophylactic or antidote for radiation exposure due to accidental, terrorist, or wartime use of radiation- containing weapons; high-altitude or space travel (where radiation exposure is generally higher than desired); or in any scenario where exposure to radiation is expected or anticipated. This invention s ultimate use will be dependent on the utility in an overall biological system where many levels of toxicity have to be evaluated. This can only be assessed at a later stage. In vitro toxicity will first be assessed, followed by in vivo non-mammalian screening in zebra fish for toxicity and therapeutic efficacy.

Conyers, Jodie L., Jr.; Moore, Valerie C.; Casscells, S. Ward

2010-01-01

395

Fluoride removal performance of glass derived hydroxyapatite  

SciTech Connect

Research highlights: {yields} Novel sodium calcium borate glass derived hydroxyapatite (G-HAP) is prepared. {yields} Micro-G-HAP adsorbs F{sup -} ions in solutions more effectively than commercial nano-HAP. {yields} The adsorption kinetics and isotherms are well fitted by a second order kinetic model and Freundlich isotherm model. -- Abstract: A novel sodium calcium borate glass derived hydroxyapatite (G-HAP) with different ranges of particle size was prepared by immersion sodium calcium borate glass in 0.1 M K{sub 2}HPO{sub 4} solution by the ratio of 50 g L{sup -1} for 7 days. The unique advantage of G-HAP for the adsorption of fluoride ions in solutions was studied. The effects of size and quantity of particles, pH value and adsorption time on adsorption performance were investigated. The maximum adsorption capacity was 17.34 mg g{sup -1} if 5 g L{sup -1}, <100 {mu}m G-HAP was added to a solution with an initial pH value of 6.72 and the adsorption time was 12 h. The results showed that the micro-G-HAP could immobilize F{sup -} in solution more effectively than commercial nano-HAP, which makes potential application of the G-HAP in removing the fluoride ions from wastewater. The adsorption kinetics and isotherms for F{sup -} could be well fitted by a second order kinetic model and Freundlich isotherm model respectively, which could be used to describe the adsorption behavior. The mechanism of G-HAP in immobilizing F{sup -} from aqueous solutions was investigated by the X-ray diffraction (XRD), infrared spectra (IR) and scanning electron microscopy (SEM).

Liang, Wen, E-mail: wliang@ecust.edu.cn [Research Institute of Biomaterials, School of Materials Science and Engineering, East China University of Science and Technology (China)] [Research Institute of Biomaterials, School of Materials Science and Engineering, East China University of Science and Technology (China); Zhan, Lei; Piao, Longhua [Research Institute of Biomaterials, School of Materials Science and Engineering, East China University of Science and Technology (China)] [Research Institute of Biomaterials, School of Materials Science and Engineering, East China University of Science and Technology (China); Russel, Christian [Otto-Schott-Institut, Universitaet Jena, Jena (Germany)] [Otto-Schott-Institut, Universitaet Jena, Jena (Germany)

2011-02-15

396

Dispersant using kraft lignin and novel lignin derivative  

US Patent & Trademark Office Database

The dispersant of the present invention comprises at least one component unit derived from kraft lignin and/or its salt and at least one component unit derived from at least one water-soluble monomer. The novel lignin derivative of the present invention comprises at least one component unit derived from kraft lignin and/or its salt, at least one polyoxyalkylene chain, and at least one anionic functional group.

2010-04-06

397

Optimum sensitivity derivatives of objective functions in nonlinear programming  

NASA Technical Reports Server (NTRS)

The feasibility of eliminating second derivatives from the input of optimum sensitivity analyses of optimization problems is demonstrated. This elimination restricts the sensitivity analysis to the first-order sensitivity derivatives of the objective function. It is also shown that when a complete first-order sensitivity analysis is performed, second-order sensitivity derivatives of the objective function are available at little additional cost. An expression is derived whose application to linear programming is presented.

Barthelemy, J.-F. M.; Sobieszczanski-Sobieski, J.

1983-01-01

398

Alternative derivation of the response of interferometric gravitational wave detectors  

SciTech Connect

It has recently been pointed out by Finn that the long-standing derivation of the response of an interferometric gravitational wave detector contains several errors. Here I point out that a contemporaneous derivation of the gravitational wave response for spacecraft doppler tracking and pulsar timing avoids these pitfalls, and when adapted to describe interferometers, recovers a simplified version of Finn's derivation. This simplified derivation may be useful for pedagogical purposes.

Cornish, Neil J. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States)

2009-10-15

399

Immunological equivalence between mouse brain-derived and Vero cell-derived Japanese encephalitis vaccines.  

PubMed

The persistent spread via animal reservoirs urges expanding vaccination programs against pathogens like the Japanese encephalitis virus, JEV. The JEV is spreads to new areas by domestic as well as by wild animals. Although there is a safe and efficient vaccine on the market, this is derived from infected mouse brains, why today's situation requires overcoming the potential risk caused by using animal tissues. To meet this demand we have developed a Vero cell-derived JEV vaccine, using the same virus strain as in the established one. A phase III clinical study of the new vaccine has recently been completed with positive outcome. Like the established mouse brain-derived vaccine, the Vero cell-derived one is a formalin inactivated whole virus vaccine. We here demonstrate the very good agreement in immunological tests between the two antigens. The study includes analyses with two neutralizing monoclonal antibodies that blocks cell entry at a late stage in infection, assumedly interfering with fusion-related refolding in the virus fusion protein. It is obvious that the formalin inactivation treatment, with both virus preparations, retains these essential vaccine epitopes. PMID:16815584

Abe, Motoharu; Shiosaki, Kouichi; Hammar, Lena; Sonoda, Kengo; Xing, Li; Kuzuhara, Syoji; Kino, Yoichiro; Holland Cheng, R

2006-11-01

400

AVHRR compatible vegetation index derived from MERIS data  

Microsoft Academic Search

The Advanced Very High Resolution Radiometer (AVHRR) compatible vegetation index derived from data of the MEdium Resolution Imaging Spectrometer (MERIS) is regarded as a continuity index for the well known Normalized Difference Vegetation Index (NDVI) derived from AVHRR with 300 meter resolution. For deriving the AVHRR compatible vegetation index MERIS full resolution (FR) top of atmosphere radiances (ESA L1b data)

K. P. Günther; S. W. Maier

2007-01-01

401

Buckytubes and Derivatives: Their Growth and Implications for Buckyball Formation  

Microsoft Academic Search

Transmission electron microscopy (TEM) observations of graphite tubules (buckytubes) and their derivatives have revealed not only the previously reported buckytube geometries but also additional shapes of the buckytube derivatives. Detailed cross-sectional TEM images reveal the cylindrical cross section of buckytubes and the growth pattern of buckytubes as well as their derivatives. These observations of frozen growth stages of buckytubes and

V. P. Dravid; X. Lin; Y. Wang; X. K. Wang; A. Yee; J. B. Ketterson; R. P. H. Chang

1993-01-01

402

Derivation of aircraft, linear state equations from implicit nonlinear equations  

Microsoft Academic Search

The classical approach to deriving linear models of aircraft dynamics is cumbersome because of the lack of a formal algebraic framework. A new point of view is taken to provide a streamlined derivation for the linear state equations by using some formal mathematical tools. These tools include matrix calculus and implicit differential equations. The linear equations derived differ slightly from

B. L. Stevens

1990-01-01

403

Kinetic Theory Derivation of the Adiabatic Law for Ideal Gases.  

ERIC Educational Resources Information Center

Discusses how the adiabatic law for ideal gases can be derived from the assumption of a Maxwell-Boltzmann (or any other) distribution of velocities--in contrast to the usual derivations from thermodynamics alone, and the higher-order effect that leads to one-body viscosity. An elementary derivation of the adiabatic law is given. (Author/DS)

Sobel, Michael I.

1980-01-01

404

40 CFR 721.10317 - Alkyl phosphate derivative (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Alkyl phosphate derivative (generic). 721.10317...Chemical Substances § 721.10317 Alkyl phosphate derivative (generic). (a) Chemical...substance identified generically as alkyl phosphate derivative (PMN P-02-1040)...

2013-07-01

405

Triterpene Derivatives that Inhibit Human Immunodeficiency Virus Type 1 Replication  

PubMed Central

Triterpene derivatives were analyzed for anti-HIV-1 activity and for cellular toxicity. Betulinic aldehyde, betulinic nitrile, and morolic acid derivatives were identified to have anti-HIV-1 activity. These derivatives inhibit a late step in virus replication, likely virus maturation.

Dorr, Casey R.; Yemets, Sergiy; Kolomitsyna, Oksana; Krasutsky, Pavel; Mansky, Louis M.

2010-01-01

406

Triterpene derivatives that inhibit human immunodeficiency virus type 1 replication.  

PubMed

Triterpene derivatives were analyzed for anti-HIV-1 activity and for cellular toxicity. Betulinic aldehyde, betulinic nitrile, and morolic acid derivatives were identified to have anti-HIV-1 activity. These derivatives inhibit a late step in virus replication, likely virus maturation. PMID:21084190

Dorr, Casey R; Yemets, Sergiy; Kolomitsyna, Oksana; Krasutsky, Pavel; Mansky, Louis M

2011-01-01

407

A note on computing the derivative at a constant direction  

Microsoft Academic Search

The derivative at constant direction is frequently used in inversion of cone-beam data. Several algorithms for computing the derivative have been proposed in the literature. The best algorithm to date has been proposed recently by Noo et al (2007 Phys. Med. Biol. 52 5393-414). In this note we propose a new, simple and efficient formula for computing the derivative. Numerical

A. Katsevich

2011-01-01

408

Synthesis and acetylcholinesterase inhibition of 5-desamino huperzine A derivatives  

Microsoft Academic Search

(E)- and (Z)-5-Desamino huperzine A derivatives have been synthesized using a new synthetic strategy towards the huperzine A skeleton. These derivatives showed AChE inhibition constants in the low micromolar range and thus display better activity than all previously synthesized C5 derivatives.

Klemens Högenauer; Karl Baumann; Albert Enz; Johann Mulzer

2001-01-01

409

Synthesis and acetylcholinesterase inhibition of 5-desamino huperzine A derivatives.  

PubMed

(E)- and (Z)-5-Desamino huperzine A derivatives have been synthesized using a new synthetic strategy towards the huperzine A skeleton. These derivatives showed AChE inhibition constants in the low micromolar range and thus display better activity than all previously synthesized C5 derivatives. PMID:11551765

Högenauer, K; Baumann, K; Enz, A; Mulzer, J

2001-10-01

410

Updating Derived Relations: Detecting Irrelevant and Autonomously Computable Updates  

Microsoft Academic Search

Consider a database containing not only base rela- tions but also stored derived relations (also called materialized or concrete views). When a base rela- tion is updated, it may also be necessary to update some of the derived relations. This paper gives suf- ficient and necessary conditions for detecting when an update of a base relation cannot affect a derived

José A. Blakeley; Neil Coburn; Per-åke Larson

1986-01-01

411

Boolean Derivatives With Application to Edge Detection for Imaging Systems  

Microsoft Academic Search

This paper introduces a new concept of Boolean derivatives as a fusion of partial derivatives of Boolean functions (PDBFs). Three efficient algorithms for the calculation of PDBFs are presented. It is shown that Boolean function derivatives are useful for the application of identifying the location of edge pixels in binary images. The same concept is extended to the development of

Sos S. Agaian; Karen A. Panetta; Shahan C. Nercessian; Ethan E. Danahy

2010-01-01

412

Synthesis of Kojic Acid Derivatives Containing Phenolic Hydroxy Groups  

Microsoft Academic Search

Two kojic acid derivatives (2a and 2b) containing phenolic hydroxy groups were synthesized. The preparation was carried out by the reaction of a kojic acid derivative (3) having a chloromethyl group with phenol derivatives (4 and 7), followed by the subsequent deprotection steps. The first reaction proceeded smoothly in the presence of potassium carbonate in DMF at room temperature. Then,

J. Kadokawa; T. Nishikura; R. Muraoka; H. Tagaya; N. Fukuoka

2003-01-01

413

Marchenko Equation for the Derivative Nonlinear Schrödinger Equation  

NASA Astrophysics Data System (ADS)

A simple derivation of the Marchenko equation is given for the derivative nonlinear Schrödinger equation. The kernel of the Marchenko equation is demanded to satisfy the conditions given by the compatibility equations. The soliton solutions to the Marchenko equation are verified. The derivation is not concerned with the revisions of Kaup and Newell.

Huang, Nian-Ning

2007-04-01

414

Thymol derivatives from hairy roots of Arnica montana  

Microsoft Academic Search

Five known thymol derivatives were isolated from roots of Arnica montana transformed with Agrobacterium rhizogenes LBA 9402. The compounds were characterized by spectral methods. The pattern of thymol derivatives in light-grown hairy roots was slightly different from that in dark-grown ones. This is the first report on the presence of thymol derivatives in hairy roots of the plant.

I. Weremczuk-Je?yna; W. Kisiel; H. Wysoki?ska

2006-01-01

415

Derivation of low flow distribution functions using copulas  

NASA Astrophysics Data System (ADS)

The method of deriving copula-based low flow distributions is proposed.Statistical dependence is detected among the characteristics of low flow event.Copula-based derived distributions can perform well against observations.Choice of marginal distributions is important in copula-based derived distribution.It is useful to study the impacts of climate change/human activities on low flows.

Yu, Kun-xia; Xiong, Lihua; Gottschalk, Lars

2014-01-01

416

Thermodynamic Derivation of the Equilibrium Distribution Functions of Statistical Mechanics.  

ERIC Educational Resources Information Center

Presents a simplified derivation of the equilibrium distribution functions. The derivation proceeds from the change in the Helmholtz free energy when a particle is added to a system of fixed temperature, volume, and chemical potential. The derivations show the relationship between statistical mechanics and macroscopic thermodynamics. (Author/GA)

Stoeckly, Beth

1979-01-01

417

Pricing Derivatives on Financial Securities Subject to Credit Risk  

Microsoft Academic Search

This article provides a new methodology for pricing and hedging derivative securities involving credit risk. Two types of credit risks are considered. The first is where the asset underlying the derivative security may default. The second is where the writer of the derivative security may default. The authors apply the foreign currency analogy of R. Jarrow and S. Turnbull (1991)

Robert A. Jarrow; Stuart M. Turnbull

1995-01-01

418

No violation of the Leibniz rule. No fractional derivative  

NASA Astrophysics Data System (ADS)

We demonstrate that a violation of the Leibniz rule is a characteristic property of derivatives of non-integer orders. We prove that all fractional derivatives D?, which satisfy the Leibniz rule D?(fg)=(D?f)g+f(D?g), should have the integer order ?=1, i.e. fractional derivatives of non-integer orders cannot satisfy the Leibniz rule.

Tarasov, Vasily E.

2013-11-01

419

Characterizing Thematized Derivative Schema by the Underlying Emergent Structures  

ERIC Educational Resources Information Center

This paper reports on different underlying structures of the derivative schema of three undergraduate students that were considered to be at the trans level of development of the derivative schema (action-process-object-schema). The derivative schema is characterized in terms of the students' ability to explicitly transfer the relationship between…

Garcia, Mercedes; Llinares, Salvador; Sanchez-Matamoros, Gloria

2011-01-01

420

Epimeric methylsulfinyladenosine derivatives from the marine ascidian Herdmania momus.  

PubMed

Investigation of the secondary metabolites of the ascidian Herdmania momus led to the isolation and characterization of four new nucleoside derivatives (1-4). Structural studies showed that these derivatives represent a series of rare methylsulfinyladenosine derivatives of interconvertible transesterification isomers and/or sulfinyl epimers. The antiviral activities of these rare nucleosides were evaluated against a series of human pathogenic viruses. PMID:23810281

Li, Jian Lin; Kim, Eun La; Wang, Haibo; Hong, Jongki; Shin, Sook; Lee, Chong-Kyo; Jung, Jee H

2013-08-15

421

The Derivation of Meaning in the Navajo Verb.  

ERIC Educational Resources Information Center

Lexical derivation in the Navajo verb system is described, with examples. Derivation involves four broad processes: (1) straightforward use of verbal roots and adverbial-derivational prefixes, with their base meanings; (2) extension of base root meaning, often by metaphor, to permit application to disparate concepts; (3) figurative use of…

Young, Robert W.

422

Evaluation of Importance of Lateral Acceleration Derivatives in Extraction of Lateral-Directional Derivatives at High Angles of Attack.  

National Technical Information Service (NTIS)

A theoretical investigation was conducted to determine the importance of the lateral acceleration (beta) derivatives in the extraction of lateral-directional stability derivatives for swept wing airplanes at high angles of attack. Representative values of...

L. T. Nguyen

1974-01-01

423

Design principles for an interactive program derivation system  

NASA Technical Reports Server (NTRS)

The main design principles of an interactive program transformation system called FOCUS are outlined. Its important characteristics are its human-oriented deduction techniques based replacement, emphasis on small search spaces, and the use of a tree structure to organize program derivations. The tree structure presents to the user a static picture of the derivation process and promotes flexibility in the development of derivations. The system keeps track of dependencies between different parts of derivations, and records the derivation activity for later use in automatic replay.

Reddy, Uday S.

1988-01-01

424

Polyketides from a Marine-Derived Fungus Xylariaceae sp.  

PubMed Central

Eighteen polyketides (1–18) including six citrinin derivatives, two phenol derivatives, one cyclopentenone, two naphthol derivatives, and seven tetralone derivatives were isolated from the culture broth of a marine-derived fungal strain Xylariaceae sp. SCSGAF0086. Five of these compounds (1, 2, 8, 9, and 10) were new, and their structures were determined by spectroscopic methods. Compounds 4, 6, 7, and 17 showed enzyme-inhibitory activities towards several tested enzymes, and 6 and 7 showed strong antifouling activity against Bugula neritina larvae settlement. This is the first time that the antifouling and enzyme-inhibitory activities of these compounds has been reported.

Nong, Xu-Hua; Zheng, Zhi-Hui; Zhang, Xiao-Yong; Lu, Xin-Hua; Qi, Shu-Hua

2013-01-01

425

Effects of sulfate chitosan derivatives on nonalcoholic fatty liver disease  

NASA Astrophysics Data System (ADS)

Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentration emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly ameliorated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-? in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD.

Yu, Mingming; Wang, Yuanhong; Jiang, Tingfu; Lv, Zhihua

2014-06-01

426

Structural characteristics of dibromoborylated benzene derivatives.  

PubMed

The crystal structures of five dibromobenzene derivatives, namely dibromoborylbenzene, C(6)H(5)BBr(2), (I), 1-dibromoboryl-4-(trimethylsilyl)benzene, C(9)H(13)BBr(2)Si, (II), 4-bromo-1-(dibromoboryl)benzene, C(6)H(4)BBr(3), (III), dibromo(dimethylamino)(phenyl)borane, C(8)H(12)BBr(2)N, (IV), and dibromo(dimethylsulfanyl)[4-(trimethylsilyl)phenyl]borane, C(11)H(19)BBr(2)SSi, (V), have been determined. Compounds (I)-(IV) crystallize with one molecule in the asymmetric unit, but the molecule of (V) is located on a crystallographic mirror plane, implying twofold disorder of the central aromatic ring, the S atom and one of the methyl groups bonded to the S atom. In (I), (II) and (III), the B atom is three-coordinated, and in (IV) and (V) it is four-coordinated. The geometric parameters of the -BBr(2) group in these five structures agree well with those of comparable structures retrieved from the Cambridge Structural Database. The C-B and B-Br bond lengths in the molecules with a three-coordinated B atom are significantly shorter than those in the molecules with a four-coordinated B atom. In the compounds with a three-coordinated B atom, the -BBr(2) group tends to be coplanar with the aromatic ring to which it is attached. PMID:22669193

Popp, Sebastian; Ruth, Kai; Lerner, Hans-Wolfram; Bolte, Michael

2012-06-01

427

Amino acids derived from Titan tholins  

NASA Technical Reports Server (NTRS)

An organic heteropolymer (Titan tholin) was produced by continuous dc discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mbar pressure, roughly simulating the cloudtop atmosphere of Titan. Treatment of this tholin with 6N HCl yielded 16 amino acids by gas chromatography after derivatization of N-trifluroacetyl isopropyl esters on two different capillary columns. Identifications were confirmed by GC/MS. Glycine, aspartic acid, and alpha- and beta-alanine were produced in greatest abundance; the total yield of amino acids was approximately 10(-2), approximately equal to the yield of urea. The presence of "nonbiological" amino acids, the absence of serine, and the fact that the amino acids are racemic within experimental error together indicate that these molecules are not due to microbial or other contamination, but are derived from the tholin. In addition to the HCN, HC2CN, and (CN)2 found by Voyager, nitriles and aminonitriles should be sought in the Titanian atmosphere and, eventually, amino acids on the surface. These results suggest that episodes of liquid water in the past or future of Titan might lead to major further steps in prebiological organic chemistry on that body.

Khare, B. N.; Sagan, C.; Ogino, H.; Nagy, B.; Er, C.; Schram, K. H.; Arakawa, E. T.

1986-01-01

428

Chitosan derivatives as biosorbents for basic dyes.  

PubMed

The scope of this study was to prepare and evaluate chitosan derivatives as biosorbents for basic dyes. This was achieved by grafting poly (acrylic acid) and poly (acrylamide) through persulfate induced free radical initiated polymerization processes and covalent cross-linking of the prepared materials. Remacryl Red TGL was used as the cationic dye. Equilibrium sorption experiments were carried out at different pH and initial dye concentration values. The experimental equilibrium data for each adsorbent-dye system were successfully fitted to the Langmuir, Freundlich and pH-dependent Langmuir-Freundlich sorption isotherms. Thermodynamic parameters of the adsorption process such as DeltaG degrees, DeltaH degrees, and DeltaS degrees were calculated. The negative values of free energy reflected the spontaneous nature of adsorption. The typical dependence of dye uptake on temperature and the kinetics of adsorption indicated the process to be chemisorption. The grafting modifications greatly enhanced the adsorption performance of the biosorbents, especially in the case of powdered cross-linked chitosan grafted with acrylic acid, which exhibited a maximum adsorption capacity equal to 1.068 mmol/g. Kinetic studies also revealed a significant improvement of sorption rates by the modifications. Diffusion coefficients of the dye molecule were determined to be of the order 10(-13) - 10(-12) m2/s. Furthermore, desorption experiments affirmed the regenerative capability of the loaded material. PMID:17530870

Lazaridis, Nikolaos K; Kyzas, George Z; Vassiliou, Alexandros A; Bikiaris, Dimitrios N

2007-07-01

429

Endothelial Cells Derived From Nuclear Reprogramming  

PubMed Central

The endothelium plays a pivotal role in vascular homeostasis, regulating the tone of the vascular wall, and its interaction with circulating blood elements. Alterations in endothelial functions facilitate the infiltration of inflammatory cells and permit vascular smooth muscle proliferation and platelet aggregation. Therefore, endothelial dysfunction is an early event in disease processes including atherosclerosis, and because of its critical role in vascular health the endothelium is worthy of the intense focus it has received. However, there are limitations to studying human endothelial function in vivo, or human vascular segments ex vivo. Thus, methods for endothelial cell culture have been developed and refined. More recently, methods to derive endothelial cells from pluripotent cells have extended the scientific range of human endothelial cell studies. Pluripotent stem cells may be generated, expanded and then differentiated into endothelial cells for in vitro studies. Constructs for molecular imaging can also be employed to facilitate tracking these cells in vivo. Furthermore, one can generate patient-specific endothelial cells to study the effects of genetic or epigenetic alterations on endothelial behavior. Finally, there is the opportunity to apply these cells for vascular therapy. This review focuses on the generation of endothelial cells from stem cells; their characterization by genetic, histological and functional studies; and their translational applications.

Wong, Wing Tak; Huang, Ngan F.; Botham, Crystal M.; Sayed, Nazish; Cooke, John P.

2012-01-01

430

Surface Emissivity Derived From Multispectral Satellite Data  

NASA Technical Reports Server (NTRS)

Surface emissivity is critical for remote sensing of surface skin temperature and infrared cloud properties when the observed radiance is influenced by the surface radiation. It is also necessary to correctly compute the longwave flux from a surface at a given skin temperature. Surface emissivity is difficult to determine because skin temperature is an ill-defined parameter. The surface-emitted radiation may arise from a range of surface depths depending on many factors including soil moisture, vegetation, surface porosity, and heat capacity. Emissivity can be measured in the laboratory for pure surfaces. Transfer of laboratory measurements to actual Earth surfaces, however, is fraught with uncertainties because of their complex nature. This paper describes a new empirical approach for estimating surface skin temperature from a combination of brightness temperatures measured at different infrared wavelengths with satellite imagers. The method uses data from the new Geostationary Operational Environmental Satellite (GOES) imager to determine multispectral emissivities from the skin temperatures derived over the ARM Southern Great Plains domain.

Minnis, P.; Smith, W. L., Jr.; Young, D. F.

1998-01-01

431

Toxicity of a serotonin-derived neuromelanin.  

PubMed

Postoperative Cognitive Dysfunction (POCD) is associated with increased mortality in the elderly and may occur from lipid peroxidation in aging. We previously showed that sevoflurane sequesters acrolein, which promotes the formation of a novel species of a putative neuromelanin. The current study examined the properties of this serotonin-derived melanoid (SDM). The interaction of SDM with unilamellar vesicles (ULVs) was examined using lipid membrane probes. Vesicle disruption was investigated by leakage of dye from calcein-loaded ULVs. We observed that SDM decreased diphenyl-hexatriene fluorescence anisotropy and increased the temperature-dependent change in anisotropy. SDM changed the absorbance of merocyanin-bound ULVs. SDM increased detergent-mediated calcein leakage. SDM structure was dramatically altered upon interaction with ULVs. We also observed that SDM enhanced detergent-mediated leakage of loaded ULVs, suggesting that SDM may be neurotoxic. We propose that inhalational agents, which sequester acrolein, may promote the production of certain species of neuromelanin that depletes local serotonin and enhances neuronal vulnerability. PMID:20026057

Miller, Elizabeth D; Fibuch, Eugene E; Seidler, Norbert W

2010-01-01

432

Ultralow thermal conductivity of fullerene derivatives  

NASA Astrophysics Data System (ADS)

Recently, Duda [J. C. Duda, P. E. Hopkins, Y. Shen, and M. C. Gupta, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.110.015902 110, 015902 (2013)] reported that the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) has the lowest thermal conductivity ? ever observed in a fully dense solid, ? ? 0.03 W m-1 K-1. We have investigated a variety of phases and microstructures of PCBM and the closely related compound [6,6]-phenyl-C61-butyric acid n-butyl ester (PCBNB) and find that the thermal conductivities of PCBM and PCBNB films are mostly limited to the range 0.05 < ? < 0.06 W m-1 K-1 with a few samples having slightly higher ?. The conductivities we observe are ?70% larger than reported by Duda but are still “ultralow” in the sense that the thermal conductivity is a factor of ?3 below the conductivity predicted by the minimum thermal conductivity model using an estimate of the thermally excited modes per molecule.

Wang, Xiaojia; Liman, Christopher D.; Treat, Neil D.; Chabinyc, Michael L.; Cahill, David G.

2013-08-01

433

Synthesis and bioactivity of novel coumarin derivatives.  

PubMed

A series of coumarin derivatives (6-8) containing (E)-methyl 2-(methoxyimino)-2-phenylacetate, (E)-2-(methoxyimino)-N-methyl-2-phenylacetamide and methyl methoxy(phenyl)carbamate were synthesized from substituted resorcinols (1) and substituted beta-keto esters (2) as starting material via cyclization and condensation reactions. The test results indicated that (E)-methyl 2-{2-[(3-hexyl-4-methyl-coumarin-7-yloxy)methyl]phenyl}-2-(methoxyimino)acetate (6f) was the optimal structure with good fungicidal activity against cucumber grey mold (CGM) giving 100% control at 100 mg L(-1) concentration, much higher than that of coumoxystrobin. Methyl 2-[(3,4-dimethyl-coumarin -7-yloxy)methyl]phenyl(methoxy)carbamate (8a) was another optimal structure with good fungicidal activity against wheat powdery mildew (WPM) showing 100% control at 50 mg L(-1) concentration, at the same level as that of the commercial kresoxim-methyl, and very significantly higher than that of coumoxystrobin (no control against WPM at 400 mg L(-1)). PMID:22312739

Guan, Ai-Ying; Liu, Chang-Ling; Li, Miao; Li, Zhi-Nian; Zhang, Ming-Xing; Zhang, Hong

2011-12-01

434

Curdlan ester derivatives: synthesis, structure, and properties.  

PubMed

A series of ester derivatives of curdlan, which is a ?-(1 ? 3)-D-glucan extracellularly produced by microorganism, with varying alkyl chain lengths (C2-C12) were synthesized by the heterogeneous reaction using trifluoroacetic anhydride. As a result, high-molecular-weight (Mw ? 6 × 10(5)) and fully-acylated curdlan was obtained with relatively high yield (>70%). Thermal stability of curdlan was greatly improved by esterification. Crystallization was observed for curdlan esters with C2-C6 side chains. Both Tg (170 ? 50 °C) and Tm (290 ? 170 °C) of curdlan esters decreased with increasing the side-chain length. By the increase in the side-chain carbon number, curdlan esters showed lower Young's modulus and tensile strength, and larger elongation at break. Thus, material properties of curdlan esters can be controlled by changing the side-chain length. It was found that the increase of the side-chain length resulted in the decrease of crystallinity and the change of crystal structures. PMID:24528750

Marubayashi, Hironori; Yukinaka, Kazuyori; Enomoto-Rogers, Yukiko; Takemura, Akio; Iwata, Tadahisa

2014-03-15

435

Myeloid-Derived Suppressor Cells in Sepsis  

PubMed Central

Sepsis is a systemic, deleterious host response to widespread infection. Patients with sepsis will have documented or suspected infection which can progress to a state of septic shock or acute organ dysfunction. Since sepsis is responsible for nearly 3 million cases per year in China and severe sepsis is a common, expensive fatal condition in America, developing new therapies becomes a significant and worthwhile challenge. Clinical research has shown that sepsis-associated immunosuppression plays a central role in patient mortality, and targeted immune-enhancing therapy may be an effective treatment approach in these patients. As part of the inflammatory response during sepsis, there are elevations in the number of myeloid-derived suppressor cells (MDSCs). MDSCs are a heterogeneous population of immature myeloid cells that possess immunosuppressive activities via suppressing T-cell proliferation and activation. The role of MDSCs in sepsis remains uncertain. Some believe activated MDSCs are beneficial to the sepsis host by increasing innate immune responses and antimicrobial activities, while others think expansion of MDSCs leads to adaptive immune suppression and secondary infection. Herein, we discuss the complex role of MDSCs in immune regulation during sepsis, as well as the potential to target these cells for therapeutic benefit.

Qin, Chaojin; Shu, Qiang

2014-01-01

436

Dipyrazolopyridine derivatives as bright blue electroluminescent materials  

NASA Astrophysics Data System (ADS)

Very bright blue organic light emitting diodes were fabricated using highly fluorescent dipyrazolopyridine derivatives, 4-(4-substituted phenyl)-1,7-diphenyl-3,5-dimethyl-1,7dihydrodipyrazolo[3,4-b,4',3'-e]pyridine (PAP-X, X=CN, Ph, and OMe), as emitter by doping the dye in an electron-transporting host, 2,2',2''-(1,3,5-benzenetriyl)tris-[1-phenyl-1H-benzimidazole] (TPBI). Two hole-transporting layers, 4,4'-bis[N-(1-naphthyl-1-)-N-phenyl-amino]-biphenyl (NPB) and 4,4'-dicarbazolyl-1,1'-biphenyl (CBP) were used to achieve the emission from PAP-X. The devices with a general configuration of indium tin oxide/NPB/CBP/TPBI:PAP(2%)/Mg:Ag showed a bright blue emission. The PAP-CN-based device is exceptionally good, with a brightness of 11 200 cd/m2 at 14.2 V and the peak external quantum efficiency of 3.2%. The efficiency is the highest for the blue emission.

Tao, Y. T.; Balasubramaniam, E.; Danel, A.; Tomasik, P.

2000-08-01

437

Jet flames of a refuse derived fuel  

SciTech Connect

This paper is concerned with combustion of a refuse derived fuel in a small-scale flame. The objective is to provide a direct comparison of the RDF flame properties with properties of pulverized coal flames fired under similar boundary conditions. Measurements of temperature, gas composition (O{sub 2}, CO{sub 2}, CO, NO) and burnout have demonstrated fundamental differences between the coal flames and the RDF flames. The pulverized coals ignite in the close vicinity of the burner and most of the combustion is completed within the first 300 ms. Despite the high volatile content of the RDF, its combustion extends far into the furnace and after 1.8 s residence time only a 94% burnout has been achieved. This effect has been attributed not only to the larger particle size of fluffy RDF particles but also to differences in RDF volatiles if compared to coal volatiles. Substantial amounts of oily tars have been observed in the RDF flames even though the flame temperatures exceeded 1300 C. The presence of these tars has enhanced the slagging propensity of RDF flames and rapidly growing deposits of high carbon content have been observed. (author)

Weber, Roman; Kupka, Tomasz; Zajac, Krzysztof [Institute of Energy Process Engineering and Fuel Technology, Clausthal University of Technology, Agicolastrasse 4, 38 678 Clausthal-Zellerfeld (Germany)

2009-04-15

438

Bioactive quinic acid derivatives from Ageratina adenophora.  

PubMed

A novel quinic acid derivative, 5-O-trans-o-coumaroylquinic acid methyl ester (1), together with three known ones, chlorogenic acid methyl ester (2), macranthoin F (3) and macranthoin G (4), were isolated from the aerial parts of the invasive plant Ageratina adenophora (Spreng.). The structure of new compound 1 was elucidated on the basis of extensive spectroscopic analysis, including 1D- and 2D-NMR techniques. Compounds 2-4 were isolated from plant A. adenophora for the first time. All the compounds showed in vitro antibacterial activity toward five assayed bacterial strains, especially 3 and 4, which showed in vitro antibacterial activity against Salmonella enterica with MIC values of 7.4 and 14.7 ?M, respectively. Compound 1 was further found to display in vitro anti-fungal activity against spore germination of Magnaporthe grisea with an IC?? value 542.3 µM. These four compounds were also tested for their antioxidant activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) radical. PMID:24241153

Zhang, Mei; Liu, Wan-Xue; Zheng, Meng-Fei; Xu, Qiao-Lin; Wan, Fang-Hao; Wang, Jing; Lei, Ting; Zhou, Zhong-Yu; Tan, Jian-Wen

2013-01-01

439

Formation of cadaverine derivatives in Saccharomyces cerevisiae.  

PubMed

The higher homologues of cadaverine, aminopropylcadaverine (APC) and N,N-bis(3-aminopropyl)cadaverine (3APC) were formed by a wild-type strain of Saccharomyces cerevisiae, and by two mutant strains, spe 3-1 and spe 4-1, exhibiting point mutations in the genes for spermidine synthase and spermine synthase, respectively. This, together with the incomplete inhibition of APC and 3APC formation in the presence of inhibitors of S-adenosylmethionine decarboxylase and spermidine synthase, suggests that the cadaverine derivatives are formed partly by the operation of a different route. However, the yeast strains were unable to utilise [14C]aspartate and lysine to form APC and 3APC. Since the ornithine decarboxylase inhibitor alpha-difluoromethylornithine (DFMO) greatly reduced the formation of APC and 3APC, it is suggested that these compounds are formed preferentially in these yeast strains from cadaverine formed by ODC. APC and 3APC formation in the yeast strains was increased substantially following exposure to 37 degrees C for 2 h. PMID:8961564

Walters, D R; Cowley, T

1996-12-01

440

Derived relations and generalized alteration of preferences.  

PubMed

The present study examined the role of derived relations in the generalizability of the evaluative conditioning effect. Healthy university students participated. Four geometrical shapes were first established as discriminative stimuli for the contingent presentation of pictograms (B1, B2, C1, and C2, respectively). We then assessed the reinforcing properties of B1 versus B2, and C1 versus C2 by using simultaneous discrimination tasks: at baseline (baseline assessment), after pairing B1 with aversive slides plus noise and B2 with pleasant slides (test I), and after employing equivalence training and testing to establish B1 as equivalent to C1 and B2 as equivalent to C2 (test II). Most participants (82%) in the experimental condition, as compared with the control conditions (17% and 10%), selected the discriminative shapes for B2 (test I) and C2 (test II) on most trials, replicating and extending previous findings. Subsequently, the geometrical shapes were established as equivalent to the letters X, Y, W, and Z, respectively, which then served as antecedent stimuli in simultaneous discrimination tasks as before (test III). As was expected, only participants in the experimental condition showed preference for the novel letters that were established as equivalent to B2-producing and C2-producing shapes. These findings suggest that the evaluative conditioning effect may extend far beyond the stimulus being de/valuated and narrow the behavioral repertoire. PMID:23242738

Valdivia-Salas, Sonsoles; Dougher, Michael J; Luciano, Carmen

2013-06-01

441

Polyimides Derived from Novel Asymmetric Dianhydrides  

NASA Technical Reports Server (NTRS)

This invention relates to the compositions and processes for preparing thermoset and thermoplastic polyimides derived from novel asymmetrical dianhydrides: specifically 2,3,3',4' benzophenone dianhydride (a-BTDA), and 3,4'-(hexafluoroisopropylidene)diphthalic anhydride (a-6FDA). The a-BTDA anhydride is prepared by Suzuki coupling with catalysts from a mixed anhydride of 3,4-dimethylbenzoic acid or 2,3-dimethylbenzoic acid with 2,3-dimethylphenylboronic acid or 3,4-dimethylphenylboronic acid respectively, to form 2,3,3',4'-tetramethylbenzophenone which is oxidized to form 2,3,3',4'-benzophenonetetracarboxylic acid followed by cyclodehydration to obtain a-BTDA. The a-6FDA is prepared by nucleophilic triflouoromethylation of 2,3,3',4'-tetramethylbenzophenone with trifluoromethyltrimethylsilane to form 3,4'-(trifluoromethylmethanol)-bis(o-xylene) which is converted to 3,4'-(hexafluoroisopropylidene-bis(o-xylene). The 3,4'-(hexafluoroisopropylidene)-bis(o-xylene) is oxidized to the corresponding tetraacid followed by cyclodehydration to yield a-6FDA.

Chuang, Chun-Hua (Inventor)

2012-01-01

442

Myeloid Derived Suppressor Cells in Breast Cancer  

PubMed Central

Myeloid Derived Suppressor Cells (MDSCs) are a population of immature myeloid cells defined by their suppressive actions on immune cells such as T cells, dendritic cells, and natural killer cells. MDSCs typically are positive for the markers CD33 and CD11b but express low levels of HLADR in humans. In mice, MDSCs are typically positive for both CD11b and Gr1. These cells exert their suppressive activity on the immune system via the production of reactive oxygen species, arginase, and cytokines. These factors subsequently inhibit the activity of multiple protein targets such as the T cell receptor, STAT1, and indoleamine-pyrrole 2,3-dioxygenase. The numbers of MDSCs tend to increase with cancer burden while inhibiting MDSCs improves disease outcome in murine models. MDSCs also inhibit immune cancer therapeutics. In light of the poor prognosis of metastatic breast cancer in women and the correlation of increasing levels of MDSCs with increasing disease burden, the purposes of this review are to 1) discuss why MDSCs may be important in breast cancer, 2) describe model systems used to study MDSCs in vitro and in vivo, 3) discuss mechanisms involved in MDSC induction/function in breast cancer, and 4) present pre-clinical and clinical studies that explore modulation of the MDSC-immune system interaction in breast cancer. MDSCs inhibit the host immune response in breast cancer patients and diminishing MDSC actions may improve therapeutic outcomes.

Markowitz, Joseph; Wesolowski, Robert; Papenfuss, Tracey; Brooks, Taylor R.

2013-01-01

443

Deriving Chesapeake Bay Water Quality Standards  

USGS Publications Warehouse

Achieving and maintaining the water quality conditions necessary to protect the aquatic living resources of the Chesapeake Bay and its tidal tributaries has required a foundation of quantifiable water quality criteria. Quantitative criteria serve as a critical basis for assessing the attainment of designated uses and measuring progress toward meeting water quality goals of the Chesapeake Bay Program partnership. In 1987, the Chesapeake Bay Program partnership committed to defining the water quality conditions necessary to protect aquatic living resources. Under section 303(c) of the Clean Water Act, States and authorized tribes have the primary responsibility for adopting water quality standards into law or regulation. The Chesapeake Bay Program partnership worked with U.S. Environmental Protection Agency to develop and publish a guidance framework of ambient water quality criteria with designated uses and assessment procedures for dissolved oxygen, water clarity, and chlorophyll a for Chesapeake Bay and its tidal tributaries in 2003. This article reviews the derivation of the water quality criteria, criteria assessment protocols, designated use boundaries, and their refinements published in six addendum documents since 2003 and successfully adopted into each jurisdiction's water quality standards used in developing the Chesapeake Bay Total Maximum Daily Load.

Tango, Peter J.; Batiuk, Richard A.

2013-01-01

444

capture by carbide-derived carbons  

NASA Astrophysics Data System (ADS)

A series of carbide-derived carbons (CDCs) with different surface oxygen contents were prepared from TiC powder by chlorination and followed by HNO3 oxidation. The CDCs were characterized systematically by a variety of means such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultimate analysis, energy dispersive spectroscopy, N2 adsorption, and transmission electron microscopy. CO2 adsorption measurements showed that the oxidation process led to an increase in CO2 adsorption capacity of the porous carbons. Structural characterizations indicated that the adsorbability of the CDCs is not directly associated with its microporosity and specific surface area. As evidenced by elemental analysis, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy, the adsorbability of the CDCs has a linear correlation with their surface oxygen content. The adsorption mechanism was studied using quantum chemical calculation. It is found that the introduction of O atoms into the carbon surface facilitates the hydrogen bonding interactions between the carbon surface and CO2 molecules. This new finding demonstrated that not only the basic N-containing groups but also the acidic O-containing groups can enhance the CO2 adsorbability of porous carbon, thus providing a new approach to design porous materials with superior CO2 adsorption capacity.

Xing, Wei; Liu, Chao; Zhou, Ziyan; Zhou, Jin; Wang, Guiqiang; Zhuo, Shuping; Xue, Qingzhong; Song, Linhua; Yan, Zifeng

2014-04-01

445

Indole derivatives from a marine sponge-derived yeast as DPPH radical scavengers.  

PubMed

Two new indole derivatives (3, 4) and three known compounds (1, 2, 5) were isolated as radical scavengers from the culture filtrate of a marine sponge-derived yeast. Their structures were determined to be tyrosol (1), tryptophol (2), 2-(1H-indol-3-yl)ethyl 2-hydroxypropanoate (3), 2-(1H-indol-3-yl)ethyl 5-hydroxypentanoate (4), and cyclo(L-Pro-L-Tyr) (5) on the basis of their spectroscopic data. The absolute configurations of compounds 3 and 5 were determined by chiral HPLC analysis combined with synthesis and Marfey's method, respectively. Each obtained compound was evaluated for DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, and all compounds exhibited weak activities. PMID:19943625

Sugiyama, Yasumasa; Ito, Yuki; Suzuki, Motofumi; Hirota, Akira

2009-11-01

446

?-Pyrone derivatives, kojic acid methyl ethers from a marine-derived fungus altenaria sp  

Microsoft Academic Search

Kojic acid dimethyl ether (1), and the known kojic acid monomethyl ether (2), kojic acid (3) and phomaligol A (4) have been isolated from the organic extract of the broth of the marine-derived fungusAltenaria sp. collected from the surface of the marine green algaUlva pertusa. The structures were assigned on the basis of comprehensive spectroscopic analyses. Each isolate was tested

Xifeng Li; Jee Hean Jeong; Kang Tae Lee; Jung Rae Rho; Hong Dae Choi; Jung Sook Kang; Byeng Wha Son

2003-01-01

447

Tetrahydrobostrycin and 1-deoxytetrahydrobostrycin, two new hexahydroanthrone derivatives, from a marine-derived fungus Aspergillus sp.  

PubMed

Two new hexahydroanthrones, tetrahydrobostrycin (1) and 1-deoxytetrahydrobostrycin (2), were isolated from a marine-derived fungus Aspergillus sp. strain 05F16 collected at the coral reef of Manado, Indonesia, together with bostrycin and abscisic acid. The structures of new compounds were determined on the basis of their spectral data. Compound 1 showed weak antibacterial activity against Staphylococcus aureus and Escherichia coli and 2 against S. aureus. PMID:18776653

Xu, Jinzhong; Nakazawa, Takahiro; Ukai, Kazuyo; Kobayashi, Hisayoshi; Mangindaan, Remy E P; Wewengkang, Defny S; Rotinsulu, Henki; Namikoshi, Michio

2008-07-01

448

Enhancement of ventricular-subventricular zone-derived neurogenesis and oligodendrogenesis by erythropoietin and its derivatives  

PubMed Central

In the postnatal mammalian brain, stem cells in the ventricular-subventricular zone (V-SVZ) continuously generate neuronal and glial cells throughout life. Genetic labeling of cells of specific lineages have demonstrated that the V-SVZ is an important source of the neuroblasts and/or oligodendrocyte progenitor cells (OPCs) that migrate toward injured brain areas in response to several types of insult, including ischemia and demyelinating diseases. However, this spontaneous regeneration is insufficient for complete structural and functional restoration of the injured brain, so interventions to enhance these processes are sought for clinical applications. Erythropoietin (EPO), a clinically applied erythropoietic factor, is reported to have cytoprotective effects in various kinds of insult in the central nervous system. Moreover, recent studies suggest that EPO promotes the V-SVZ-derived neurogenesis and oligodendrogenesis. EPO increases the proliferation of progenitors in the V-SVZ and/or the migration and differentiation of their progenies in and around injured areas, depending on the dosage, timing, and duration of treatment, as well as the type of animal model used. On the other hand, EPO has undesirable side effects, including thrombotic complications. We recently demonstrated that a 2-week treatment with the EPO derivative asialo-EPO promotes the differentiation of V-SVZ-derived OPCs into myelin-forming mature oligodendrocytes in the injured white matter of neonatal mice without causing erythropoiesis. Here we present an overview of the multifaceted effects of EPO and its derivatives in the V-SVZ and discuss the possible applications of these molecules in regenerative medicine.

Kaneko, Naoko; Kako, Eisuke; Sawamoto, Kazunobu

2013-01-01

449

New macrolides and furan carboxylic acid derivative from the sponge-derived fungus Cladosporium herbarum.  

PubMed

Bioassay-guided fractionation of organic extracts of Cladosporium herbarum, isolated from the marine sponge Callyspongia aerizusa, yielded two new macrolide metabolites: pandangolide 3 and 4 (1 and 2) and the known fungal metabolites pandangolide 2 (3), cladospolide B (4), and iso-cladospolide B (5). Also isolated were the antimicrobially active (against Bacillus subtilis and Staphylococcus aureus) furan carboxylic acids: Sumiki's acid (6) and its new derivative, acetyl Sumiki's acid (7). All structures were elucidated by spectroscopic methods. PMID:11325242

Jadulco, R; Proksch, P; Wray, V; Sudarsono; Berg, A; Gräfe, U

2001-04-01

450

Megakaryocyte-derived microparticles: direct visualization and distinction from platelet-derived microparticles  

PubMed Central

Platelet microparticles are a normal constituent of circulating blood. Several studies have demonstrated positive correlations between thrombotic states and platelet microparticle levels. Yet little is known about the processes by which platelet microparticles are generated in vivo. We now characterize microparticles derived directly from megakaryocytes. Video microscopy of live mouse megakaryocytes demonstrated that microparticles form as submicron beads along the lengths of slender, unbranched micropodia. These microparticles are CD41+, CD42b+, and express surface phosphatidylserine. Megakaryocyte microparticle generation is resistant to inhibition of microtubule assembly, which is critical to platelet formation, and augmented by inhibition of actin polymerization. To determine whether circulating microparticles are derived primarily from activated platelets or megakaryocytes, we identified markers that distinguish between these 2 populations. CD62P and LAMP-1 were found only on mouse microparticles from activated platelets. In contrast, full-length filamin A was found in megakaryocyte-derived microparticles, but not microparticles from activated platelets. Circulating microparticles isolated from mice were CD62P?, LAMP-1? and expressed full-length filamin A, indicating a megakaryocytic origin. Similarly, circulating microparticles isolated from healthy volunteers were CD62P? and expressed full-length filamin A. Cultured human megakaryocytes elaborated microparticles that were CD41+, CD42b+, and express surface phosphatidylserine. These results indicate that direct production by megakaryocytes represents a physiologic means to generate circulating platelet microparticles.

Dilks, James R.; Richardson, Jennifer; Alden, Eva; Patel-Hett, Sunita R.; Battinelli, Elisabeth; Klement, Giannoula L.; Sola-Visner, Martha; Italiano, Joseph E.

2009-01-01

451

Derivation and characterization of human ESC-derived mesenchymal stem cells.  

PubMed

Mesenchymal stem cells (MSCs) are multipotent stem cells that have been isolated from numerous sources including human embryonic stem cells (hES). Derivation from hES is unique in that hES must be differentiated. In our hands, trypsinizing hES into single cells and plating them on gelatin coated plates in a DMEM medium supplemented with serum replacement media and FGF2 with either PDGF AB or EGF will induce differentiation of hES and selectively enhance the survival of MSCs over hES. Repeated passaging by trypsinization results in a highly enriched MSC culture. Enriched MSC cultures can be further purified to homogeneity by limiting dilution or FACS sorting for a CD105+ or CD73+ and CD24- cell population. The resulting hES-MSCs fulfill the ISCT minimal defining criteria for human MSCs, namely adherence to plastic, a surface antigen expression profile of CD29+, CD44+, CD49a+ CD49e+, CD73+, CD105+, CD166+, CD34-, CD45-, and a differentiation potential that includes adipogenesis, osteogenesis, and chondrogenesis. Finally, hES-MSCs can be extensively and stably propagated. This method of deriving hES-MSCs without the need for a xenogeneic feeder and use of animal serum could be used to derive clinically compliant MSCs from hESCs. PMID:21431516

Lai, Ruenn Chai; Choo, Andre; Lim, Sai Kiang

2011-01-01

452

Cognitive effects of cell-derived and synthetically-derived A? oligomers  

PubMed Central

Soluble forms of amyloid-? peptide (A?) are a molecular focus in Alzheimer's disease research. Soluble A? dimers (? 8 kDa), timers (? 12 kDa), tetramers (? 16 kDa) and A?*56 (? 56 kDa) have shown biological activity. These A? molecules have been derived from diverse sources, including chemical synthesis, transfected cells, and mouse and human brain, leading to uncertainty about toxicity and potency. Herein, synthetic A? peptide-derived oligomers, cell- and brain-derived low-n oligomers, and A?*56, were injected intracerebroventricularly (icv) into rats assayed under the Alternating Lever Cyclic Ratio (ALCR) cognitive assay. Cognitive deficits were detected at 1.3?M of synthetic A? oligomers and at low nanomolar concentrations of cell-secreted A? oligomers. Trimers, from transgenic mouse brain (Tg2576), did not cause cognitive impairment at any dose tested, whereas A?*56 induced concentration-dependent cognitive impairment at 0.9?M and 1.3?M. Thus, while multiple forms of A? have cognition impairing activity, there are significant differences in effective concentration and potency.

Reed, Miranda N.; Hofmeister, Jacki J.; Jungbauer, Lisa; Welzel, Alfred T.; Yu, Chunjiang; Sherman, Mathew A.; Lesne, Sylvain; LaDu, Mary Jo; Walsh, Dominic M.; Ashe, Karen H.; Cleary, James P.

2010-01-01

453

Synthesis and antitumor activity of some new xanthotoxin derivatives.  

PubMed

The condensation of 4-amino-9-methoxy psoralene (4-aminoxanthotoxin) with some aromatic aldehydes led to the formation of 4-arylimine xanthotoxin derivatives 2a-h, which were cyclized with mercaptoacetic acid to afford the thiazolidinone derivatives 3a-h. On the other hand, the reaction of aminoxanthotoxin 1 with some anhydrides afforded 4-imidione derivatives 3a-d. When 1 reacted with some isothiocyanates, the thiourea derivatives 5a-c were obtained but the thiourea derivative 6 was obtained when 1 reacted with ammonium thiocyanate. The thiourea derivative 6 was cyclized by the reaction with monochloroacetic acid in the presence of sodium acetate to give aminothiazolidinone derivative 7, but when the same reaction is carried out in the presence of pyridine, the thioxoimidazolidinone 8 was formed. The condensation of xanthotoxin sulphonamide with aromatic aldehydes gave the aryliminosulphonyl derivatives 9a-e. Xanthotoxin sulphonyl hydrazine condensed with some anhydride afforded sulphonic acid imide derivatives 10a-c. The antitumor and cytotoxic activities of 9 synthesized derivatives were tested, five compounds were found to be active, they inhibited the growth of HeLa cells. PMID:19217697

Abdel Hafez, Omaima M; Amin, Kamellia M; Abdel-Latif, Nehad A; Mohamed, Tahia K; Ahmed, Eman Y; Maher, Timothy

2009-07-01

454

Transformational derivation of programs using the Focus system  

NASA Technical Reports Server (NTRS)

A program derivation support system called Focus is being constructed. It will formally derive programs using the paradigm of program transformation. The following issues are discussed: (1) the integration of validation and program derivation activities in the Focus system; (2) its tree-based user interface; (3) the control of search spaces in program derivation; and (4) the structure and organization of program derivation records. The inference procedures of the system are based on the integration of functional and logic programming principles. This brings about a synthesis of paradigms that were heretofore considered far apart, such as logical and executable specifications and constructive and transformational approaches to program derivation. A great emphasis has been placed, in the design of Focus, on achieving small search spaces during program derivation. The program manipulation operations such as expansion, simplification and rewriting were designed with this objective. The role of operations that are expensive in search spaces, such as folding, has been reduced. Program derivations are documented in Focus in a way that the high level descriptions of derivations are expressed only using program level information. All the meta-level information, together with dependencies between derivations of program components, is automatically recorded by the system at a lower level of description for its own use in replay.

Reddy, Uday S.

1988-01-01

455

SAMZ: Satellite-Derived Management Zones  

NASA Technical Reports Server (NTRS)

The term "satellite-derived management zones" (SAMZ) denotes agricultural management zones that are subdivisions of large fields and that are derived from images of the fields acquired by instruments aboard Earth orbiting satellites during approximately the past 15 years. "SAMZ" also denotes the methodology and the software that implements the methodology for creating such zones. The SAMZ approach is one of several products of continuing efforts to realize a concept of precision agriculture, which involves optimal variations in seeding, in application of chemicals, and in irrigation, plus decisions to farm or not to farm certain portions of fields, all in an effort to maximize profitability in view of spatial and temporal variations in the growth and health of crops and in the chemical and physical conditions of soils. As used here, "management zone" signifies, more precisely, a subdivision of a field within which the crop production behavior is regarded as homogeneous. From the perspective of precision agriculture, management zones are the smallest subdivisions between which the seeding, application of chemicals, and other management parameters are to be varied. In the SAMZ approach, the main sources of data are the archives of satellite imagery that have been collected over the years for diverse purposes. One of the main advantages afforded by the SAMZ approach is that the data in these archives can be reused for purposes of precision agriculture at low cost. De facto, these archives contain information on all sources of variability within a field, including weather, crop types, crop management, soil types, and water drainage patterns. The SAMZ methodology involves the establishment of a Web-based interface based on an algorithm that generates management zones automatically and quickly from archival satellite image data in response to requests from farmers. A farmer can make a request by either uploading data describing a field boundary to the Web site or else drawing the boundary on a reference image. Hence, a farmer can start to engage in precision farming shortly after gaining access to the Web site, without need for incurring the high costs of conventional precision-agriculture data-collection practices that include collecting soil samples, mapping electrical conductivity of soil, and compiling multi-year crop-yield data. Given the boundary of a field, a SAMZ server computes the zones within the field in a three-stage process. In the first stage, a vector-valued image of the field is constructed by assembling, from the archives, the equivalent of a stack of the available images of the field (see figure). In the second stage, the vector-valued image is analyzed by use of a wavelet transform that detects spatial variations considered significant for precision farming while suppressing small-scale heterogeneities that are regarded as insignificant. In the third stage, a segmentation algorithm assembles the zones from smaller regions that have been identified in the wavelet analysis.

2004-01-01

456

Intracellular pigment epithelium-derived factor contributes to triglyceride degradation.  

PubMed

Pigment epithelium-derived factor is well known as a secreted glycoprotein with multiple functions, such as anti-angiogenic, neuroprotective and anti-tumor activities. However, its intracellular role remains unknown. The present study was performed to demonstrate the intracellular function of pigment epithelium-derived factor on triglyceride degradation. Hepatic pigment epithelium-derived factor levels increased at the early stage and subsequently decreased after 16 weeks in high-fat-diet-fed mice compared to those in chow-fed mice. Similarly, oleic acid led to long-term downregulation of pigment epithelium-derived factor in HepG2 cells. Endogenous pigment epithelium-derived factor was an intracellular protein with cytoplasmic distribution in hepatocytes by immunostaining. Exogenous FITC-labeled pigment epithelium-derived factor could be absorbed into hepatocytes. Both signal peptide deletion and full-length pigment epithelium-derived factor transfection HeLa cells and hepatocytes promoted triglyceride degradation. Intracellular pigment epithelium-derived factor co-immunoprecipitated with adipose triglyceride lipase and promoted triglyceride degradation in an adipose triglyceride lipase-dependent manner. Additionally, pigment epithelium-derived factor bound to the C-terminal of adipose triglyceride lipase (aa268-504) and adipose triglyceride lipase-G0/G1 switch gene-2 complex simultaneously, which facilitated adipose triglyceride lipase-G0/G1 switch gene-2 translocation onto lipid droplet using bimolecular fluorescence complementation assay. Moreover, knockdown of endogenous pigment epithelium-derived factor in hepatocytes diminished triglyceride degradation. Taken together, these results indicate that hepatic pigment epithelium-derived factor was decreased in obese mice accompanied with hepatic steatosis. Intracellular pigment epithelium-derived factor binds to and facilitates adipose triglyceride lipase translocation onto lipid droplet, which promotes triglyceride degradation. These findings suggest that a decreased level of hepatic pigment epithelium-derived factor may contribute to hepatic steatosis in obesity. PMID:23886488

Dai, Zhiyu; Zhou, Ti; Li, Cen; Qi, Weiwei; Mao, Yuling; Lu, Juling; Yao, Yachao; Li, Lei; Zhang, Ting; Hong, Honghai; Li, Shuai; Cai, Weibin; Yang, Zhonghan; Ma, Jianxing; Yang, Xia; Gao, Guoquan

2013-09-01

457

Gravity derived Moho for South America  

NASA Astrophysics Data System (ADS)

Crustal structure in South America is one of the least understood among the Earth's continental areas. Variations in crustal thickness are still poorly constrained over large portions of the continent because of scarce or unevenly distributed crustal thickness estimates throughout South America. To address this scarce and inhomogeneous data cover we explore the possibility to derive crustal thickness from satellite gravity data. In this study, we utilize the combined gravity model EIGEN-6C, which is composed of GOCE and other gravity data. The Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite has a much more uniform spatial resolution than any land-based gravity or seismic survey in South America. The gravity data inversion is for a simple two-layer model with fixed density contrast over the interface, the Moho. The method is not relying on point constraint data and assumes that all of the signal is related to topography of the Moho. Model quality can therefore be assessed by a comparison with point observations on crustal thickness. We show that for the stable part of the continent 90% of our estimates are similar, within error bounds, to seismic observations. Variations occur in active orogenic zones or regions with suspected non-standard Moho density contrasts. A comparison with seismological models shows a high correlation with the most recent model. Especially in areas where continental and global models of crustal structure have limitations in terms of wave paths or point constraints the gravity based model provides a unique continuity of crustal structure providing new insights on structure and tectonics and increase our understanding of the Earth's structure underneath South America.

van der Meijde, M.; Julià, J.; Assumpção, M.

2013-12-01

458

Derivation of the high field semiconductor equations  

SciTech Connect

Electron and hole densities evolve in x-z phase space according to Boltzmann equations. When the mean free path of the particles is short and electric force on the particles is weak, a well-known expansion can be used to solve the Boltzmann equation. This asymptotic solution shows that the spatial density of electrons and holes evolves according to diffusion-drift equations. As devices become smaller, electric fields become stronger, which renders the Basic Semiconductor Equations increasingly inaccurate. To remedy this problem, we use singular perturbation techniques to obtain a new asymptotic expansion for the Boltzmann equation. Like the Hilbert expansion, the new expansion requires the mean free path to be short compared to all macroscopic length scales. However, it does not require the electric forces to be weak. The new expansion shows that spatial densities obey diffusion-drift equations as before, but the diffusivity D and mobility {mu} turn out to be nonlinear functions of the electric field. In particular, our analysis determines the field-dependent mobilities {mu}(E) and diffusivities D(E) directly from the scattering operator. By carrying out this asymptotic expansion to higher order, we obtain the high frequency corrections to the drift velocity and diffusivity, and also the corrections due to gradients in the electric field. Remarkably, we find that Einsteins's relation is still satisfied, even with these corrections. The new diffusion-drift equations, together with Poissons' equation for the electric field, form the high-field semiconductor equations, which can be expected to be accurate regardless of the strength of the electric fields within the semiconductor. In addition, our analysis determines the entire momentum distribution of the particles, so we derive a very accurate first moment model for semi-conductors by substituting the asymptotically-correct distribution back into the Boltzmann equation and taking moments.

Hagan, P.S. (Los Alamos National Lab., NM (United States)); Cox, R.W. (Department of Computer Information Science, Indiana University, Purdue University, Indianapolis (USA)); Wagner, B.A. (Arizona Univ., Tucson, AZ (United States). Dept. of Mathematics)

1991-01-01

459

Functionalized bacterial cellulose derivatives and nanocomposites.  

PubMed

Bacterial cellulose (BC) is a fascinating and renewable natural nanomaterial characterized by favorable properties such as remarkable mechanical properties, porosity, water absorbency, moldability, biodegradability and excellent biological affinity. Intensive research and exploration in the past few decades on BC nanomaterials mainly focused on their biosynthetic process to achieve the low-cost preparation and application in medical, food, advanced acoustic diaphragms, and other fields. These investigations have led to the emergence of more diverse potential applications exploiting the functionality of BC nanomaterials. This review gives a summary of construction strategies including biosynthetic modification, chemical modification, and different in situ and ex situ patterns of functionalization for the preparation of advanced BC-based functional nanomaterials. The major studies being directed toward elaborate designs of highly functionalized material systems for many-faceted prospective applications. Simple biosynthetic or chemical modification on BC surface can improve its compatibility with different matrix and expand its utilization in nano-related applications. Moreover, based on the construction strategies of functional nanomaterial system, different guest substrates including small molecules, inorganic nanoparticles or nanowires, and polymers can be incorporated onto the surfaces of BC nanofibers to prepare various functional nanocomposites with outstanding properties, or significantly improved physicochemical, catalytic, optoelectronic, as well as magnetic properties. We focus on the preparation methods, formation mechanisms, and unique performances of the different BC derivatives or BC-based nanocomposites. The special applications of the advanced BC-based functional nanomaterials, such as sensors, photocatalytic nanomaterials, optoelectronic devices, and magnetically responsive membranes are also critically and comprehensively reviewed. PMID:24299873

Hu, Weili; Chen, Shiyan; Yang, Jingxuan; Li, Zhe; Wang, Huaping

2014-01-30

460

Deriving Information from Sampling and Diving  

NASA Astrophysics Data System (ADS)

We investigate the impact of sampling and diving in the solution of constraint satisfaction problems. A sample is a complete assignment of variables to values taken from their domain according to a a given distribution. Diving consists in repeatedly performing depth first search attempts with random variable and value selection, constraint propagation enabled and backtracking disabled; each attempt is called a dive and, unless a feasible solution is found, it is a partial assignment of variables (whereas a sample is a -possibly infeasible- complete assignment). While the probability of finding a feasible solution via sampling or diving is negligible if the problem is difficult enough, samples and dives are very fast to generate and, intuitively, even when they are infeasible, they give some statistic information on search space structure. The aim of this paper is to understand to what extent it is possible to help the CSP solving process with information derived from sampling and diving. In particular, we are interested in extracting from samples and dives precise indications on how good/bad are individual variable-value assignments with respect to feasibility. We formally prove that even uniform sampling could provide precise evaluation of the quality of variable-value assignments; as expected, this requires huge sample sizes and is therefore not useful in practice. On the contrary, diving seems to be much better suited for assignment evaluation purposes. Three dive features are identified and evaluated on a collection of Partial Latin Square instances, showing that diving provides information that can be fruitfully exploited. Many promising direction for future research are proposed.

Lombardi, Michele; Milano, Michela; Roli, Andrea; Zanarini, Alessandro

461

Interaction of gramicidin derivatives with phospholipid monolayers.  

PubMed

A study of the interaction of gramicidin A (gA), tert-butyloxycarbonyl-gramicidin (g-BOC), and desformyl gramicidin (g-des) with dioleoyl phosphatidylcholine (DOPC) and DOPC/phosphatidylserine (PS) mixed monolayers on a mercury electrode is reported in this paper. Experiments were carried out in electrolytes KCl (0.1 mol dm(-3)) and Mg(NO3)2 (0.05 mol dm(-3)). The channel-forming properties of the gramicidins were studied by following the reduction of Tl(I) to Tl(Hg). The frequency dependence of the complex impedance of coated electrode surfaces in the presence and absence of the gramicidins was estimated between 65,000 and 0.1 Hz at potentials of -0.4 V versus Ag/AgCl with 3.5 mol dm(-3) KCl. Epifluorescence microscopy was used to qualitatively correlate the interaction of the gramicidin peptides with dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG) at the air-water interface. gA was shown to form Tl+ conducting channels in a DOPC monolayer, while g-BOC and g-des did not. In DOPC-30% PS (DOPC-0.3PS) layers, there is a marked increase in channel activity of all three gramicidin derivatives. None of the peptides facilitate the permeability of the DOPC-0.3PS layer to Cd2+. All three peptides interact with the layer as shown by capacitance-potential curves and impedance spectroscopy indicated by penetration of the peptide into the dielectric, an increase in surface "roughness", and an increased significance of low-frequency relaxations. The order of interaction is gA > g-des > g-BOC. The epifluorescence study of DPPC and DPPG layers at the air-water interface shows a selective action of the different gramicidins. PMID:15461520

Whitehouse, C; Gidalevitz, D; Cahuzac, M; Koeppe Ii, Roger E; Nelson, A

2004-10-12

462

Tachometers Derived From a Brushless DC Motor  

NASA Technical Reports Server (NTRS)

The upper part of the figure illustrates the major functional blocks of a direction-sensitive analog tachometer circuit based on the use of an unexcited two-phase brushless dc motor as a rotation transducer. The primary advantages of this circuit over many older tachometer circuits include the following: Its output inherently varies linearly with the rate of rotation of the shaft. Unlike some tachometer circuits that rely on differentiation of voltages with respect to time, this circuit relies on integration, which results in signals that are less noisy. There is no need for an additional shaft-angle sensor, nor is there any need to supply electrical excitation to a shaft-angle sensor. There is no need for mechanical brushes (which tend to act as sources of electrical noise). The underlying concept and electrical design are relatively simple. This circuit processes the back-electromagnetic force (back-emf) outputs of the two motor phases into a voltage directly proportional to the instantaneous rate (sign magnitude) of rotation of the shaft. The processing in this circuit effects a straightforward combination of mathematical operations leading to a final operation based on the well-known trigonometric identity (sin x)2 + (cos x)2 = 1 for any value of x. The principle of operation of this circuit is closely related to that of the tachometer circuit described in Tachometer Derived From Brushless Shaft-Angle Resolver (MFS-28845), NASA Tech Briefs, Vol. 19, No. 3 (March 1995), page 39. However, the present circuit is simpler in some respects because there is no need for sinusoidal excitation of shaftangle- resolver windings.

Howard, David E.; Smith, Dennis A.

2007-01-01

463

Biological activities of water-soluble fullerene derivatives  

NASA Astrophysics Data System (ADS)

Three types of water-soluble fullerene derivatives were synthesized and their biological activities were investigated. C60-dimalonic acid, an anionic fullerene derivative, showed antioxidant activity such as quenching of superoxide and relief from growth inhibition of E. coli by paraquat. C60-bis(7V,7V-dimethylpyrrolidinium iodide), a cationic fullerene derivative, has antibacterial activity and antiproliferative effect on cancer cell lines. The mechanism is suggested to be respiratory chain inhibition by reactive oxygen species produced by the cationic fullerene derivative. Proline-type fullerene derivatives showed strong inhibition activities on HIV-reverse transcriptase. The IC50 values were remarkably lower than nevirapine, a clinically used anti-HIV drug. Fullerene derivatives have a big potential for a new type of lead compound to be used as medicine.

Nakamura, S.; Mashino, T.

2009-04-01

464

Contracted auxiliary Gaussian basis integral and derivative evaluation.  

PubMed

The rapid evaluation of two-center Coulomb and overlap integrals between contracted auxiliary solid harmonic Gaussian functions is examined. Integral expressions are derived from the application of Hobson's theorem and Dunlap's product and differentiation rules of the spherical tensor gradient operator. It is shown that inclusion of the primitive normalization constants greatly simplifies the calculation of contracted functions corresponding to a Gaussian multipole expansion of a diffuse charge density. Derivative expressions are presented and it is shown that chain rules are avoided by expressing the derivatives as a linear combination of auxiliary integrals involving no more than five terms. Calculation of integrals and derivatives requires the contraction of a single vector corresponding to the monopolar result and its scalar derivatives. Implementation of the method is discussed and comparison is made with a Cartesian Gaussian-based method. The current method is superior for the evaluation of both integrals and derivatives using either primitive or contracted functions. PMID:18282025

Giese, Timothy J; York, Darrin M

2008-02-14

465

Contracted auxiliary Gaussian basis integral and derivative evaluation  

NASA Astrophysics Data System (ADS)

The rapid evaluation of two-center Coulomb and overlap integrals between contracted auxiliary solid harmonic Gaussian functions is examined. Integral expressions are derived from the application of Hobson's theorem and Dunlap's product and differentiation rules of the spherical tensor gradient operator. It is shown that inclusion of the primitive normalization constants greatly simplifies the calculation of contracted functions corresponding to a Gaussian multipole expansion of a diffuse charge density. Derivative expressions are presented and it is shown that chain rules are avoided by expressing the derivatives as a linear combination of auxiliary integrals involving no more than five terms. Calculation of integrals and derivatives requires the contraction of a single vector corresponding to the monopolar result and its scalar derivatives. Implementation of the method is discussed and comparison is made with a Cartesian Gaussian-based method. The current method is superior for the evaluation of both integrals and derivatives using either primitive or contracted functions.

Giese, Timothy J.; York, Darrin M.

2008-02-01

466

Derivation of Formulations 1 and 1A of Farassat  

NASA Technical Reports Server (NTRS)

Formulations 1 and 1A are the solutions of the Ffowcs Williams-Hawkings (FW-H) equation with surface sources only when the surface moves at subsonic speed. Both formulations have been successfully used for helicopter rotor and propeller noise prediction for many years although we now recommend using Formulation 1A for this purpose. Formulation 1 has an observer time derivative that is taken numerically, and thus, increasing execution time on a computer and reducing the accuracy of the results. After some discussion of the Green's function of the wave equation, we derive Formulation 1 which is the basis of deriving Formulation 1A. We will then show how to take this observer time derivative analytically to get Formulation 1A. We give here the most detailed derivation of these formulations. Once you see the whole derivation, you will ask yourself why you did not do it yourself!

Farassat, F.

2007-01-01

467

Measuring displacement derivatives by electronic speckle pattern shearing interferometry (ESPSI)  

NASA Astrophysics Data System (ADS)

Electronic speckle pattern shearing interferometry (ESPSI), also known as shearography, is a whole-field optical technique used to measure approximately the fields of displacement derivatives. The accurate measurements of these derivatives have two problems: first, although ESPSI results are approximately equal to the derivatives, they are equal to the derivatives only if the shear distance tends to zero, hence, if experimental data rendered by ESPSI are taken directly as equal to the derivatives, the measurements may carry an important shearing error; second, ESPSI yields values relative to a reference value at a specific location of the field that can be very difficult to determine accurately. In this paper, we propose a general procedure to compensate the shearing error and to introduce the reference by adding two quantities to the values rendered by ESPSI. As an example, we measured a displacement derivative field induced on a metallic sheet specimen by applying tensile load.

Labbe, Fernando; Cordero, Raúl R.; Martínez, Amalia; Rodríguez-Vera, Ramón

2005-08-01

468

Comparison of human adipose-derived stem cells and bone marrow-derived stem cells in a myocardial infarction model.  

PubMed

Treatment of myocardial infarction (MI) with bone marrow-derived mesenchymal stem cells and recently also adipose-derived stem cells has shown promising results. In contrast to clinical trials and their use of autologous bone marrow-derived cells from the ischemic patient, the animal MI models are often using young donors and young, often immune-compromised, recipient animals. Our objective was to compare bone marrow-derived mesenchymal stem cells with adipose-derived stem cells from an elderly ischemic patient in the treatment of MI using a fully grown non-immune-compromised rat model. Mesenchymal stem cells were isolated from adipose tissue and bone marrow and compared with respect to surface markers and proliferative capability. To compare the regenerative potential of the two stem cell populations, male Sprague-Dawley rats were randomized to receive intramyocardial injections of adipose-derived stem cells, bone marrow-derived mesenchymal stem cells, or phosphate-buffered saline 1 week following induction of MI. After 4 weeks, left ventricular ejection fraction (LVEF) was improved in the adipose-derived stem cell group, and scar wall thickness was greater compared with the saline group. Adipose-derived as well as bone marrow-derived mesenchymal stem cells prevented left ventricular end diastolic dilation. Neither of the cell groups displayed increased angiogenesis in the myocardium compared with the saline group. Adipose-derived stem cells from a human ischemic patient preserved cardiac function following MI, whereas this could not be demonstrated for bone marrow-derived mesenchymal stem cells, with only adipose-derived stem cells leading to an improvement in LVEF. Neither of the stem cell types induced myocardial angiogenesis, raising the question whether donor age and health have an effect on the efficacy of stem cells used in the treatment of MI. PMID:23211469

Rasmussen, Jeppe Grøndahl; Frøbert, Ole; Holst-Hansen, Claus; Kastrup, Jens; Baandrup, Ulrik; Zachar, Vladimir; Fink, Trine; Simonsen, Ulf

2014-02-01

469

Derivation of pluripotent epiblast stem cells from mammalian embryos  

Microsoft Academic Search

Although the first mouse embryonic stem (ES) cell lines were derived 25 years ago using feeder-layer-based blastocyst cultures, subsequent efforts to extend the approach to other mammals, including both laboratory and domestic species, have been relatively unsuccessful. The most notable exceptions were the derivation of non-human primate ES cell lines followed shortly thereafter by their derivation of human ES cells.

I. Gabrielle M. Brons; Lucy E. Smithers; Matthew W. B. Trotter; Peter Rugg-Gunn; Bowen Sun; Sarah K. Howlett; Amanda Clarkson; Lars Ahrlund-Richter; Roger A. Pedersen; Ludovic Vallier

2007-01-01

470

Comparisons of bridges flutter derivatives and generalized ones  

Microsoft Academic Search

The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude\\u000a and wind velocity. The concept of “generalized flutter derivative” is proposed, and its physical meaning is illustrated. The\\u000a graphs of the generalized flutter derivatives of plate and Sutong Bridge section model are plotted. The characteristics of\\u000a all generalized flutter derivatives are

Fuyou Xu; Airong Chen; Zhe Zhang; Cailiang Huang

2009-01-01

471

Status report on the NCSL Intrinsic/Derived Standards Committee  

SciTech Connect

The history and present status of the NCSL intrinsic/Derived Standards Committee is presented, including a review of the current published Recommended Intrinsic/Derived Standard Practices (RISPs) and the four Working Groups that are in the process of developing new RISPs. One of the documents under development is a Reference Catalogue that documents important information associated with over forty intrinsic/derived standards. The generic information on each standard in the Catalogue, as well as its Table of contents, are presented.

Pettit, R.B.

1994-05-01

472

Derivation of human embryonic stem cells from single blastomeres  

Microsoft Academic Search

This protocol details a method to derive human embryonic stem (hES) cells from single blastomeres. Blastomeres are removed from morula (eight-cell)-stage embryos and cultured until they form multicell aggregates. These blastomere-derived cell aggregates are plated into microdrops seeded with mitotically inactivated feeder cells, and then connected with neighboring microdrops seeded with green fluorescent protein-positive hES cells. The resulting blastomere-derived outgrowths

Irina Klimanskaya; Young Chung; Sandy Becker; Shi-Jiang Lu; Robert Lanza

2007-01-01

473

Synthesis and antimultidrug resistance evaluation of icariin and its derivatives  

Microsoft Academic Search

A series of icariin derivatives were synthesized. Their multidrug resistance (MDR) reversal activities were evaluated by MTT assay and the results indicated that the derivatives were the potent modulators of MDR. It was showed that the derivatives significantly increased the intracellular accumulation of ADR in MCF-7\\/ADR cells compared with drug sensitive MCF-7 cells. The results of bi-directional assay and reverse

Dong-Fang Liu; Yan-Ping Li; Tian-Miao Ou; Shi-Liang Huang; Lian-Quan Gu; Min Huang; Zhi-Shu Huang

2009-01-01

474

New active poly(ethylene glycol) derivative for amino coupling  

Microsoft Academic Search

The synthesis and characterization of an active poly(ethylene glycol) (PEG) derivative with new properties has been afforded starting from a side reaction of N-hydroxysuccinimide (NHS) in presence of N,N-dicyclohexylcarbodiimide (DCC). In particular, a ring opening of NHS in presence of DCC forms a ?-alanine active derivative, through Lossen rearrangement, which then reacts with PEG–NH2 yielding the active PEG derivative: PEG–NH–CO–?Ala–NH–CO–NHS.

G. Pasut; F. Caboi; R. Schrepfer; G. Tonon; O. Schiavon; F. M. Veronese

2007-01-01

475

The thiazole derivative CPTH6 impairs autophagy  

PubMed Central

We have previously demonstrated that the thiazole derivative 3-methylcyclopentylidene-[4-(4?-chlorophenyl)thiazol-2-yl]hydrazone (CPTH6) induces apoptosis and cell cycle arrest in human leukemia cells. The aim of this study was to evaluate whether CPTH6 is able to affect autophagy. By using several human tumor cell lines with different origins we demonstrated that CPTH6 treatment induced, in a dose-dependent manner, a significant increase in autophagic features, as imaged by electron microscopy, immunoblotting analysis of membrane-bound form of microtubule-associated protein 1 light chain 3 (LC3B-II) levels and by appearance of typical LC3B-II-associated autophagosomal puncta. To gain insights into the molecular mechanisms of elevated markers of autophagy induced by CPTH6 treatment, we silenced the expression of several proteins acting at different steps of autophagy. We found that the effect of CPTH6 on autophagy developed through a noncanonical mechanism that did not require beclin-1-dependent nucleation, but involved Atg-7-mediated elongation of autophagosomal membranes. Strikingly, a combined treatment of CPTH6 with late-stage autophagy inhibitors, such as chloroquine and bafilomycin A1, demonstrates that under basal condition CPTH6 reduces autophagosome turnover through an impairment of their degradation pathway, rather than enhancing autophagosome formation, as confirmed by immunofluorescence experiments. According to these results, CPTH6-induced enhancement of autophagy substrate p62 and NBR1 protein levels confirms a blockage of autophagic cargo degradation. In addition, CPTH6 inhibited autophagosome maturation and compounds having high structural similarities with CPTH6 produced similar effects on the autophagic pathway. Finally, the evidence that CPTH6 treatment decreased ?-tubulin acetylation and failed to increase autophagic markers in cells in which acetyltransferase ATAT1 expression was silenced indicates a possible role of ?-tubulin acetylation in CPTH6-induced alteration in autophagy. Overall, CPTH6 could be a valuable agent for the treatment of cancer and should be further studied as a possible antineoplastic agent.

Ragazzoni, Y; Desideri, M; Gabellini, C; De Luca, T; Carradori, S; Secci, D; Nescatelli, R; Candiloro, A; Condello, M; Meschini, S; Del Bufalo, D; Trisciuoglio, D

2013-01-01

476

Rigorous derivation of electromagnetic self-force  

SciTech Connect

During the past century, there has been considerable discussion and analysis of the motion of a point charge in an external electromagnetic field in special relativity, taking into account 'self-force' effects due to the particle's own electromagnetic field. We analyze the issue of 'particle motion' in classical electromagnetism in a rigorous and systematic way by considering a one-parameter family of solutions to the coupled Maxwell and matter equations corresponding to having a body whose charge-current density J{sup a}({lambda}) and stress-energy tensor T{sub ab}({lambda}) scale to zero size in an asymptotically self-similar manner about a worldline {gamma} as {lambda}{yields}0. In this limit, the charge, q, and total mass, m, of the body go to zero, and q/m goes to a well-defined limit. The Maxwell field F{sub ab}({lambda}) is assumed to be the retarded solution associated with J{sup a}({lambda}) plus a homogeneous solution (the 'external field') that varies smoothly with {lambda}. We prove that the worldline {gamma} must be a solution to the Lorentz force equations of motion in the external field F{sub ab}({lambda}=0). We then obtain self-force, dipole forces, and spin force as first-order perturbative corrections to the center-of-mass motion of the body. We believe that this is the first rigorous derivation of the complete first-order correction to Lorentz force motion. We also address the issue of obtaining a self-consistent perturbative equation of motion associated with our perturbative result, and argue that the self-force equations of motion that have previously been written down in conjunction with the 'reduction of order' procedure should provide accurate equations of motion for a sufficiently small charged body with negligible dipole moments and spin. (There is no corresponding justification for the non-reduced-order equations.) We restrict consideration in this paper to classical electrodynamics in flat spacetime, but there should be no difficulty in extending our results to the motion of a charged body in an arbitrary globally hyperbolic curved spacetime.

Gralla, Samuel E.; Harte, Abraham I.; Wald, Robert M. [Enrico Fermi Institute and Department of Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637 (United States)

2009-07-15

477

Asteroid Thermal Properties Derived from Meteorite Data  

NASA Astrophysics Data System (ADS)

The thermal inertia of an asteroid’s surface determines its response to the various Yarkovsky effects, while its internal thermal diffusivity controls its thermal evolution. Each quantity is a function of the material’s thermal conductivity, heat capacity, and density. Over the past ten years we have conducted a detailed survey measuring density in meteorites and are currently in the early stages of similar surveys for thermal conductivity and heat capacity. While various meteorite types differ in small but significant ways, for asteroid studies typical average values of these quantities can be estimated to within about 10%. (Metallic asteroids would have significantly different behavior.) The most important variable controlling density and thermal conductivity is porosity, P, while heat capacity is a strong function of temperature, T. Most stony meteorite densities are within 10% of 3500*(1-P) (SI units); basaltic and volatile rich meteorites are 10% to 30% less dense. Thermal conductivity in the temperature range of interest in the asteroid belt is nearly constant with temperature but varies strongly with porosity; assuming the trend seen for meteorite porosities up to 25% can be extrapolated to higher porosities, with zero conductivity at 100% porosity, a typical conductivity (for porosities greater than 2%) can be approximated by k = 0.11/P - 0.11 (SI units). Heat capacity ranges from under 250 J/kgK at 100 K to over 600 J/kgK at 250 K; over these temperatures this variation can be fitted by a quadratic in T. From these formulae we can derive representative values for thermal inertia and diffusivity and see how they vary as a function of porosity and temperature values appropriate for most asteroids. The greatest variation is with porosity. Thermal diffusivity drops by nearly two orders of magnitude from 0 to 20% porosity, more slowly at higher porosities. Thermal inertia (at 200K) varies from 3000 (SI units) near zero porosity down to 3 as porosity approaches 100%; 10% porosity has a thermal inertia near 1000 while 90% porous is about 60. Literature asteroid thermal inertias range from as high as 1000 to below 30; asteroid thermal inertias below 100 demand an extremely porous (>80%) surface.

Consolmagno, Guy; Macke, R. J.; Britt, D. T.

2013-10-01

478

Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings  

SciTech Connect

The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and processing techniques for these coatings. In addition, we investigated the effect of microstructure on the mechanical properties and oxidation protection ability of the coatings. Coatings were developed to provide oxidation protection to both ferritic and austentic alloys and Ni-based alloys. The coatings that we developed are based on low viscosity pre-ceramic polymers. Thus they can be easily applied to any shape by using a variety of techniques including dip-coating, spray-coating and painting. The polymers are loaded with a variety of nanoparticles. The nanoparticles have two primary roles: control of the final composition and phases (and hence the properties); and control of the shrinkage during thermal decomposition of the polymer. Thus the selection of the nanoparticles was the most critical aspect of this project. Based on the results of the processing studies, the performance of selected coatings in oxidizing conditions (both static and cyclic) was investigated.

Rajendra Bordia

2009-07-31

479

Equivalence of Conventionally-Derived and Parthenote-Derived Human Embryonic Stem Cells  

PubMed Central

Background As human embryonic stem cell (hESC) lines can be derived via multiple means, it is important to determine particular characteristics of individual lines that may dictate the applications to which they are best suited. The objective of this work was to determine points of equivalence and differences between conventionally-derived hESC and parthenote-derived hESC lines (phESC) in the undifferentiated state and during neural differentiation. Methodology/Principal Findings hESC and phESC were exposed to the same expansion conditions and subsequent neural and retinal pigmented epithelium (RPE) differentiation protocols. Growth rates and gross morphology were recorded during expansion. RTPCR for developmentally relevant genes and global DNA methylation profiling were used to compare gene expression and epigenetic characteristics. Parthenote lines proliferated more slowly than conventional hESC lines and yielded lower quantities of less mature differentiated cells in a neural progenitor cell (NPC) differentiation protocol. However, the cell lines performed similarly in a RPE differentiation protocol. The DNA methylation analysis showed similar general profiles, but the two