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91.
H Kumari SR Kline CL Dennis AV Mossine RL Paul CA Deakyne JL Atwood 《Angewandte Chemie (International ed. in English)》2012,51(37):9263-9266
Metal-containing tubes: The structures of several iron-containing C-methylpyrogallol[4]arene (PgC(1) ) nanoassemblies were studied in both the solid and solution phases. The nanoassemblies have a tubular architecture with the iron as part of the framework (see picture; gray C, red O, turquoise/blue Fe), and magnetic analysis suggests a canted or spiral arrangement of the iron centers. 相似文献
92.
Cho E Risko C Kim D Gysel R Miller NC Breiby DW McGehee MD Toney MF Kline RJ Bredas JL 《Journal of the American Chemical Society》2012,134(14):6177-6190
We use a systematic approach that combines experimental X-ray diffraction (XRD) and computational modeling based on molecular mechanics and two-dimensional XRD simulations to develop a detailed model of the molecular-scale packing structure of poly(2,5-bis (3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT-C(14)) films. Both uniaxially and biaxially aligned films are used in this comparison and lead to an improved understanding of the molecular-scale orientation and crystal structure. We then examine how individual polymer components (i.e., conjugated backbone and alkyl side chains) contribute to the complete diffraction pattern, and how modest changes to a particular component orientation (e.g., backbone or side-chain tilt) influence the diffraction pattern. The effects on the polymer crystal structure of varying the alkyl side-chain length from C(12) to C(14) and C(16) are also studied. The accurate determination of the three-dimensional polymer structure allows us to examine the PBTTT electronic band structure and intermolecular electronic couplings (transfer integrals) as a function of alkyl side-chain length. This combination of theoretical and experimental techniques proves to be an important tool to help establish the relationship between the structural and electronic properties of polymer thin films. 相似文献
93.
Margaret C. Kline David L. Duewer John C. Travis Melody V. Smith Janette W. Redman Peter M. Vallone Amy E. Decker John M. Butler 《Analytical and bioanalytical chemistry》2009,394(4):1183-1192
Modern highly multiplexed short tandem repeat (STR) assays used by the forensic human-identity community require tight control
of the initial amount of sample DNA amplified in the polymerase chain reaction (PCR) process. This, in turn, requires the
ability to reproducibly measure the concentration of human DNA, [DNA], in a sample extract. Quantitative PCR (qPCR) techniques
can determine the number of intact stretches of DNA of specified nucleotide sequence in an extremely small sample; however,
these assays must be calibrated with DNA extracts of well-characterized and stable composition. By 2004, studies coordinated
by or reported to the National Institute of Standards and Technology (NIST) indicated that a well-characterized, stable human
DNA quantitation certified reference material (CRM) could help the forensic community reduce within- and among-laboratory
quantitation variability. To ensure that the stability of such a quantitation standard can be monitored and that, if and when
required, equivalent replacement materials can be prepared, a measurement of some stable quantity directly related to [DNA]
is required. Using a long-established conventional relationship linking optical density (properly designated as decadic attenuance)
at 260 nm with [DNA] in aqueous solution, NIST Standard Reference Material (SRM) 2372 Human DNA Quantitation Standard was
issued in October 2007. This SRM consists of three quite different DNA extracts: a single-source male, a multiple-source female,
and a mixture of male and female sources. All three SRM components have very similar optical densities, and thus very similar
conventional [DNA]. The materials perform very similarly in several widely used gender-neutral assays, demonstrating that
the combination of appropriate preparation methods and metrologically sound spectrophotometric measurements enables the preparation
and certification of quantitation [DNA] standards that are both maintainable and of practical utility.
Figure NIST Standard Reference Material (SRM) 2372 Human Quantitation Standard 相似文献
94.
95.
J.M. Kline S.S. Penner 《Journal of Quantitative Spectroscopy & Radiative Transfer》1980,24(3):185-189
We describe the measurement of an off-peak spectral absorption coefficient for an isolated spectral line using a laser light source. This type of experiment may be used to determine the following line parameters: the line strength (S), the collision-broadened half-widths for self-broadening (b0c,F and for inert-gas broadening (b0c, I) per unit pressure, and the displacement of the laser frequency from the line center (Δω). The theoretical relations have been applied to absorption measurements on formaldehyde using an HeXe laser light source at 3.508 μ. 相似文献
96.
Kline JL Montgomery DS Bezzerides B Cobble JA DuBois DF Johnson RP Rose HA Yin L Vu HX 《Physical review letters》2005,94(17):175003
Thomson scattering is used to measure Langmuir waves (LW) driven by stimulated Raman scattering (SRS) in a diffraction limited laser focal spot. For SRS at wave numbers klambda(D) less similar 0.29, where k is the LW number and lambda(D) is the Debye length, multiple waves are detected and are attributed to the Langmuir decay instability (LDI) driven by the primary LW. At klambda(D) greater similar 0.29, a single wave, frequency-broadened spectrum is observed. The transition from the fluid to the kinetic regime is qualitatively consistent with particle-in-cell simulations and crossing of the LDI amplitude threshold above that for LW self-focusing. 相似文献
97.
J. Billiter K. Bennewitz N. Bjerrum N. E. Loomis S. F. Acree C. N. Murray G. M. Kline M. R. Meacham Florence Fenwick Fr. L. Hahn M. Frommer I. Lifschitz M. Reggiani D. A. Mc Innes M. Dole C. W. Foulk M. Hollingsworth L. R. Parks H. C. Beard K. W. Franke J. J. Willaman Lava Hemedes H. T. S. Britton R. A. Robinson W. H. Harrison P. N. Vridhachalam J. J. Shukoff G. P. Awsejewitsch L. W. Elder Jr. P. Jolibois G. Fouretier P. Dubois H. A. Bromley L. W. Causer A. de Waele T. Callan S. Horrobin R. J. Fosbinder E. H. Ducloux 《Analytical and bioanalytical chemistry》1932,90(11-12):432-443
98.
A sensitive high-performance liquid chromatographic (HPLC) assay for the determination of the cyclic heptapeptide Ac-Cs-Asn-Dtc-Amf-Gly-Asp-Cys-OH (Dtc = beta,beta-dimethylthioproline, Amf = p-aminomethylphenylalanine) in human plasma has been developed. The key steps in the assay include: solid-phase extraction of the drug from plasma, chemical derivatization of the primary amino group with naphthalene-2,3-dicarboxyaldehyde in the presence of N-acetyl-D-penicillamine as a nucleophile to form a fluorescent benzo[f]isoindole derivative, and HPLC with column switching to provide the necessary chromatographic separation of the derivative from endogenous plasma components. The assay has been validated in the concentration range 1-10 ng/ml of plasma. 相似文献
99.
McElhanon JR Zifer T Kline SR Wheeler DR Loy DA Jamison GM Long TM Rahimian K Simmons BA 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3259-3266
Two new surfactant molecules are reported that contain thermally labile Diels-Alder adducts connecting the hydrophilic and hydrophobic sections of each molecule. The two surfactants possess identical hydrophobic dodecyl tail segments but have phenol and carboxylic acid hydrophilic headgroups, respectively. Deprotonation with potassium hydroxide affords the formation of water-soluble surfactants. Room temperature aqueous solutions of both surfactants exhibit classical surface-active agent behavior similar to common analagous alkylaryl surfactant molecules. Critical micelle concentrations have been determined for each surfactant through dynamic surface tension and dye solubilization techniques. Small-angle neutron scattering measurements of the aqueous surfactant solutions indicate the presence of spherical micelles with radii of 16.5 angstroms for the carboxylate and 18.8 angstroms for the phenolate. When these surfactants are exposed to elevated temperatures (>50 degrees C), the retro Diels-Alder reaction occurs, yielding hydrophilic and hydrophobic fragments. Aqueous solutions of each surfactant subsequently exhibit a loss of all surface-active behavior and the micellar aggregates are no longer detectable. 相似文献
100.
A novel method for the determination of the relative stereochemistry of six-membered chairlike ring molecules by residual dipolar couplings is presented. C-H residual dipolar couplings were used to investigate the relative stereochemistry of 4,6-O-ethylidene-d-glucopyranose. For this and similar systems it is not necessary to acquire redundant dipolar couplings and to calculate the orientation order tensor. The presented methodology is a paradigmatic leap for the determination of the relative stereochemistry or remote stereochemistry in this kind of fused ring system. Residual dipolar coupling data were collected by 1D and 2D direct-measurement heteronuclear multiple quantum coherence (HMQC) spectroscopy. It was demonstrated that direct measurement of HMQC was quick and accurate for small molecules at natural abundance. 相似文献