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71.
W. Muchlinsky E. Rother G. Jander O. Pfundt E. Göte W. Schramek L. W. Janssen J. A. C. Teegan A. Schleicher W. Lüdicke E. Denina J. M. Preston N. Rae J. K. Rummel K. Schierjott J. M. Kolthoff T. Kameda L. Blumen J. Pucherna Fr. Hein H. Pauling 《Analytical and bioanalytical chemistry》1932,89(3-4):128-135
72.
Crowther AC Carrier SL Preston TJ Crim FF 《The journal of physical chemistry. A》2008,112(47):12081-12089
Time-resolved studies using 100 fs laser pulses generate CN radicals photolytically in solution and probe their subsequent reaction with solvent molecules by monitoring both radical loss and product formation. The experiments follow the CN reactants by transient electronic spectroscopy at 400 nm and monitor the HCN products by transient vibrational spectroscopy near 3.07 microm. The observation that CN disappears more slowly than HCN appears shows that the two processes are decoupled kinetically and suggests that the CN radicals rapidly form two different types of complexes that have different reactivities. Electronic structure calculations find two bound complexes between CN and a typical solvent molecule (CH(2)Cl(2)) that are consistent with this picture. The more weakly bound complex is linear with CN bound to an H atom through the N atom, and the more strongly bound complex has a structure in which the CN bridges Cl and H atoms of the solvent. Fitting the transient absorption data with a kinetic model containing two uncoupled complexes reproduces the data for seven different chlorinated alkane solvents and yields rate constants for the reaction of each type of complex. Depending on the solvent, the linear complex reacts between 2.5 and 12 times faster than the bridging complex and is the primary source of the HCN reaction product. Increasing the Cl atom content of the solvents decreases the reaction rate for both complexes. 相似文献
73.
Herein we report our method of water solubilization and subsequent functionalization of a variety of nanoparticle systems with amphiphilic polymers containing build-in "chemical handles". We have used these polymers, which have narrow polydispersity indices, to impart water solubility and chemical sensitivity toward targeted species (here: pH). These material systems have high chemical conjugation efficiencies in aqueous conditions which may be used to create a variety of chemical and biological multifunctional materials. 相似文献
74.
75.
S. Neretina R. A. Hughes J. F. Britten N. V. Sochinskii J. S. Preston P. Mascher 《Applied Physics A: Materials Science & Processing》2009,96(2):429-433
The small lattice mismatch and sixfold symmetry offered by the (0001) planes of sapphire make it an ideal substrate candidate
for the deposition of (111) CdTe films. There, however, exists a wide disparity in film quality among various researchers
with both single crystal and highly twinned, multidomain films being reported. We have developed a pulsed laser deposition
process that enables us to deposit nearly single-domain (111) CdTe films exhibiting excellent surface morphology. Such films
are deposited on as-received sapphire substrates in vacuum conditions where oxygen is readily available. If, however, film
deposition is preceded by the deposition of a submonolayer of aluminum prior to film growth then a secondary CdTe domain emerges
with an in-plane orientation having a 180°-in-plane offset from the first domain. These multidomain films show poor crystallographic
and morphological properties, similar to what has been reported elsewhere. It is concluded that the singly terminated (0001)
sapphire substrates are a prerequisite for the deposition of high-quality (111) CdTe films. 相似文献
76.
Uriel Octavio Moreles Vázquez Wataru Shinoda Preston B. Moore Chi-cheng Chiu Steven O. Nielsen 《Journal of mathematical chemistry》2009,45(1):161-174
We discuss three topologically different methods for calculating the surface tension between a flat solid and a liquid from
theoretical and computer simulation viewpoints. The first method, commonly used in experiments, measures the contact angle
at which a static droplet of liquid rests on a solid surface. We present a new analysis algorithm for this method and explore
the effects of line tension on the contact angle. The second method, commonly used computer simulations, uses the pressure
tensor through the virial in a system where a thick, infinitely extended slab of liquid rests on a solid surface. The third
method, which is original to this paper and is closest to the thermodynamic definition of surface tension, applies to a spherical
solid in contact with liquid in which the flat solid is recovered by extrapolating the sphere radius to infinity. We find
that the second and third methods agree with each other, while the first method systematically underestimates surface tension
values. 相似文献
77.
The (13)C-mixed triacylglcerol (MTG, 1,3-distearyl, 2-[1-(13)C]octanoyl glycerol) breath test is a non-invasive measure of intraluminal fat digestion. Recovery of (13)C in breath CO(2) is incomplete (<50%) owing to sequestration of (13)C into organic molecules via the tricarboxylic acid (TCA) cycle. In addition lack of knowledge of CO(2) production rate (VCO(2)) during the test leads to errors in the calculated percentage dose recovered (PDR). (2)H sequestration into organic molecules is low ( approximately 4%) and is not influenced by factors that affect VCO(2) such as food intake or physical activity. After oxidation of (2)H-labelled macromolecules, the label appears in body water, which can be sampled non-invasively in urine or saliva. After an overnight fast, two healthy adults consumed [(2)H]MTG (1,3-distearyl, 2-[(2)H(15)]octanoyl glycerol) and [(13)C]MTG (1,3 distearyl, 2-[1-(13)C]octanoyl glycerol) simultaneously. Total body water (TBW) was measured by (18)O dilution and also estimated from height and weight. Urine and saliva were sampled at baseline and for 10 h after consumption of the test meal. The abundance of (2)HOH and H(2) (18)O in urine and saliva was measured by continuous-flow isotope-ratio mass spectrometry. Cumulative PDR of (2)H and (18)O was calculated from the plateau enrichment, which was reached by 6 h in both saliva and urine. Recovery of (2)H calculated using measured TBW was compared with that using an estimated value of TBW. Mean recovery of (2)H in saliva was 99.3% and in urine was 96.4%. Errors introduced by estimating TBW were <5%. [(2)H]MTG could provide a simpler, more robust, indirect test of intraluminal fat digestion compared with the (13)C-breath test. Further studies are required in pancreatic insufficient patients. 相似文献
78.
Brouard M Cireasa R Clark AP Preston TJ Vallance C 《The Journal of chemical physics》2006,124(6):64309
Velocity-map ion imaging has been applied to the photodissociation of NO(2) via the first absorption band at 308 nm using (2 + 1) resonantly enhanced multiphoton ionization detection of the atomic O((3)P(J)) products. The resulting ion images have been analyzed to provide information about the speed distribution of the O((3)P(J)) products, the translational anisotropy, and the electronic angular momentum alignment. The atomic speed distributions were used to provide information about the internal quantum-state distribution in the NO coproducts. The data were found to be consistent with an inverted NO vibrational quantum-state distribution, and thereby point to a dynamical, as opposed to a statistical dissociation mechanism subsequent to photodissociation at 308 nm. Surprisingly, at this wavelength the O-atom electronic angular momentum alignment was found to be small. Probe-only ion images obtained under a variety of molecular-beam backing-pressure conditions, and corresponding to O atoms generated in the photodissociation of either the monomer, NO(2), or the dimer, N(2)O(4), at 226 nm, are also reported. For the monomer, where 226 nm corresponds to excitation into the second absorption band, the kinetic-energy release distributions are also found to indicate a strong population inversion in the NO cofragment, and are shown to be remarkably similar to those previously observed in the wavelength range of 193-248 nm. Mechanistic implications of this result are discussed. At 226 nm it has also been possible to observe directly O atoms from the photodissociation of the dimer. The O-atom velocity distribution has been analyzed to provide information about its production mechanism. 相似文献
79.
PD McCrary PA Beasley SP Kelley S Schneider JA Boatz TW Hawkins JP Perez BW McMahon M Pfiel SF Son SL Anderson RD Rogers 《Physical chemistry chemical physics : PCCP》2012,14(38):13194-13198
The passivation and stability of suspensions of titanium nanoparticles in azolium azolate ionic liquids can be tuned by introducing metal specific binding sites in the azolate anion. 相似文献
80.
Theoretical approximations to the sum frequency vibrational spectroscopy (SFVS) of the carbon tetrachloride/water interface are constructed using the quantum-corrected time correlation functions (TCF) to aid in interpretation of experimental data and to predict novel vibrational modes. Instantaneous normal mode (INM) methods are used to characterize the observed modes leading to the TCF signal, thus providing molecular resolution of the vibrational lineshapes. Detailed comparisons of the theoretical signals are made with those obtained experimentally and show excellent agreement for the spectral peaks in the O-H stretching region of water. An intermolecular mode, unique to the interface, at 848 cm(-1) is also identifiable, similar to the one seen for the water/vapor interface. INM analysis reveals the resonance is due to a wagging mode (hindered rotation) that was previously identified (Perry et al 2005 J. Chem. Phys. 123 144705) as localized on a single water molecule with both hydrogens displaced normal to the interface-generally it is found that the symmetry breaking at the interface leads to hindered translations and rotations at hydrophilic/hydrophobic interfaces that assume finite vibrational frequencies due to anchoring at the aqueous interface. Additionally, examination of the real and imaginary parts of the theoretical SFVS spectra reveal the spectroscopic species attributed the resonances and possible subspecies in the O-H region; these results are consistent with extant experimental data and associated analysis. 相似文献