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91.
Fahlquist H Noréus D Callear S David WI Hauback BC 《Journal of the American Chemical Society》2011,133(37):14574-14577
The first examples of a new class of gallium hydride clusters with direct Ga-Ga bonds and common hydrocarbon structures are reported. Neutron powder diffraction was used to find a Ga[GaH(3)](4)(5-) cluster ion with a neopentane structure in a novel cubic structure type of Rb(8)Ga(5)H(15). Another cluster ion with a polyethylene structure, [GaH(2)](n)(n-), was found in a second novel (RbGaH(2))(n) hydride. These hydrocarbon-like clusters in gallium hydride materials have significant implications for the discovery of hydrides for hydrogen storage as well as for interesting electronic properties. 相似文献
92.
Including gravity and wettability effects, a full analytical solution for the frontal flow period for 1D counter-current spontaneous
imbibition of a wetting phase into a porous medium saturated initially with non-wetting phase at initial wetting phase saturation
is presented. The analytical solution applicable for liquid–liquid and liquid–gas systems is essentially valid for the cases
when the gravity forces are relatively large and before the wetting phase front hits the no-flow boundary in the capillary-dominated
regime. The new analytical solution free of any arbitrary parameters can also be utilized for predicting non-wetting phase
recovery by spontaneous imbibition. In addition, a new dimensionless time equation for predicting dimensionless distances
travelled by the wetting phase front versus dimensionless time is presented. Dimensionless distance travelled by the waterfront
versus time was calculated varying the non-wetting phase viscosity between 1 and 100 mPas. The new dimensionless time expression
was able to perfectly scale all these calculated dimensionless distance versus time responses into one single curve confirming
the ability for the new scaling equation to properly account for variations in non-wetting phase viscosities. The dimensionless
stabilization time, defined as the time at which the capillary forces are balanced by the gravity forces, was calculated to
be approximately 0.6. The full analytical solution was finally used to derive a new transfer function with application to
dual-porosity simulation. 相似文献
93.
A spectrally accurate fast method for electrostatic calculations under periodic boundary conditions is presented. We follow the established framework of FFT-based Ewald summation, but obtain a method with an important decoupling of errors: it is shown, for the proposed method, that the error due to frequency domain truncation can be separated from the approximation error added by the fast method. This has the significance that the truncation of the underlying Ewald sum prescribes the size of the grid used in the FFT-based fast method, which clearly is the minimal grid. Both errors are of exponential-squared order, and the latter can be controlled independently of the grid size. We compare numerically to the established SPME method by Essmann et al. and see that the memory required can be reduced by orders of magnitude. We also benchmark efficiency (i.e. error as a function of computing time) against the SPME method, which indicates that our method is competitive. Analytical error estimates are proven and used to select parameters with a great degree of reliability and ease. 相似文献
94.
Ine L. Jernelv Karolina Milenko Silje S. Fuglerud Dag Roar Hjelme Reinold Ellingsen Astrid Aksnes 《应用光谱学评论》2013,48(7):543-572
Frequent glucose monitoring is a fundamental part of diabetes management, and good glucose control is important for long-term health outcomes. New types of electrochemical sensors that allow for continuous glucose monitoring (CGM) have become an important tool for diabetes management, although they still have drawbacks such as short lifetime and a need for frequent calibration. Other technologies are still being researched for CGM, in an attempt to replace the electrochemical sensors. Optical methods have several advantages for CGM, including potentially long sensor lifetimes and short measurement times, and many developments have been made over the last decades. This paper will review optical measurement methods for CGM, their challenges, and the current research status. The different methods will be compared, and the future prospects for optical methods will be discussed. 相似文献
95.
Hakan Durmaz Aydan Dag Umit Tunca Gurkan Hizal 《Journal of polymer science. Part A, Polymer chemistry》2012,50(12):2406-2414
A novel amphiphilic miktoarm star polymer, polystyrene‐poly(ethylene glycol)‐poly(methyl methacrylate), bearing a pyrene group at the end of PS arm (Pyrene‐PS‐PEG‐PMMA) was successfully synthesized via combination of atom transfer radical polymerization and click chemistry. The structure and composition of the amphiphilic miktoarm star polymer were characterized by gel permeation chromatography and 1H NMR. The functionalization of multiwalled carbon nanotubes (MWCNTs) via “π–π” stacking interactions with pyrene‐PS‐PEG‐PMMA miktoarm star polymer was accomplished and the resulting polymer‐MWCNTs hybrid was analyzed by using 1H NMR, UV–vis, fluorescence spectroscopy, and thermal gravimetric analysis. The high‐resolution transmission electron microscopy and analytical techniques aforementioned confirmed that the noncovalent functionalization of MWCNT's with the amphiphilic miktoarm star polymer was successfully achieved. The MWCNT/pyrene‐PS‐PEG‐PMMA exhibited significant dispersion stability in common organic solvents such as dimethyl formamide, chloroform, and tetrahydrofuran. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
96.
Azidoferrocene (1), 1,1′-diazidoferrocene (2) and 1,1′-diisothiocyanatoferrocene (3) were subjected to reactions from the repertoire of “click” chemistry, with a view to applications in the post-functionalisation of self-assembled monolayers. The copper-catalysed 1,3-dipolar cycloaddition of 1 and FcCCH (Fc = ferrocenyl) afforded the expected 1,2,3-triazole derivative under anhydrous and anaerobic conditions. Analogous reactions also succeeded with 2 and RCCH (R = Ph, Fc). The Staudinger reaction of 2 with 1,1′-bis(diphenylphosphanyl)ferrocene (dppf) gave the expected bis(iminophosphoranyl)ferrocene in high yield. The nucleophilic addition of 2 equiv. of NHR2 (R = Et, iPr) to 3 afforded the corresponding thiourea derivative in quantitative yield. 相似文献
97.
Lehtonen JV Still DJ Rantanen VV Ekholm J Björklund D Iftikhar Z Huhtala M Repo S Jussila A Jaakkola J Pentikäinen O Nyrönen T Salminen T Gyllenberg M Johnson MS 《Journal of computer-aided molecular design》2004,18(6):401-419
BODIL is a molecular modeling environment geared to help the user to quickly identify key features of proteins critical to molecular recognition, especially (1) in drug discovery applications, and (2) to understand the structural basis for function. The program incorporates state-of-the-art graphics, sequence and structural alignment methods, among other capabilities needed in modern structure–function–drug target research. BODIL has a flexible design that allows on-the-fly incorporation of new modules, has intelligent memory management, and fast multi-view graphics. A beta version of BODIL and an accompanying tutorial are available at http://www.abo.fi/fak/mnf/bkf/research/johnson/bodil.html 相似文献
98.
Based on first-principles calculations we show that gold atoms can form both freestanding and tip-suspended chiral single-wall nanotubes composed of helical atomic strands. The freestanding, infinite (5,5) tube is found to be energetically the most favorable. While energetically less favorable, the experimentally observed (5,3) tube stretching between two tips corresponds to a local minimum in the string tension. Similarly, the (4,3) tube is predicted as a favorable structure yet to be observed experimentally. Analysis of band structure, charge density, and quantum ballistic conductance suggests that the current on these wires is less chiral than expected, and there is no direct correlation between the numbers of conduction channels and helical strands. 相似文献
99.
100.
Lee MH Sankey OF Björling T Moser D Noréus D Parker SF Häussermann U 《Inorganic chemistry》2007,46(17):6987-6991
The vibrational properties of the recently discovered aluminum hydrides SrAl2H2 and SrAlSiH have been investigated by means of inelastic neutron scattering (INS) and first-principles calculations. Both compounds contain Al-H units being part of a two-dimensional polyanionic layer, [(AlH)(AlH)]2- and [Si(AlH)]2-, respectively. The INS spectrum of SrAlSiH is characterized by very weakly dispersed Al-H modes with well-resolved overtones, while SrAl2H2 yields a solid-state dispersed phonon spectrum. The frequency of the stretching mode of the Al-H unit in SrAlSiH is the hitherto lowest observed for a terminal Al-H bond. At the same time, SrAlSiH displays the highest decomposition temperature known for an aluminum hydride compound. It is proposed that the stability of solid-state aluminum hydrides correlates inversely with the strength of Al-H bonding. 相似文献