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61.
Hassan Bassereh Vahid Salari Farhad Shahbazi Tapio Ala-Nissila 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(6):111
We consider quantum excitation energy transport (EET) in a network of two-state nodes in the Markovian approximation by employing the Lindblad formulation. We find that EET from an initial site, where the excitation is inserted to the sink, is generally inefficient due to the inhibition of transport by localization of the excitation wave packet in a symmetric, fully-connected network. We demonstrate that the EET efficiency can be significantly increased up to ≈100% by perturbing hopping transport between the initial node and the one connected directly to the sink, while the rate of energy transport is highest at a finite value of the hopping parameter. We also show that prohibiting hopping between the other nodes which are not directly linked to the sink does not improve the efficiency. We show that external dephasing noise in the network plays a constructive role for EET in the presence of localization in the network, while in the absence of localization it reduces the efficiency of EET. We also consider the influence of off-diagonal disorder in the hopping parameters of the network. 相似文献
62.
A clean-up method was developed to enable the determination of tri-decabrominated diphenyl ethers, isomer-specific hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), (2-ethylhexyl)tetrabromobenzoate (TBB), and bis(2-ethylhexyl)tetrabromophthalate (TBPH) in the same dust sample extract using reasonable amounts of solvents and without dividing the sample. After extraction, the sample was separated on a silica column into three fractions that were subsequently cleaned up individually. The polybrominated diphenyl ethers (PBDEs) and DBDPE were eluted in Fraction I, TBB, TBPH, and BTBPE in Fraction II, and HBCDs in Fraction III. Fractions I and II were analyzed using gas chromatography/mass spectrometry and Fraction III using liquid chromatography/mass spectrometry. The method gave good recoveries (60-120%), precise results using (13)?C-labelled internal standards and was accurate when comparing results to certified values (PBDEs in NIST SRM 2585). The method was applied to dust samples from the Stockholm (Sweden) area. All the emerging brominated flame retardants (BFRs) studied, except BTBPE, were present in all the samples in quantifiable concentrations, often higher than the PBDEs. BTBPE was quantified in only one sample. It is evident that emerging BFRs are present in Swedish homes, and these compounds should be included in the BFR analyses of indoor environments. 相似文献
63.
Tapio Rajala 《Journal of Functional Analysis》2012,263(4):896-924
We construct geodesics in the Wasserstein space of probability measures along which all the measures have an upper bound on their density that is determined by the densities of the endpoints of the geodesic. Using these geodesics we show that a local Poincaré inequality and the measure contraction property follow from the Ricci curvature bounds defined by Sturm. We also show for a large class of convex functionals that a local Poincaré inequality is implied by the weak displacement convexity of the functional. 相似文献
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Gunnar Brinkmalm Erik Portelius Annika Öhrfelt Niklas Mattsson Rita Persson Mikael K. Gustavsson Charles H. Vite Johan Gobom Jan‐Eric Månsson Jonas Nilsson Adnan Halim Göran Larson Ulla Rüetschi Henrik Zetterberg Kaj Blennow Ann Brinkmalm 《Journal of mass spectrometry : JMS》2012,47(5):591-603
Amyloid precursor protein (APP) is the precursor protein to amyloid β (Aβ), the main constituent of senile plaques in Alzheimer's disease (AD). Endogenous Aβ peptides reflect the APP processing, and greater knowledge of different APP degradation pathways is important to understand the mechanism underlying AD pathology. When one analyzes longer Aβ peptides by low‐energy collision‐induced dissociation tandem mass spectrometry (MS/MS), mainly long b‐fragments are observed, limiting the possibility to determine variations such as amino acid variants or post‐translational modifications (PTMs) within the N‐terminal half of the peptide. However, by using electron capture dissociation (ECD), we obtained a more comprehensive sequence coverage for several APP/Aβ peptide species, thus enabling a deeper characterization of possible variants and PTMs. Abnormal APP/Aβ processing has also been described in the lysosomal storage disease Niemann–Pick type C and the major large animal used for studying this disease is cat. By ECD MS/MS, a substitution of Asp7 → Glu in cat Aβ was identified. Further, sialylated core 1 like O‐glycans at Tyr10, recently discovered in human Aβ (a previously unknown glycosylation type), were identified also in cat cerebrospinal fluid (CSF). It is therefore likely that this unusual type of glycosylation is common for (at least) species belonging to the magnorder Boreoeutheria. We here describe a detailed characterization of endogenous APP/Aβ peptide species in CSF by using an online top‐down MS‐based method. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
66.
Catalytic conversion of carbohydrates into value-added products and platform chemicals became a trend in recent years. Microwave activation used in the processes of carbohydrate conversion coupled with the proper choice of catalysts makes it possible to enhance dramatically the efficiency and sometimes the selectivity of catalysts. This mini-review presents a brief literature survey related to state-of-the-art methods developed recently by the world research community to solve the problem of rational conversion of carbohydrates, mostly produced from natural resources and wastes (forestry and agriculture wastes) including production of hydrogen, synthesis gas, furanics, and alcohols. The focus is made on microwave technologies used for processing carbohydrates. Of particular interest is the use of heterogeneous catalysts and hybrid materials in processing carbohydrates. 相似文献
67.
Andreas Bernas Birgitta Peltopakka Päivi Mäki-Arvela Kari Eränen Tapio Salmi Dmitry Yu. Murzin 《Research on Chemical Intermediates》2007,33(7):645-654
Dimethoxyborane was prepared by the reaction of trimethoxyboroxine, sodium borohydride and trimethyl borate in diethylene
glycol dimethyl ether solvent at 70°C under atmospheric pressure followed by distillation to increase the purity and analyzed
in liquid phase by FT-IR. The concentration of dimethoxyborane was identified by hydrolysis with water, which yields boric
acid, methanol and hydrogen, whereas the generated hydrogen was analyzed by the mass detector of a volumetric flow apparatus.
The FT-IR absorbance peak area showed a linear dependence on dimethoxyborane concentration in the wavenumber range 873 to
950 cm−1 for samples with dimethoxyborane concentrations 0 to 6.2 wt% in trimethyl borate. Data fitting using the least square method
gave an R
2 value of 97%. 相似文献
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