Clay ratio as a tracer to assess the origin of soil-derived dust

IEECAS SKLLQG

Exploring the Origin of Power Law Distribution in Single-Molecule Conformation Dynamics: Energy Landscape Perspectives

We explored the origin of power law distribution observed in single-molecule conformational dynamics experiments. By establishing a kinetic master equation approach to study statistically the microscopic state dynamics, we show that the underlying landscape with exponentially distributed density of states leads to power law distribution of kinetics. The exponential density of states emerges when the system becomes glassy and landscape becomes rough with significant trapping.

Origin of negative differential resistance and memory characteristics in organic devices based on tris(8-hydroxyquinoline) aluminum

Negative differential resistance (NDR) and memory phenomenon have been realized in current-voltage (I-V) characteristics of indium tin oxide/tris(8-hydroxyquinoline) aluminum/aluminum devices. The I-V curves have been divided into three operational regions that are associated with different working regimes of the devices: (i) bistable region, (ii) NDR region, and (iii) monotonic region. The bistable region disappeared after a couple of voltage sweeps from zero to a positive voltage. The bistable nature can be reinstated by applying a suitable negative voltage.

Origin of improvement in device performance via the modification role of cesium hydroxide doped tris(8-hydroxyquinoline) aluminum interfacial layer on ITO cathode in inverted bottom-emission organic light-emitting diodes

It has been found that cesium hydroxide (CsOH) doped tris(8-hydroxyquinoline) aluminum (Alq(3)) as an interfacial modification layer on indium-tin-oxide (ITO) is an effective cathode structure in inverted bottom-emission organic light-emitting diodes (IBOLEDs). The efficiency and high temperature stability of IBOLEDs with CsOH:Alq(3) interfacial layer are greatly improved with respect to the IBOLEDs with the case of Cs2CO3:Alq(3). Herein, we have studied the origin of the improvement in efficiency and high temperature stability via the modification role of CsOH:Alq(3) interfacial layer on ITO cathode in IBOLEDs by various characterization methods, including atomic force microscopy (AFM), ultraviolet photoemission spectroscopy (UPS), X-ray photoemission spectroscopy (XPS) and capacitance versus voltage (C-V). The results clearly demonstrate that the CsOH:Alq(3) interfacial modification layer on ITO cathode not only enhances the stability of the cathode interface and electron-transporting layer above it. which are in favor of the improvement in device stability, but also reduces the electron injection barrier and increases the carrier density for current conduction, leading to higher efficiency.

Study on the origin of inverted phase in drying solution-cast block copolymer films

In a previous study, we reported observation of the novel inverted phase (the minority blocks comprising the continuum phase) in kinetically controlled phase separating solution-cast poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymer films [Zhang et al. Macromolecules 2000, 33, 9561-7]. In this study, we adopt the same approach to investigate the formation of inverted phase in a series of solution-cast poly(styrene-b-butadiene) (SB) asymmetric diblock copolymers having nearly equal polystyrene (PS) weight fraction (about 30 wt %) but different molecular weights. The microstructure of the solution-cast block copolymer films resulting from different solvent evaporation rates, R, was inspected, from which the kinetically frozen-in phase structures at qualitatively different block copolymer concentrations and correspondingly different effective interaction parameter, chieff, can be deduced. Our result shows that there is a threshold molecular weight or range of molecular weight below which the unusual inverted phase is accessible by controlling the solvent evaporation rate. In comparing the present result with that of our previous study on the SBS triblock copolymer, we find that the formation of the inverted phase has little bearing on the chain architecture. We performed numerical calculations for the free energy of block copolymer cylinders and found that the normal phase is always preferred irrespective of the interaction parameter and molecular weight, which suggests the formation of the inverted phase to have a kinetic origin.

The origin of nonlinearities in K[B5O6(OH)(4)]center dot 2H(2)O crystal

In this paper the origin of nonlinearities of the K[B5O6(OH)(4)].2H(2)O(KB5) crystal has been investigated from a comprehensive view-point by using the bond-valence theory of complex crystals. The results of the calculation (d(31) = -1.18 X 10(-10) esu, d(32) = 0.20 X 10(-10) and d(33) = -1.03 X 10(-9) esu) are in good agreement with experimental data. For the first time we pointed out that its nonlinearities come from the H(2)-O(2) bonds and the [B5O6(OH)(4)](-) group, and estimated its larger nonlinear optical (NLO) coefficient d(33).

The origin of nonlinearity in KTiOPO4

The origin of nonlinearity in KTiOPO4 was investigated quantitatively from the chemical bond viewpoint. All constituent chemical bonds in this crystal were considered and their contributions to the total linearity and nonlinearity were quantitatively determined. Calculated results agree satisfactorily with experimental data in both signs and numerical values. These results show us that TiO6 groups and P(1)O-4 groups have relatively larger linear contributions and the nonlinearity derives from KOx (x=8,9) groups and P(2)O-4 groups. (C) 1997 American Institute of Physics.

Origin, development and evolutionary model of shelf desertization environment in late stage of Upper Pleistocene

Based on the study of palaeo-environmental evolution in the shelves of the Eastern China Seas, the concept of ''shelf desertization'' in the late stage of Upper Pleistocene is defined; the environmental background and evolutionary process of shelf desertization are analysed. Study on the records of subbottom profiling and the data of core samples from shelf areas revealed that during low sea-level stages, the sedimentary environment in the exposed shelf plains was dominated by aeolian depositional process under cold and dry climatic conditions, i.e. under the action of strong winter-monsoon winds. Parts of the exposed marine strata were disintegrated, and aeolian sand dunes were formed on the disintegrated marine deposits, from which the finer sediment grains were blown away by wind and deposited in the downwind areas to form the derivative loess deposits. Thus a desertization environmental system was formed in the exposed shelf plains of the Eastern China Seas.

Origin of a native sulfur chimney in the Kueishantao hydrothermal field, offshore northeast Taiwan

Analyses of rare earth and trace element concentrations of native sulfur samples from the Kueishantao hydrothermal field were performed at the Seafloor Hydrothermal Activity Laboratory of the Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences. Using an Elan DRC II ICP-MS, and combining the sulfur isotopic compositions of native sulfur samples, we studied the sources and formation of a native sulfur chimney. The results show, when comparing them with native sulfur from crater lakes and other volcanic areas, that the native sulfur content of this chimney is very high (99.96%), the rare earth element (REE) and trace element constituents of the chimney are very low (Sigma REE < 21x10(-9)), and the chondrite-normalized REE patterns of the native sulfur samples are similar to those of the Kueishantao andesite, implying that the interaction of subseafloor fluid-andesite at the Kueishantao hydrothermal field was of short duration. The sulfur isotopic compositions of the native sulfur samples reveal that the sulfur of the chimney, from H2S and SO2, originated by magmatic degassing and that the REEs and trace elements are mostly from the Kueishantao andesite and partly from seawater. Combining these results with an analysis of the thermodynamics, it is clear that from the relatively low temperature (< 116 degrees C), the oxygenated and acidic environment is favorable for formation of this native sulfur chimney in the Kueishantao hydrothermal field.

Origin and Pathway of Equatorial 13 degrees C Water in the Pacific Identified by a Simulated Passive Tracer and Its Adjoint

The origin and pathway of the thermostad water in the eastern equatorial Pacific Ocean, often referred to as the equatorial 13 degrees C Water, are investigated using a simulated passive tracer and its adjoint, based on circulation estimates of a global general circulation model. Results demonstrate that the source region of the 13 degrees C Water lies well outside the tropics. In the South Pacific, some 13 degrees C Water is formed northeast of New Zealand, confirming an earlier hypothesis on the water's origin. The South Pacific origin of the 13 degrees C Water is also related to the formation of the Eastern Subtropical Mode Water (ESTMW) and the Sub-Antarctic Mode Water (SAMW). The portion of the ESTMW and SAMW that eventually enters the density range of the 13 degrees C Water (25.8 < sigma(theta) < 26.6 kg m(-3)) does so largely by mixing. Water formed in the subtropics enters the equatorial region predominantly through the western boundary, while its interior transport is relatively small. The fresher North Pacific ESTMW and Central Mode Water (CMW) are also important sources of the 13 degrees C Water. The ratio of the southern versus the northern origins of the water mass is about 2 to 1 and tends to increase with time elapsed from its origin. Of the total volume of initially tracer-tagged water in the eastern equatorial Pacific, approximately 47.5% originates from depths above sigma(theta) = 25.8 kg m(-3) and 34.6% from depths below sigma(theta) = 26.6 kg m(-3), indicative of a dramatic impact of mixing on the route of subtropical water to becoming the 13 degrees C Water. Still only a small portion of the water formed in the subtropics reaches the equatorial region, because most of the water is trapped and recirculates in the subtropical gyre.