Affinity and Specificity of Levamlodipine-Human Serum Albumin Interactions: Insights into Its Carrier Function

The affinity and specificity of drugs with human serum albumin (HSA) are crucial factors influencing the bioactivity of drugs. To gain insight into the carrier function of HSA, the binding of levamlodipine with HSA has been investigated as a model system by a combined experimental and theoretical/computational approach. The fluorescence properties of HSA and the binding parameters of levamlodipine indicate that the binding is characterized by one binding site with static quenching mechanism, which is related to the energy transfer. As indicated by the thermodynamic analysis, hydrophobic interaction is the predominant force in levamiodipine-HSA complex, which is in agreement with the computational results. And the hydrogen bonds can be confirmed by computational approach between levamlodipine and HSA. Compared to predicted binding energies and binding energy spectra at seven sites on HSA, levamlodipine binding HSA at site I has a high affinity regime and the highest specificity characterized by the largest intrinsic specificity ratio (ISR). The binding characteristics at site I guarantee that drugs can be carried and released from HSA to carry out their specific bioactivity.

Rational Design, Synthesis, and Optical Properties of Film-Forming, Near-Infrared Absorbing, and Fluorescent Chiromophores with Multidonors and Large Heterocyclic Acceptors

A new series of film-forming, low-bandgap chromophores (1a,b and 2a,b) were rationally designed with aid of a computational study., and then synthesized and characterized. To realize absorption and emission above the 1000 nm wavelength, the molecular design focuses on lowering the LUMO level by fusing common heterocyclic units into a large conjugated core that acts an electron acceptor and increasing the charge transfer by attaching the multiple electron-donating groups at the appropriate positions of the acceptor core. The chromophores have bandgap levels of 1.27-0.71 eV, and accordingly absorb at 746-1003 nm and emit at 1035-1290 nm in solution. By design, the relatively high molecular weight (up to 2400 g mol(-1)) and non-coplanar structure allow these near-infrared (NIR) chromophores to be readily spin-coated as uniform thin films and doped with other organic semiconductors for potential device applications. Doping with [6,6]-phenyl-C-61 butyric acid methyl ester leads to a red shift in the absorption on]), for la and 2a. An interesting NIR electrochromism was found for 2a, with absorption being turned on at 1034 nm when electrochemically switched (at 1000 mV) from its neutral state to a radical cation state. Furthermore, a large Stokes shift (256-318 nm) is also unique for this multidonor-acceptor type of chromophore.

Substitution effect of nitrogen atoms with carbon atoms in porphyrin on the electronic structure and excited states properties

Density functional theory (DFT) electronic structure calculations were carried out to predict the structures and the absorption and emission spectra for porphyrin and a series of carbaporphyrins-carbaporphyrin, adj-dicarbaporphyrin, opp-dicarbaporphyrin, tricarbaporphyrin and tetracarbaporphyrin. The ground- and excited-state geometries were optimized at the B3LYP/6-31g(d) and CIS/6-31g(d) level, respectively. The optimized ground-state geometry and absorption spectra of porphyrin, calculated by DFT and time-dependent DFT (TDDFT), are comparable with the available experimental values. Based on the optimized excited-state geometries obtained by CIS/6-31g(d) method, the emission properties are calculated using TDDFT method at the B3LYP/6-31g(d) level. The effects of the substitution of nitrogen atoms with carbon atoms at the center positions of porphyrin are discussed. The results indicate that the two-pyrrole nitrogens are important to the chemical and physical properties for porphyrin.

Synthesis and crystal structure of [Nd(eta(6)-1,3,5-C6H3Me3)(AlCl4)(3)]( C6H6) and structural comparison of Ln(eta(6)-arene)(AlCl4)(3)

Reaction of NdCl3, with AlCl3 and mesitylene in benzene gives complex [Nd(eta (6)-1,3,5-C6H3Me3) (AlCl4)(3)] (C6H6) (1) which was characterized by elemental analysis, IR spectra, MS and X-lay diffractions. The X-ray determination indicates that 1 has a distorted pentagonal bipyramidal geometry and crystallizes in the monoclinic, space group P2(1)/n with a = 0.9586(2), b = 1.1717(5), c = 2.8966(7) nm, beta = 90.85 (2)degrees, V = 3.2529(6) nm(3), D-c = 1.573 g/cm(3), Z = 4. A comparison of bond parameters for all the reported Ln(eta (6)-Ar) (AlCl4)(3) complexes indicates that the bond distance of Ln-C is shortened with the increasing of methyl group on benzene and with the decreasing of radius of lanthanide ions.

Geophysical signatures associated with fluid flow and gas hydrate occurrence in a tectonically quiescent sequence, Qiongdongnan Basin, South China Sea

Interpretation of high-resolution two-dimensional (2D) and three-dimensional (3D) seismic data collected in the Qiongdongnan Basin, South China Sea reveals the presence of polygonal faults, pockmarks, gas chimneys and slope failure in strata of Pliocene and younger age. The gas chimneys are characterized by low-amplitude reflections, acoustic turbidity and low P-wave velocity indicating fluid expulsion pathways. Coherence time slices show that the polygonal faults are restricted to sediments with moderate-amplitude, continuous reflections. Gas hydrates are identified in seismic data by the presence of bottom simulating reflectors (BSRs), which have high amplitude, reverse polarity and are subparallel to seafloor. Mud diapirism and mounded structures have variable geometry and a great diversity regarding the origin of the fluid and the parent beds. The gas chimneys, mud diapirism, polygonal faults and a seismic facies-change facilitate the upward migration of thermogenic fluids from underlying sediments. Fluids can be temporarily trapped below the gas hydrate stability zone, but fluid advection may cause gas hydrate dissociation and affect the thickness of gas hydrate zone. The fluid accumulation leads to the generation of excess pore fluids that release along faults, forming pockmarks and mud volcanoes on the seafloor. These features are indicators of fluid flow in a tectonically-quiescent sequence, Qiongdongnan Basin. Geofluids (2010) 10, 351-368.

Influence of mean water depth and a subsurface sandbar on the onset and strength of wave breaking

Wave breaking in the open ocean and coastal zones remains an intriguing yet incompletely understood process, with a strong observed association with wave groups. Recent numerical study of the evolution of fully nonlinear, two-dimensional deep water wave groups identified a robust threshold of a diagnostic growth-rate parameter that separated nonlinear wave groups that evolved to breaking from those that evolved with recurrence. This paper investigates whether these deep water wave-breaking results apply more generally, particularly in finite-water-depth conditions. For unforced nonlinear wave groups in intermediate water depths over a flat bottom, it was found that the upper bound of the diagnostic growth-rate threshold parameter established for deep water wave groups is also applicable in intermediate water depths, given by k(0) h greater than or equal to 2, where k(0) is the mean carrier wavenumber and h is the mean depth. For breaking onset over an idealized circular arc sandbar located on an otherwise flat, intermediate-depth (k(0) h greater than or equal to 2) environment, the deep water breaking diagnostic growth rate was found to be applicable provided that the height of the sandbar is less than one-quarter of the ambient mean water depth. Thus, for this range of intermediate-depth conditions, these two classes of bottom topography modify only marginally the diagnostic growth rate found for deep water waves. However, when intermediate-depth wave groups ( k(0) h greater than or equal to 2) shoal over a sandbar whose height exceeds one-half of the ambient water depth, the waves can steepen significantly without breaking. In such cases, the breaking threshold level and the maximum of the diagnostic growth rate increase systematically with the height of the sandbar. Also, the dimensions and position of the sandbar influenced the evolution and breaking threshold of wave groups. For sufficiently high sandbars, the effects of bottom topography can induce additional nonlinearity into the wave field geometry and associated dynamics that modifies the otherwise robust deep water breaking-threshold results.

东营凹陷成藏组合体研究与勘探实践

With the development of petroleum exploration, subtle reservoir has become the main exploration object in Dongying Depression, which requires some new technologies and methods to further reveal the geological characteristics in step with the mature exploration stage. In this paper, on the references to the studies of petroleum system and multiple oil-gas accumulation belt with flexible maneuverability, and the application of systematic theory, the concept of reservoir assemblage is initially defined as "the association of active source rock(s) and hydrocarbon reservoir(s) that are genetically related, with the bridge of pathway system in an oil and gas bearing basin". Compared with the theories of petroleum system and multiple oil-gas accumulation belts, it emphasizes on the processes of petroleum migration and accumulation and the correlation among active source rock, trapped hydrocarbon and migration pathway, and has been confirmed to be more suitably applied to high maturely explored basin. In the first study of this paper, sequence stratigraphy and subtle analytical technology of source rock have been employed to find that two categories of source rock with their characteristic types of organic matter and substantial states occurred in Dongying Depression. The first category, consisting of the oil shales within the third-order sequences of lacustrine expanding system tracts in the upper interval of the fourth Member of Shahejie Formation and both in the middle and lower intervals of the third Member of Shahejie Formation, is featured with the highest abundance of total organic matter (TOC) and the strongest abilities of hydrocarbon generation and expulsion, which is classified into the standard of good hydrocarbon source rock. Exploration assessment confirmed that about 70-80% of hydrocarbon in Dongying Depression came from this set of source rock for which the low sedimentary rate and strong oxygen-free environment would play the key role during its generation. The second category, composed of organic matter of dark mudstone in high stand system tracts in the upper and middle intervals of the third Member of Shahejie Formation, has been characterized by low content of total organic matter which mostly dispersedly distributes, and formed in the pre-delta to delta front environments. In classification, it belongs to the ordinary standard of source rocks. In the second research part, through the studies of high frequency sequence stratigraphy, fault geometry and active history combining with geochemistry of fluid inclusion and nitrogen compound and simulation test of hydrocarbon migration and accumulation, the faults have been thought to be the principal conduits, and the sandy bodies and unconformities might played the complementary pathways for hydrocarbon migration and accumulation in Dongying Depression of the continental faulted basin. Therefore, the fault activities may mainly constrain on the development of hydrocarbon pathways in space and time. Even more, using homogenization temperatures of fluid inclusion in digenetic minerals, three critical moments for hydrocarbon accumulation have been determined as well in Dongying Depression, which happened during the late stage of Dongying Formation (Ed), the early stage of Guantao Formation (Nig) and the early stage of Minghuazhen Formation (Nim), respectively. Comparatively, the last stage is looked as the main forming-reservoir period, which has also been supported by the results of geochemical analysis and simulation experiments of hydrocarbon generation and expulsion. Clearly, the times of hydrocarbon migration and accumulation are consistent with those of the fault activities in Dongying Depression, which indicate that tectonic activities would control the forming-reservoir. A conceptual model of faulting-episodic expulsion coupled with episodic forming-reservoir has then been established in this study. In the third part of this paper, some focusing areas were selected for the fine descriptions of pathway distribution and forming-reservoir, which has given four types of reservoir assemblage in terms of the main pathway and its correlation with the reservoir and trap: (1) mainly consisted of sandy bodies; (2) mainly consisted of faults; (3) mainly consisted of unconformities; and (4) their complex with two or three types of pathways. This classified criteria has also been applied to access the risk of some prospected traps in Dongying Depression. Finally, through the application of reservoir assemblage integrated with pathway distribution to all the prospective targets in Dongying Depression, the new favorably hydrocarbon accumulated belts have been figured out, and more subtle reservoirs have also been found. For examples, during 2000 and 2002, in the mature exploration areas, such as Liangjialou and Shengtuo structural closures etc., newly proved reserves were 2274 * 104t, and forecasted oil reserves 5660-5860xl04t; and in the predicted favorable areas, newly additional controlled oil reserves was 3355xl04t. Besides those, many other favorable exploration areas need to be further appraised.

库车坳陷-南天山盆山系统第三纪脆性构造研究

Study on the structural coupling relationship between basin and range is not only helpful to recognize the basin formation and evolution systematically, but also to guide petroleum exploration in the basin. As a late Paleozoic Orogen, the South Tianshan Mountains reactivated and uplifted rapidly during the Cenozoic, and led to the Mesozoic-Cenozoic considerable thick deposits in the Kuqa Depression. The researches of the dissertation were carried out in the Kuqa depression-South Tianshan M ountain s ystem, a nd t he b rittle m icrotectonics w. ere c hosen as t he m ost important object. Based on observations and measurements of the field, we made detailed investigations on the geometry and kinematics of this area, and analyzed the abutting and cutting relationships and relative sequence of many brittle structures, such as joint, shear fractures, faults and some small-scale structures related to them closely. According to those brittle fractures' relationships with stress, the nature and variation of regional palaeostress field during the Cenozoic were studied through inversion of fault slip data and inferring stress state from joint sequences. And the deformation time was estimated primarily via ESR dating of faulting. Results show that the stress field varies as well in times as in space. The maximal principal stress direction shifted from the vertical to the horizontal, and stress regime from weak extension to strong compression from the Paleogene to the Neogene regionally. During the late Neogene, the structural deformation of the South Tianshan and the basin-range boundary was dominated by near N-S extension, while near N-S compressive deformation in the interior of the Kuqa Depression. There exits obvious differential stress state from the north to the south. ESR dating of the faulting during the Cenozoic indicates that, the normal faulting in the north edge of the Kuqa Depression have been active all along from the Miocene to the early Pleistocene, but the thrusting and reverse faulting in the interior only been active from the Pliocene to the early Pleistocene. On the base of those geological data and some geophysical information and theoretical calculation results, we infer that, the different stress regime the basin-range system is ascribed to the vertical uplift of the Tianshan Mountain. It was the vertical uplift that lead to the gravity-driven gliding of thick layers lying on the faulted basement from the South Tianshan Mountain to the Kuqa depression, and to folding and thrusting in the interior and frontal of the Kuqa depression. Combining the structural evolution with petroleum geological conditions of the Kuqa Depression, we think that the strong compressive deformation of the Kuqa Depression during rapid uplifting of the Tianshan Mountains from the Pliocene to the early Pleistocene play crucial role in the structural trap formation and proliferous gas accumulation.

Tensor density matrix theory for determining population and alignment of symmetric top molecule using rotationally unresolved fluorescence

General expressions used for transforming raw laser-induced fluorescence (LIF) intensity into the population and alignment parameters of a symmetric top molecule are derived by employing the density matrix approach. The molecular population and alignment are described by molecular state multipoles. The results are presented for a general excitation-detection geometry and then applied to some special geometries. In general cases, the LIF intensity is a complex function of the initial molecular state multipoles, the dynamic factors and the excitation-detection geometrical factors. It contains a population and 14 alignment multipoles. How to extract all initial state multipoles from the rotationally unresolved emission LIF intensity is discussed in detail.

Fully developed laminar flow and heat transfer in smooth trapezoidal microchannel

Numerical analysis of fully developed laminar slip flow and heat transfer in trapezoidal micro-channels has been studied with uniform wall heat flux boundary conditions. Through coordinate transformation, the governing equations are transformed from physical plane to computational domain, and the resulting equations are solved by a finite-difference scheme. The influences of velocity slip and temperature jump on friction coefficient and Nusselt number are investigated in detail. The calculation also shows that the aspect ratio and base angle have significant effect on flow and heat transfer in trapezoidal micro-channel. (c) 2005 Elsevier Ltd. All rights reserved.