Showing papers by "Tongji University published in 2004"

Identification of a KCNE2 Gain-of-Function Mutation in Patients with Familial Atrial Fibrillation

Abstract: Atrial fibrillation (AF) is the most common cardiac arrhythmia encountered in clinical practice. We first reported an S140G mutation of KCNQ1, an α subunit of potassium channels, in one Chinese kindred with AF. However, the molecular defects and cellular mechanisms in most patients with AF remain to be identified. We evaluated 28 unrelated Chinese kindreds with AF and sequenced eight genes of potassium channels (KCNQ1, HERG, KCNE1, KCNE2, KCNE3, KCNE4, KCNE5, and KCNJ2). An arginine-to-cysteine mutation at position 27 (R27C) of KCNE2, the β subunit of the KCNQ1-KCNE2 channel responsible for a background potassium current, was found in 2 of the 28 probands. The mutation was present in all affected members in the two kindreds and was absent in 462 healthy unrelated Chinese subjects. Similar to KCNQ1 S140G, the mutation had a gain-of-function effect on the KCNQ1-KCNE2 channel; unlike long QT syndrome–associated KCNE2 mutations, it did not alter HERG-KCNE2 current. The mutation did not alter the functions of the HCN channel family either. Thus, KCNE2 R27C is a gain-of-function mutation associated with the initiation and/or maintenance of AF.

Conductivity of carbon fiber reinforced cement-based composites

Abstract: The conductive behavior of carbon fiber cement-based composites is presented. The influence of carbon fiber volume, size, cement-based matrix, relative humidity and curing age on the characteristic of system were studied. The relationship between conductivity and volume fraction of carbon fiber indicated that the statistical percolation theory is suitable and applicable for the change rule of conductivity of system with the volume of carbon fiber. Based on the classic percolation theory, the percolation threshold of carbon fiber cement-based composites was determined as φ=φc2 and the conductive mechanism changes from electron tunneling conduction to ohmic contacting conduction. The studies have offered basic theory for smart cement-based composites.

Properties of one-dimensional photonic crystals containing single-negative materials.

Abstract: The transmission properties of a one-dimensional photonic crystal containing two kinds of single-negative (permittivity- or permeability-negative) media are studied theoretically. We show that this structure can possess a type of photonic gap with zero effective phase $({\ensuremath{\phi}}_{\text{eff}})$. The zero-${\ensuremath{\phi}}_{\text{eff}}$ gap distinguishes itself from a Bragg gap in that it is invariant with a change of scale length and is insensitive to thickness fluctuation. In contrast to a photonic gap corresponding to zero averaged refractive index, the zero-${\ensuremath{\phi}}_{\text{eff}}$ gap can be made very wide by varying the ratio of the thicknesses of two media. An equivalent transmission-line model is utilized to explain the properties. A photonic quantum-well structure based on zero-${\ensuremath{\phi}}_{\text{eff}}$ gaps is proposed as a multiple channeled filter that is compact and robust against disorder.

Cement‐Based 0‐3 Piezoelectric Composites

Abstract: To meet the requirements of development for smart or intelligent structures in civil engineering, new functional materials that have good compatibility with civil engineering structural materials are needed. In this study, for the first time in the field of piezoelectric materials, cement-based 0-3 piezoelectric (PZT) composites were fabricated by the normal mixing and spreading method. The new materials have very good compatibility with portland cement concrete. The cement-based 0-3 piezoelectric composites were shown to have a slightly higher piezoelectric factor and electromechanical coefficient than those of 0-3 PZT/polymer composites with a similar content of PZT particles; thus, they are adequate for sensor application. There is potential for the application of cement-based 0-3 PZT composites in civil engineering because of their better piezoelectric properties and good compatibility with portland cement concrete.

Omnidirectional gap and defect mode of one-dimensional photonic crystals with single-negative materials

Abstract: A new type of omnidirectional gaps is theoretically found in one-dimensional photonic crystals (1DPCs) composed of two kinds of single-negative (SNG) (permittivity- or permeability-negative) materials. In contrast to the Bragg gaps, the properties (the central frequency and width of the gap) of such omnidirectional gaps are insensitive to the incident angles and the light polarizations, and are invariant upon the change of scale length. Such omnidirectional gaps result from the interaction of evanescent waves. When a defect layer is introduced, a defect mode appears inside the omnidirectional gap, and the spectral position of the defect mode is almost independent of incident angles and nearly invariant with the scaling.

Probability density evolution method for dynamic response analysis of structures with uncertain parameters

Abstract: Probability density evolution method is proposed for dynamic response analysis of structures with random parameters. In the present paper, a probability density evolution equation (PDEE) is derived according to the principle of preservation of probability. With the state equation expression, the PDEE is further reduced to a one-dimensional partial differential equation. The numerical algorithm is studied through combining the precise time integration method and the finite difference method with TVD schemes. The proposed method can provide the probability density function (PDF) and its evolution, rather than the second-order statistical quantities, of the stochastic responses. Numerical examples, including a SDOF system and an 8-story frame, are investigated. The results demonstrate that the proposed method is of high accuracy and efficiency. Some characteristics of the PDF and its evolution of the stochastic responses are observed. The PDFs evidence heavy variance against time. Usually, they are much irregular and far from well-known regular distribution types. Additionally, the coefficients of variation of the random parameters have significant influence on PDF and second-order statistical quantities of responses of the stochastic structure.

The optimal cordon-based network congestion pricing problem

Abstract: This paper investigates the cordon-based second-best congestion-pricing problems on road networks, including optimal selection of both toll levels and toll locations. A road network is viewed as a directed graph and the cutset concept in graph theory is used to describe the mathematical properties of a toll cordon by examining the incidence matrix of the network. Maximization of social welfare is sought subject to the elastic-demand traffic equilibrium constraint. A mathematical programming model with mixed (integer and continuous) variables is formulated and solved by a combined use of a binary genetic algorithm and a grid search method for simultaneous determination of the toll levels and cordon locations on the networks. The model and algorithm are demonstrated with a numerical example.

Novel luminescent terbium molecular-based hybrids with modified meta-aminobenzoic acid covalently bonded with silica

Abstract: A novel type of sol–gel-derived organic–inorganic molecular-based hybrid material with the two parts covalently linked together via Tb–O and Si–O bonds was synthesized. The organic component was obtained from a derivative of meta-aminobenzoic acid (MAB) which is modified by 3-(triethoxysilyl)-propyl isocyanate, and then the precursor is applied to coordinate to Tb3+ with the carboxyl group and its triethoxysilyl moiety is capable of undergoing polymerization or cross-linking reactions with TEOS (tetraethoxysilane). Accordingly, the final hybrid material is formed by a combination of hydrolysis and polycondensation processes of two ethoxy groups (both MAB-Si and TEOS). Ultraviolet absorption, phosphorescent and fluorescent spectra were used to investigate the photophysical properties of the hybrid material, which reveal that the triplet energy of modified meta-aminobenzoic acid matches with the emissive energy level of Tb3+. In this way, the intramolecular energy transfer process took place within this molecular-based hybrid and a strong green emission of Tb3+ was achieved.

Biodiversity and biodiversity conservation in Yunnan, China

Abstract: Yunnan, an inland province at a low latitude and high elevation, lying between 21degrees09'-29degrees15' N and 97degrees32'-106degrees12' E in southwestern China, has a vast territory with diversified and unique nature resources. There are more than 18 000 high plant species (51.6% of China's total) and 1836 vertebrate species (54.8% of China's total) living in Yunnan on a land area of 39.4 x 10(4) km(2), i.e., only 4.1% of China's total. Among 15000 seed plants found in Yunnan there are 151 rare and endangered plant species (42.6% of China's protected plants). Out of 335 China priority protected wild animals, Yunnan has 243 species, accounting for 72.5% of China's total, 15% of which are species endemic to Yunnan. However, Yunnan's biodiversity is faced with the menace of excessive exploitation of resources and changes in environmental conditions caused by the activities of an expanding human population. This paper discusses the background, the composition, and the structure of Yunnan's biodiversity. Its biodiversity fragility and the threatened situation are also discussed. Suggestions and recommendations on the strategy and actions of Yunnan biodiversity conservation and sustainable development are proposed.

Verification and modeling of three-stage permanent deformation behavior of asphalt mixes

Abstract: In laboratory testing of asphalt mixtures, the relationship between the number of load repetitions and permanent deformation has been found to include three distinct stages, namely the primary, secondary and tertiary stages. Similar permanent deformation behavior has also been observed in the field accelerated pavement testing data. It is argued that the three-stage permanent deformation behavior is a basic material property and to comprehensively model asphalt layer behavior, it is necessary to develop a model that accurately characterizes this behavior. In this paper, each of the well-known models critically reviewed appears that they are limited to characterizing only the primary stage. Therefore, a new three-stage model is proposed to describe all three stages. Moreover, an algorithm is established to determine the model parameters from typical laboratory data. The algorithm can also be used to identify the transition point between stages, such as flow number. The proposed model and algorithm are demonstrated through laboratory test results. The analysis results match the field performance.

Signal timing of intersections using integrated optimization of traffic quality, emissions and fuel consumption: a note

Abstract: In the proposed signal timing model, a performance index function for optimization is defined to reduce vehicle delays, fuel consumption and emissions at intersections. The model optimizes the signal cycle length and green time by considering the constraint of a minimum green time to allow pedestrians to cross. The data used in a case study is from an intersection in Nanjing city. The relationships between the signal cycle length and vehicle delay, fuel consumption, emission, and performance index function are analyzed.

Late Miocene and mid-Pliocene enhancement of the East Asian monsoon as viewed from the land and sea

Abstract: The late Miocene onset of the Indian monsoon and the late Miocene and middle Pliocene enhancement of the East Asian monsoon appear to be the result of coeval uplift episodes in the Himalayan–Tibetan region. A decrease of the abundance ratio of planktonic foraminifera Globigerinoides sacculifer / G. ruber and increase of Neogloboquadrina approximately 8 Myr at ODP site 1146 in the South China Sea indicate lowering of the surface temperature and increased productivity, which are interpreted to have been caused by an intensified influence of the East Asian winter monsoon winds. In the Arabian Sea, monsoon-driven upwelling indicated by the appearance and abundance of planktonic foraminifera G. bulloides and radiolaria increased remarkably at ∼8 Myr. Wind-blown sediment started to accumulate over a wide area of the Chinese Loess Plateau at ∼8 Myr, about the same time as a pronounced pulse of eolian dust to the North Pacific, as revealed at ODP site 885/886, indicating onset of widespread aridity in the Asian interior. At 3.6 Myr, the accumulation of eolian sediment increased by about an order of magnitude, both at proximal settings in China and in the distal North Pacific Ocean. The planktonic foraminifera Neogloboquadrina also underwent a further increase in abundance in the South China Sea at this time. Existing evidence from inland Asia and the surrounding seas suggests a late Miocene onset (or significant intensification) of the East Asian and Indian monsoons, the reason being their link with the uplift of the Himalayas and the Tibetan Plateau. The first increase in mean sediment flux to the Indian Ocean at 11 Myr and strong peak beginning between 9 and 8 Myr indicates the rising of the Himalayas. That rise could have reached sufficient height to produce a rain shadow in Central Asia, causing aridity and providing a source of dust to be transported eastwards into north China and the North Pacific. Further rapid uplift of the entire Tibetan Plateau at 3.6 Myr, as evidenced by the extensive conglomerates of that age on the north flank of the Plateau, resulted in further aridity in the basins of central and eastern Asia, an enhanced East Asian monsoon, and a second, late Pliocene, pulse of terrigenous sedimentation in the Indian Ocean.

Rheology of poly(propylene)/clay nanocomposites

Abstract: The linear and nonlinear shear rheological behaviors of poly(propylene) (PP)/clay (organophilic-montmorillonite) nanocomposites (PP/org-MMT) were investigated by an ARES rheometer. The materials were prepared by melt intercalation with maleic anhydride functionalized PP as a compatibilizer. The storage moduli (G′), loss moduli (G″), and dynamic viscosities of polymer/clay nanocomposites (PPCNs) increase monotonically with org-MMT content. The presence of org-MMT leads to pseudo-solid-like behaviors and slower relaxation behaviors of PPCN melts. For all samples, the dependence of G′ and G″ on ω shows nonterminal behaviors. At lower frequency, the steady shear viscosities of PPCNs increase with org-MMT content. However, the PPCN melts show a greater shear thinning tendency than pure PP melt because of the preferential orientation of the MMT layers. Therefore, PPCNs have higher moduli but better processibility compared with pure PP.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2427–2434,2004

Structure and non-linear optical performance of TeO2–Nb2O5–ZnO glasses

Abstract: The non-linear optical performance and structure of TeO 2 –Nb 2 O 5 –ZnO glasses was investigated as a function of ZnO content. The third-order non-linear optical susceptibility ( χ (3) ) as measured by a Degenerate Four Wave Mixing (DFWM) method, initially increased with increasing ZnO content to about 8.2 × 10 −13 esu for a glass containing 2.5 wt% ZnO, and then decreased to 5.9 × 10 −13 esu as the ZnO content increased to 10 wt%. There was no noticeable change as the ZnO content increased from 10 to 15 wt%. The non-linear optical response time, which caused electron cloud deformation, was from 450 to 500 fs. The structure of these glasses as analyzed by Raman spectroscopy and FT-IR spectra, was affected by the addition of ZnO up to 5 wt%, when, it is believed, the Zn 2+ ions occupied the interstitial positions in the glass network by replacing the Nb 5+ ions. The replaced Nb 5+ ions occupied the network forming positions as the Te 4+ ions. Increasing ZnO > 5 wt% did not have any further effect on the glass structure.

Rough Set Models on Two universes

Abstract: This paper focuses on rough set models on two universes and reveals some new properties. A revised rough set model is proposed which provides a new selection of interval structures for uncertain reasoning using rough set theory and methods.

Reversible data hiding using integer wavelet transform and companding technique

Abstract: This paper presents a novel reversible data-embedding method for digital images using integer wavelet transform and companding technique. This scheme takes advantage of the Laplacian-like distribution of integer wavelet coefficients in high frequency subbands, which facilitates the selection of compression and expansion functions and keeps the distortion small between the marked image and the original one. Experimental results show that this scheme outperforms the state-of-the-art reversible data hiding schemes.