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A green, low-cost and highly efficient surface-enhanced Raman scattering (SERS) substrate was achieved by a chemical deposition of silver nanoparticles on a cicada wing, which has the largescale nanosized protrusions on its surface. Employing the already-formed Ag/cicada wing as substrate for SERS detection, the detection limit for rhodamine 6G could reach 10-7M, the Raman enhancement factor of the substrate was as large as 106 and the relative standard deviation remains lower than 7%. The three-dimensional finite-difference time-domain simulation results showed that two types of inter-Ag-nanoparticle nanogaps in the formed geometry created a huge number of SERS "hot spots" where the electromagnetic field is substantially amplified and contributes to the higher SERS sensitivity. Meanwhile, the water contact angle of the SERS substrate is roughly 150°, which indicates the super-hydrophobic surface of the substrate. This feature may be conducive to the gathering of target molecules during the SERS detection, which in turn further improves the detection limit of target molecules. In order to improve the application of the substrate, thiram was used as the probe molecule, and the detection limit also reached 10-7 M. Meanwhile, the calibration of the Raman peak intensities of Rhodamine 6G and thiram allowed their quantitative detection. Therefore, the green and low-cost SERS substrates could be used for fast and quantitative detection of trace organic molecules. Our findings may contribute to the development of the green and low-cost SERS substrates and will allow the fast and quantitative detection of trace organic molecules. [ABSTRACT FROM AUTHOR]

A large scale heterostructure array of ZnO nanowires/silicon nanoporous pillar array (Si-NPA) was prepared by a self-catalytic thermal evaporation and vapor-phase transport method, and an ultrahigh field emission current density of 1.55 mA cm-2 was obtained under an operating electric field of 4.0 V μm-1, with a low turn-on field of 1.65 V μm-1. The enhancement factor calculated according to the Fowler-Nordheim theory was ∼3141. The excellent field emission performance was attributed to the unique structure of ZnO/Si-NPA, especially the formation of ZnO nanowires on regular Si pillar array. Our work indicated that ZnO/Si-NPA might be an ideal candidate cathode of potential applications in flat panel displays and high brightness electron sources. [ABSTRACT FROM AUTHOR]

Aiming at the serious deformation problem of the roadway supported along gob-side by stowing with high-water-content packing on the engineering background of No. 1200 working face, the technologies of supporting beside the roadway by stowing with high-water-content packing and relieving pressure by roof-cutting along gob-side entry are applied in different sections respectively. Based on the engineering geological conditions of the working face, the roof-cutting parameter is calculated and some technologies have been put into use in the project: high constant resistance and large deformation (CRLD) cable supporting technology; bilateral cumulative tensile explosion technology; gangue blocking supporting technology. Arm-shortening beam resulting from roof-cutting cuts down the cantilever beam length of roadway roof. CRLD cable supporting can effectively improve the mechanical properties of roof strata. The roof collapses smoothly within the height of cutting seam along the gob-side entry, filling the gob with gangue quickly. The point where the gob roof touches the collapsed gangue moves toward the remained roadway side and the subsiding and rotary deformation problem of gangue-formed wall gets under control and the subsiding level is reduced. Compared with the original backfilling body, the collapsed gangue weakens the level of stress concentration. Meanwhile, the subsiding of minor roofs and the roof strengthening can dramatically reduce the bottom heave. Engineering practice has proved that in such mining geological conditions, the method of releasing pressure by roof-cutting along gob-side entry can effectively decrease the deformation of the retained roadways, greatly reduce the workload, enhance productivity and guarantee the remarkable benefit of retaining roadway economy. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to present normative data of tympanometric measurements of wideband acoustic immittance and to characterize wideband tympanograms. Method: Data were collected in 84 young adults with strictly defined normal hearing and middle ear status. Energy absorbance (EA) was measured using clicks for 1/12--octave frequencies (0.236 to 8 kHz), with the ear canal air pressure systematically varied (+200 to -300 daPa). In 40 ears, 7 consecutive trials and a trial of clinical 226-Hz acoustic admittance (Ya) tympanometry followed. A cavity test was also conducted. Results: From the wideband EA tympanogram, several EA spectrums and EA tympanograms were derived. Descriptive statistics were performed, and population parameters were estimated. The immediate test--retest reliability was excellent. Effects of ear canal air pressure on EA were examined comprehensively. Differences in EA between tympanometric and ambient-pressure measurements were significant. Single-frequency EA tympanograms exemplified for half-octave frequencies were contrasted. The bandpass EA tympanogram, 0.236- and 1-kHz EA and Ya tympanograms, and 226-Hz Ya tympanogram were compared in 9 variables. Conclusions: This study established a database of wideband tympanograms in healthy adults. The data analyses will promote our understanding of the middle ear transfer function. These data will serve as a reference for further studies in clinical populations. [ABSTRACT FROM AUTHOR]

Suspended sediment concentration (SSC) is one of the most critical parameters in ocean ecological environment evaluation and it can be determined using ocean color remote sensing (RS). The purpose of this study is to develop a model that provides a reliable and sensitive evaluation of SSC retrieval using RS data. Data were acquired for and gathered from the Gulf of Bohai where SSC levels are relatively low with an average value below 30 mg·L-1. The study indicates that the most sensitive band to SSC levels in the study area is the NIR band of Landsat5 TM images. A quadratic polynomial semi-analytical model appears to be the best retrieval model based on the relationship between the inherent optical properties (IOPs) and apparent optical properties (AOPs) of water as described by the quasi-analytical algorithm (QAA). The model has a higher precision and effectiveness for SSC retrieval than data-driven statistical models, especially when SSC level is relatively high. The average relative error and the root mean square error (RMSE) are 12.32% and 4.53 mg·L-1, respectively, while the correlation coefficient between observed and estimated SSC by the model is 0.95. Using the proposed retrieval model and TM data, SSC levels of the entire study region in the Gulf of Bohai were estimated. These estimates can serve as the baseline for efficient monitoring of the ocean environment in the future. [ABSTRACT FROM AUTHOR]

A hybrid film of carbon nanotubes (CNTs) and silver nanowires (AgNWs) that could be regarded as a parallel circuit of CNTs and AgNWs was developed, which exhibited a low sheet resistance of 23 Ω/sq and transmittance at 550 nm of 93%. The relatively high, intertube contact resistance of CNTs was reduced by the metallic AgNWs, which acted as bridges to aid carrier transport between CNTs. A hybrid film of CNTs and AgNWs was used as a transparent conductive layer in an AlGaInP light-emitting diode (LED). Including the hybrid film in the LED increased the optical output power by about 1.6 times and decreased the red shift of emission wavelength from 13.11 to 9.7. [ABSTRACT FROM AUTHOR]

Purpose: Wideband acoustic immittance (WAI) is a new technique for assessing middle ear transfer function. It includes energy absorbance (EA) measures and can be acquired with the ear canal pressure varied, known as wideband tympanometry (WBTymp). The authors of this study aimed to investigate effects of consecutive WBTymp testing on EA. Method: Data were collected in 29 young adults with normal hearing and middle ear status. Before and after 8 successive WBTymp runs, EA was also measured at ambient pressure. Subsequently, two 226-Hz tympanometry tests were performed. Results: EA systematically changed over the WBTymp trials in a frequency-specific manner: increase for low frequencies (below 1.5 kHz) and decrease for high frequencies (around 2 kHz and 5 to 6 kHz). The changes, although small, were significant. Much larger EA changes were measured at ambient pressure. The test–retest difference of 226-Hz tympanogram measures was much smaller than previously reported. Conclusion: Consecutive tympanometry testing alters EA measures of the middle ear. This phenomenon could be mainly attributed to change in stiffness at the eardrum, called tympanometric preconditioning. This also has effects on baseline WBTymp outcomes. This effect should be taken into account as a procedural variable in both research and clinical applications of WAI measurements. [ABSTRACT FROM AUTHOR]

Purpose: Wideband acoustic immittance (WAI) is a new technique for assessing middle ear transfer function. It includes energy absorbance (EA) measures and can be acquired with the ear canal pressure varied, known as wideband tympanometry (WBTymp). The authors of this study aimed to investigate effects of consecutive WBTymp testing on EA. Method: Data were collected in 29 young adults with normal hearing and middle ear status. Before and after 8 successive WBTymp runs, EA was also measured at ambient pressure. Subsequently, two 226-Hz tympanometry tests were performed. Results: EA systematically changed over the WBTymp trials in a frequency-specific manner: increase for low frequencies (below 1.5 kHz) and decrease for high frequencies (around 2 kHz and 5 to 6 kHz). The changes, although small, were significant. Much larger EA changes were measured at ambient pressure. The test–retest difference of 226-Hz tympanogram measures was much smaller than previously reported. Conclusion: Consecutive tympanometry testing alters EA measures of the middle ear. This phenomenon could be mainly attributed to change in stiffness at the eardrum, called tympanometric preconditioning. This also has effects on baseline WBTymp outcomes. This effect should be taken into account as a procedural variable in both research and clinical applications of WAI measurements. [ABSTRACT FROM AUTHOR]

Ag nanoparticles (NPs) coated with silica nanolayers were decorated onto a large-scale and uniform silicon nanowire array (SiNWA) by simple chemical etching and metal reduction processes. The three-dimensional Ag/SiNWAs thus formed are employed as a substrate for surface-enhanced Raman scattering (SERS), and a detection limit for rhodamine 6G as low as 10-16 M and a Raman enhancement factor as large as 1014 were obtained. Simulation results show that two kinds of inter-Ag-NP nanogaps in three-dimensional geometry create a huge number of SERS 'hot spots' where electromagnetic fields are substantially amplified, contributing to the higher SERS sensitivity and lower detection limit. The excellent SERS stability of Ag/SiNWAs is attributed to the presence of the SiO2 nanolayer around Ag NPs that prevented the Ag NP surface from being oxidized. The calibration of the Raman peak intensities of rhodamine 6G and thiram allowed their quantitative detection. Our finding is a significant advance in developing SERS substrates for the fast and quantitative detection of trace organic molecules. [ABSTRACT FROM AUTHOR]

Decomposition of toluene as a typical aromatic volatile organic compound was experimentally investigated in a rotating gliding arc discharge nonthermal plasma reactor. The experiments were conducted at a gas flow rate of 5.4-10.8 m3h-1. Important parameters, including applied voltage, gas flow rate, initial concentration, and water vapor concentration, were investigated. The results showed that a higher applied voltage results in higher toluene removal and higher power deposited into a discharge system; the decomposition achieved was highly dependent on the total gas flow rate. Under the fixed specific energy density (SED), both toluene removal efficiency and energy efficiency decrease with the increase in gas flow rate. The removal efficiency of toluene decreased with an increase in the initial concentration, whereas the absolute removal amount and energy efficiency increased. For example, the removal efficiency decreased from 77% to 56% with the initial toluene concentration ranging from 200 to 2000 m g-3 as the SED was 266 J L-1; the toluene removal efficiency evidently increased as the water vapor concentration increased from 0.5945 to 1708.3435 mg m-3. A dynamics model was developed to describe the relation of the removal efficiency with SED and initial concentration. [ABSTRACT FROM PUBLISHER]

Pavement crack detection plays an important role in the pavement maintaining and management. Recently, the laser scanning technique for pavement crack detection becomes more and more popular due to its ability of discriminating dark areas, which are not caused by pavement distress such as tire marks, oil spills, and shadows. However, this technique still bears some errors for pavement crack recognition errors, thus in the present work, the factors contributed to these errors in laser scanning system are first analyzed, and then a decision model for the laser scanning pavement crack detection system based on the hypothesis test is proposed. Experimental analyses and results show that this model not only allows us to build the relationship between the contribution factors and crack detection accuracy and to provide the criteria to compare the detection accuracy for the different roads, but also can be used to judge whether the crack exists with a reasonable number of deformed light stripes. Therefore, the proposed decision model can provide guidance on the pavement crack detection and has a practical value. [ABSTRACT FROM AUTHOR]

biodegradable tumor targeting nano-probe based on poly( ɛ-caprolactone)- b-poly(ethylene glycol) block copolymer (PCL- b-PEG) micelle functionalized with a magnetic resonance imaging (MRI) contrast agent diethylenetriaminepentaacetic acid-gadolinium (DTPA-Gd) on the shell and a near-infrared (NIR) dye in the core for magnetic resonance and optical dual-modality imaging was prepared. The longitudinal relaxivity ( r) of the PCL- b-PEGDTPA-Gd micelle was 13.4 (mmol/L)s, three folds of that of DTPA-Gd, and higher than that of many polymeric contrast agents with similar structures. The in vivo optical imaging of a nude mouse bearing xenografted breast tumor showed that the dual-modality micelle preferentially accumulated in the tumor via the folic acid-mediated active targeting and the passive accumulation by the enhanced permeability and retention (EPR) effect. The results indicated that the dualmodality micelle is a promising nano-probe for cancer detection and diagnosis. [ABSTRACT FROM AUTHOR]

Hierarchical ZnO/Si nanoheterostructure was prepared by growing oriented ZnO nanowire bundles onto the top of nanoporous silicon pillar array (NSPA) via a self-catalytic thermal evaporation and vapor-phase transport method. Samples were carefully characterized using field emission scanning electron microscopy, x-ray diffraction, and luminescence spectroscopy. One ultraviolet, one blue-green, and two red emission bands were observed in ZnO/NSPA, and the emission mechanism is discussed by developing a model-based energy band diagram. The origins of the ultraviolet and blue-green photoluminescence (PL) bands were attributed to the emission from the band edge transition and surface states of oxygen vacancies of ZnO, while two red PL bands originated from NSPA and could be well explained by the quantum confinement-luminescence center model. The realization of such all solid and wide wavelength nanodevice might be both meaningful for developing new concept lighting devices and potentially extended to fabricate hierarchical Si-based nanoheterostructures in fabricating other optoelectronic nanodevices. [ABSTRACT FROM AUTHOR]

The results of a theoretical study of the reaction mechanism for the neutral hydration of ketene, HC=C=O + ( n + 1) HO → CHCOOH + nHO ( n = 0-4), in solution are presented. All structures were optimized and characterized at the MP2(fc)/6-31 + G* level of theory, and then re-optimized by MP2(fc)/6-311 ++G**, and the effect of the bulk solvent is taken into account according to the conductor-like polarized continuum model (CPCM) using the gas MP2(fc)/6-311 ++G** geometries. Energies were refined for five-water hydration at higher level of theory, QCISD(T)(fc)/6-311 ++G**//MP2(fc)/6-311 ++G**. In the combined supermolecular/continuum model, one water molecule directly attacks the central C-atom, and the other four explicit water molecules are divided into two groups, one acting as catalyst(s) by participating in the proton transfer to reduce the tension of proton transfer ring, and the other being placed near the non-reactive oxygen or carbon atom in order to catalyze the hydration by engaging in hydrogen-bonding to the substrate (the so-called cooperative effect). Between the two possible nucleophilic addition reactions of water molecule, across the C=O bond or the C=C bond, the former one is preferred. Our calculations suggest that the favorable hydrolysis mechanism of ketene involves a sort of eight-membered ring transition structure formed by a three-water proton transfer loop, and a cooperative dimeric water near the non-reactive carbon-atom. The best-estimated in the present paper for the rate-determining barrier in solution, $$ \Updelta G_{\text{sol}}^{ \ne } $$ (298 K), is about 58 kJ/mol, reasonably close to the available experimental result. [ABSTRACT FROM AUTHOR]

The water-catalyzed hydrolysis reaction of carbon disulfide (CS2) has been investigated at the levels of HF and MP2 with the basis set of 6-311++G(d,p) using the combined supramolecular/continuum models, in which up to six water molecules are involved in the hydrolysis and the effect of water bulk solvent is taken into account according to the polarizable continuum model (PCM). The activation Gibbs free energies in water solution, ΔGsol≠ (298 K), for the rate-determining steps of one up to six water hydrolyses are 247.9, 184.2, 152.3, 141.8, 134.4, and 118.9 kJ/mol, respectively. The most favorable hydrolysis path of CS2 involves a sort of eight-membered ring transition structure formed by six water molecules, among which three water molecules are not involved in the proton transfer, two near to the nonreactive sulfur atom, and one below the parent carbon disulfide. This suggests that the hydrolysis of CS2 can be mediated with the water molecule(s) and be significantly facilitated by the cooperative effects of the water molecule(s) in the nonreactive region. The catalytic effects of water molecule(s) due to the alleviation of ring strain in the proton transfer process may result from the synergistic effects of rehybridization and charge reorganization from the prereaction complex to the rate-determining transition state structure induced by water molecule(s). PCM solvation models could significantly lower the rate-determining activation Gibbs free energies by 20–38 kJ/mol when two up to six explicit water molecules involved in the neutral hydrolysis of CS2. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009 [ABSTRACT FROM AUTHOR]

Alteration of the distortion product otoacoustic emission (DPOAE) level by a contralateral sound, which is known as DPOAE contralateral suppression, has been attributed to the feedback mechanism of the medial olivocochlear efferents. However, the limited dynamic range and large intra- and intersubject variabilities in the outcome of the measurement restrict its application in assessing the efferent function. In this study, the 2f1-f2 DPgram was measured with a high frequency resolution in six human ears, which exhibits a fine structure with the quasiperiodic appearance of peaks and dips. In the presence of contralateral noise, the DPOAE level increased, decreased, or remained unchanged depending on the frequency. At the peaks, DPOAEs were mostly suppressed with a larger change, while those at the dips had greater variance, with increased occurrence of enhancement or no change. The difference between the peak and dip frequencies in the DPOAE-level change was significant. A switch from suppression to enhancement of the DPOAE level or vice versa with a small change in frequency was noted. These results imply that the DPOAE fine structure is a main source of the variability in DPOAE contralateral suppression measurement. The study suggests that the DPOAE contralateral suppression test would be improved if it is conducted for frequencies at major peaks of the DPOAE fine structure. [ABSTRACT FROM AUTHOR]

This paper addresses the multi-period two-echelon integrated competitive/uncompetitive facility location problem in a distribution system design that involves locating regional distribution centers (RDCs) and stores, and determining the best strategy for distributing the commodities from a central distribution center (CDC) to RDCs and from RDCs to stores. The goal is to determine the optimal numbers, locations and capacities of RDCs and stores so as to maximize the total profit of the distribution system. Unlike most of past research, our study allows for dynamic planning horizon, distribution of commodities, configuration of two-echelon facilities, availability of capital for investment, external market competition, customer choice behavior and storage limitation. This problem is formulated as a bi-level programming model and a mutually consistent programming mode, respectively. Since such a distribution system design problem belongs to a class of NP-hard problem, a genetic algorithm-based heuristic (GA) is presented and compared with random search solution and mutually consistent solution (MC) using numerical example. The computational results show that the GA approach is efficient and the values of the performance index were significantly improved relative to the MC. [ABSTRACT FROM AUTHOR]

Raf-1 protein kinase has been identified as an integral component of the Ras/Raf/MEK/ERK signalling pathway in mammals. Activation of Raf-1 is achieved by Ras.GTP binding and other events at the plasma membrane including tyrosine phosphorylation at residues 340/341. We have used gene targeting to generate a `knockout' of the raf-1 gene in mice as welt as a rafFF mutant version of endogenous Raf-1 with Y340FY341F mutations. Raf-1-/- mice die in embryogenesis and show vascular defects in the yolk sac and placenta as welt as increased apoptosis of embryonic tissues. Cell proliferation is not affected. Raf-1 from cells derived from raf-1FF/FF mice has no detectable activity towards MEK in vitro, and yet raf-1FF/FF mice survive to adulthood, are fertile and have an apparently normal phenotype. In cells derived from both the raf-1-/- and raf-1FF/FF mice, ERIC activation is normal. These results strongly argue that MEK kinase activity of Raf-1 is not essential for normal mouse development and that Raf-1 plays a key role in preventing apoptosis. [ABSTRACT FROM AUTHOR]

During apoptosis, release of cytochrome c initiates dATP-dependent oligomerization of Apaf-1 and formation of the apoptosome. In a cell-free system, we have addressed the order in which apical and effector caspases, caspases-9 and -3, respectively, are recruited to, activated and retained within the apoptosome. We propose a multi-step process, whereby catalytically active processed or unprocessed caspase-9 initially binds the Apaf-1 apoptosome in cytochrome c/dATP-activated lysates and consequently recruits caspase-via an interaction between the active site cysteine (C287) in caspase-9 and a critical aspartate (D175) caspase-3. We demonstrate that XIAP, an inhibitorof- apoptosis protein, is normally present in high molecular weight complexes in unactivated cell lysates, but directly interacts with the apoptosome cytochrome c/dATP-activated lysates. XIAP associates with oligomerized Apaf-1 and/or processed caspase- and influences the activation of caspase-3, but also binds activated caspase-3 produced within the apoptosome and sequesters it within the complex. Thus, XIAP may regulate cell death by inhibiting the activation of caspase-3 within the apoptosome and by preventing release of active caspase-3 from the complex. [ABSTRACT FROM AUTHOR]