Through silicon via (TSV) is the key technology for 3-D integrated circuits (3-DICs) which could vertically stack homogeneous or heterogeneous dies with the high performance and density. To evaluate ...the electrical characteristics of TSV at the high-frequency transmission, the skin effect and surface roughness effect are necessary to be considered. However, these effects would significantly result in the TSV equivalent resistance under the high operating frequency. Thus, it is important to investigate the carbon nano tubes (CNTs) TSV which has less skin effect intrinsically. In this work, we analyze the advantage of CNTs as TSV compared to the conventional filling materials such as copper (Cu). Furtherly, we also propose the equivalent circuit model of TSV and its multi-layer structure to simulate the electrical behaviors with different TSV pitch, height, diameter, and stacking layers by using ANSYS designer and high-frequency structure simulator (HFSS). Based on the frequency-domain analysis, it can be found that CNTs TSV has the lower frequency-dependent loss than Cu due to the lower equivalent resistance. In a summary, CNTs could be a promising TSV filling material at the high-speed transmission frequency based on our study.
A novel implicit dynamic system is exploited and investigated for online simultaneous linear equations solving. Compared to the classic gradient‐based dynamic system and the recently‐proposed Zhang ...dynamic system, the proposed implicit dynamic system can achieve superior global exponential convergence performance. Theoretical analysis and computer simulation results substantiate the effectiveness and efficiency of the proposed model for the real‐time solution of simultaneous linear equations.
Long non-coding RNAs (lncRNAs) are important regulators of diverse biological processes. Here we report on functional identification and characterization of a novel long intergenic non-coding RNA ...with MyoD-regulated and skeletal muscle-restricted expression that promotes the activation of the myogenic program, and is therefore termed Linc-RAM (Linc-RNA Activator of Myogenesis). Linc-RAM is transcribed from an intergenic region of myogenic cells and its expression is upregulated during myogenesis. Notably, in vivo functional studies show that Linc-RAM knockout mice display impaired muscle regeneration due to the differentiation defect of satellite cells. Mechanistically, Linc-RAM regulates expression of myogenic genes by directly binding MyoD, which in turn promotes the assembly of the MyoD-Baf60c-Brg1 complex on the regulatory elements of target genes. Collectively, our findings reveal the functional role and molecular mechanism of a lineage-specific Linc-RAM as a regulatory lncRNA required for tissues-specific chromatin remodelling and gene expression.
Abstract The success of craniomaxillofacial (CMF) surgery depends not only on the surgical techniques, but also on an accurate surgical plan. The adoption of computer-aided surgical simulation (CASS) ...has created a paradigm shift in surgical planning. However, planning an orthognathic operation using CASS differs fundamentally from planning using traditional methods. With this in mind, the Surgical Planning Laboratory of Houston Methodist Research Institute has developed a CASS protocol designed specifically for orthognathic surgery. The purpose of this article is to present an algorithm using virtual tools for planning a double-jaw orthognathic operation. This paper will serve as an operation manual for surgeons wanting to incorporate CASS into their clinical practice.
Herein we report a novel synthetic entry to the legendary quinuclidine natural products quinine and quinidine. The developed strategy is based on the use of a symmetrical and nonstereogenic precursor ...to access quinine and quinidine through a “local‐desymmetrization” approach, in stark contrast conceptually to the preparation of stereodefined disubstituted piperidines (or their acyclic precursors) as featured in all past syntheses. The developed strategy also provided quinine and quinidine derivatives that could not be readily obtained through previous total syntheses or by modification of the naturally occurring substances.
Seeing old friends in a new light: A divergent synthesis of quinine and quinidine (see structures) was designed on the basis of a symmetrical and nonstereogenic intermediate, conceptually different from the stereodefined piperidine precursors used in past syntheses. Complementary late‐stage local‐desymmetrization reactions were developed to access the two targets. The strategy also enabled the synthesis of novel quinine and quinidine derivatives.
To understand carbon cycling in marginal seas better, particulate organic carbon (POC) concentrations, POC fluxes and primary production (PP) were measured in the East China Sea (ECS) in summer 2007. ...Higher concentrations of POC were observed in the inner shelf, and lower POC values were found in the outer shelf. Similar to POC concentrations, elevated uncorrected POC fluxes (720–7300 mg C m−2 d−1) were found in the inner shelf, and lower POC fluxes (80–150 mg C m−2 d−1) were in the outer shelf, respectively. PP values (~ 340–3380 mg C m−2 d−1) had analogous distribution patterns to POC fluxes, while some of PP values were significantly lower than POC fluxes, suggesting that contributions of resuspended particles to POC fluxes need to be appropriately corrected. A vertical mixing model was used to correct effects of bottom sediment resuspension, and the lowest and highest corrected POC fluxes were in the outer shelf (58 ± 33 mg C m−2 d−1) and the inner shelf (785 ± 438 mg C m−2 d−1), respectively. The corrected POC fluxes (486 to 785 mg C m−2 d−1) in the inner shelf could be the minimum value because we could not exactly distinguish the effect of POC flux from Changjiang influence with turbid waters. The results suggest that 27–93% of the POC flux in the ECS might be from the contribution of resuspension of bottom sediments rather than from the actual biogenic carbon sinking flux. While the vertical mixing model is not a perfect model to solve sediment resuspension because it ignores biological degradation of sinking particles, Changjiang plume (or terrestrial) inputs and lateral transport, it makes significant progress in both correcting the resuspension problem and in assessing a reasonable quantitative estimate of POC flux in a marginal sea.
With the usage of gas ferrocene Fe(C 5 H 5 ) 2 as a reactant, which is different from the traditional thin Fe film, to grow the high-quality carbon nanotubes (CNTs) in the high aspect ratio (AR) ...trench structure, it has many advantages to be the through-silicon vias (TSVs) material for the three-dimensional (3-D) stacking technology. In this work, we successfully demonstrate the full process flow, including CNT growing, chemical-mechanical planarization (CMP), and wafer temporary bonding for CNTs as TSVs in the 3-D stacking connection. The flexibility for this demonstrated process flow makes the integration of real high dense devices and CNTs as TSVs for the 3-D connection more easily.
The preparation of high-purity and -quality gallium nitride nanowires is accomplished by a catalytic growth using gallium and ammonium. A series of catalysts and different reaction parameters were ...applied to systematically optimize and control the vapor−liquid−solid (VLS) growth of the nanowires. The resulting nanowires show predominantly wurtzite phase; they were up to several micrometers in length, typically with diameters of 10−50 nm. A minimum nanowire diameter of 6 nm has been achieved. Temperature dependence of photoluminescence spectra of the nanowires revealed that the emission mainly comes from wurtzite GaN with little contribution from the cubic phase. Moreover, the thermal quenching of photoluminescence was much reduced in the GaN nanowires. The Raman spectra showed five first-order phonon modes. The frequencies of these peaks were close to those of the bulk GaN, but the modes were significantly broadened, which is indicative of the phonon confinement effects associated with the nanoscale dimensions of the system. Additional Raman modes, not observed in the bulk GaN, were found in the nanowires. The field emission study showing notable emission current with low turn-on field suggests potential of the GaN nanowires in field emission applications. This work opens a wide route toward detailed studies of the fundamental properties and potential applications of semiconductor nanowires.
Vegetation indices are valuable in many fields of geosciences. Conventional, visible-near infrared, indices are often limited by the effects of atmosphere, background soil conditions, and saturation ...at high levels of vegetation. In this study, we will establish the theoretical basis for our new passive microwave vegetation indices (MVIs) based on data from the Advanced Microwave Scanning Radiometer (AMSR-E) on the Aqua satellite. Through the analysis of numerical simulations by surface emission model, the Advanced Integral Equation Model (AIEM), we found that bare soil surface emissivities at different frequencies can be characterized by a linear function with parameters that are dependent on the pair of frequencies used. This makes it possible to minimize the surface emission signal and maximize the vegetation signal when using multi-frequency radiometer measurements. Using a radiative transfer model (
ω–
τ model), a linear relationship between the brightness temperatures observed at two adjacent radiometer frequencies can be derived. The intercept and slope of this linear function depend only on vegetation properties and can be used as vegetation indices. These can be derived from the dual-frequency and dual-polarization satellite measurements under assumption that there is no significant impact of the polarization dependence on the vegetation signals. To demonstrate the potential of the new microwave vegetation indices, we compared them with the Normalized Difference of Vegetation Index (NDVI) derived using MODIS the optical sensor at continental and global scales. The major purpose of this paper is to describe the concept and techniques involved in these newly developed MVIs and explore the general relationships between these MVIs and NDVI. In this first investigation, the information content of NDVI and MVIs, both are qualitative indices, was compared by examining its response in global pattern and to seasonal vegetation phenology. The results indicate that the MVIs can provide significant new information since the microwave measurements are sensitive not only to the leafy part of vegetation properties but also to the properties of the overall vegetation canopy when the microwave sensor can “see” through it. In combination with conventional optical sensor derived vegetation indices, they provide a possible complementary dataset for monitoring global short vegetation and seasonal phenology from space.
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