Vacuum filtration is a highly effective and easy scale-up approach and has been widely used to fabricate graphene monoliths, such as graphene paper and graphene frameworks for various applications. ...In general, the microstructure of filtrated monoliths exhibits layer-by-layer stacking of graphene sheets due to the directional flow-induced assembly process. In this work, we found that the horizontally oriented structure of filtrated graphene frameworks can be modulated to an approximately isotropic arrangement by lowering the lateral size of graphene sheets. This size-dependent microstructure transition from anisotropic to isotropic was further confirmed by measuring the in- and through-plane thermal conductivity of the graphene/epoxy composites with different arrangements of graphene frameworks as a filler. Optimally, we obtained an epoxy composite embedded with a quasi-isotropic graphene framework (QIGF) by a simple two-step process: vacuum filtration of small graphene sheets to obtain the framework followed by the infiltration of epoxy resin. Based on the interconnected graphene sheets with an approximately isotropic arrangement, QIGF provides heat channels of graphene-graphene along both the in- and through-plane directions within epoxy. With a low graphene loading of 5.5 wt%, QIGF/epoxy (QIGF/EP) presents in- and through-plane thermal conductivities of 10.0 and 5.4 W mK
−1
, respectively, which are equivalent to ∼55 and 29 times higher than those of neat epoxy. As compared to the current graphene/epoxy composites prepared by various methods, our QIGF/EP has the highest thermal conductivity value with this level of filler loading. Our findings provide an insight for the development of polymer composites for thermal management applications in industry.
Graphene frameworks composed of quasi-isotropic and interconnected graphene were constructed
via
the filtration of graphene sheets with a small lateral size, endowing an epoxy composite (5.5 wt% graphene addition) with in- and through-plane thermal conductivities ∼55 and 29 times higher than those of neat epoxy, respectively.
Organic phase-change materials possess immense application potential, but their low thermal conductivity (≤ 0.5 W m-1 K-1) severely limits the thermal energy charge/discharge rate, impeding their ...practical implementation in the field of advanced energy. While incorporating thermally conductive fillers into the phase-change matrix can address this issue, achieving a thermal conductivity exceeding 10 W m-1 K-1 at filler content below 30 vol% remains challenging, attributed to the absence of a well-designed filler interface and structure. Herein, a strategy for developing planar graphene clusters and subsequently integrating them with phase-change microcapsules to fabricate composites using compression molding was demonstrated. The proposed graphene clusters are formed by closely aligned and overlapping graphene sheets that bond together through van der Waals forces, resulting in a significant decrease in junction thermal resistance within the composites. Combining this interface design with compression-induced construction of a highly oriented structure, the composites achieved a remarkable thermal conductivity of 103 W m-1 K-1 with ≈ 29 vol% filler addition, enhancing the thermal energy charge/discharge rate by over two orders of magnitude. Furthermore, we demonstrated that the composites possess the essential enthalpy values, competent strength, and ease of shaping, making them applicable across various domains of thermal energy management.
This paper is based on our previous study of automatic liver segmentation, and proposes an automatic approach for the detection of near-spherical liver tumors. Firstly, an improved variable quoit ...filter model is presented, which utilizes the characteristics of the ring-shaped filter to detect the rotationally symmetric structure. Secondly, in order to improve the detection performance of quoit filter, the sensitivity of multi-size tumor is enhanced by a specially designed grey-scale weight-based distance transformation function. Finally, support vector machine classification algorithm is adopted to reduce the false positive of classification. Experiment on 20 sets of abdominal CT images shows that the modified filter can achieve a better performance than the conventional filter, which indicates a promising prospect for spherical liver tumors detection.
Carbon-protected magnetic nanoparticles exhibit long-term stability in acid or alkaline medium, good biocompatibility, and high saturation magnetization. As a result, they hold great promise for ...magnetic resonance imaging, photothermal therapy, etc. However, since pyrolysis, which is often required to convert the carbon precursors to carbon, typically leads to coalescence of the nanoparticles, the obtained carbon-protected magnetic nanoparticles are usually sintered as a non-dispersible aggregation. We have successfully synthesized discrete, dispersible, and uniform carbon-protected magnetic nanoparticles via a precise surface/interface nano-engineering approach. Remarkably, the nanoparticles possess excellent water-dispersibility, biocompatibility, a high T2 relaxivity coefficient （384 mM^-1·s^-1）, and a high photothermal heating effect. Furthermore, they can be used as multifunctional core components suited for future extended investigation in early diagnosis, detection and therapy, catalysis, separation, and magnetism.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The type of the workload is one of the key factors on database management system (DBMS) tuning. Different types of workload (OLTP, online transaction processing and OLAP, online analytical ...processing) mean different resource allocation strategies. In this paper, we present an approach to automatically identify a DBMS workload as either OLTP or OLAP. We use C5.0 algorithm to construct a set of classifiers based on the characteristics that differentiate OLTP and OLAP and then use the classifier to identify the workload type. The experiments show that the classifiers can be able to accurately identify the OLTP and OLAP workloads.
Finding the large item set fast is the crucial step in the association rule algorithm. In this paper we apply granular computing and quotient space to frequent item set discovering , by partition the ...information system to information granule and mapping granule object sets, the algorithm reduced the number of database scanning and reduced object sets required when computing support of candidate item, in this way we improved the efficient of running. For the dataset of small support with high complexity, it is more applicable. The experiment results show: the proposed method is effective.
A 9 1/2-year pharmaco-cavernosometry/pharmaco-cavernosography and pharmaco-arteriography study was performed in 131 men with persistent changes in erectile function following blunt pelvic or perineal ...trauma. The goal was to determine the incidence of hemodynamic impairment, and to characterize the location and pattern of abnormal venous drainage. Corporeal veno-occlusive dysfunction was identified in 62 percent of the cases and cavernous artery insufficiency in 70 percent.
Pharmaco-cavernosography revealed abnormal venous drainage confined to the proximal corpora in 91 percent of the cases. Patients with pelvic trauma had significantly more abnormal sites of venous drainage (3 or more sites in 61 percent) and more severe degrees to which venous structures filled with contrast medium (23 percent had 3+ degree of luminal filling) than did patients with perineal trauma (61 percent had 1 or 2 sites of venous drainage and 92 percent had 1+ or 2+ degree of luminal filling). Pharmaco-arteriography revealed site specific arterial occlusive lesions consistent with the site of impact. Traumatic vasculogenic impotence is hypothesized as being the result of direct impact injury to the fixed proximal corpora and its arterial inflow bed. The exerted perineal impact force is estimated to range from 50 to 500 pounds, depending on the weight of the individual, height of the fall, speed at contact and surface hardness. Traumatic veno-occlusive dysfunction is theorized to be the consequence of focal intracavernous wound repair and permanent focal alterations in erectile tissue compliance. Traumatic vasculogenic impotence afflicts an estimated 600,000 American men of whom 250,000 have sports-related injuries. Future consideration should be given to the development of appropriate protective perineal equipment.
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