386 research outputs found

    Inorganic hierarchical nanostructures induced by concentration difference and gradient

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    A very simple strategy for preparing hierarchical inorganic nanostructures under ambient aqueous conditions is presented. The hierarchical inorganic nanomaterials were obtained by simply adding a highly concentrated solution of one reactant to a solution of another reactant with low concentration. No surface-capping molecules or structure-directing templates were needed. The preparation of hierarchical single crystalline PbMoO(4) was used as an example in order to study the effects of varying the reaction conditions and the mechanism of the process. It was found that the large concentration difference (typically in excess of 200-fold) and the concentration gradient of the reactants both play key roles in controlling the diffusion process and the morphology of the resulting nanostructures. This kinetically controlled strategy is facile and is easily adapted to prepare a variety of inorganic materials.Chemistry, PhysicalNanoscience & NanotechnologyMaterials Science, MultidisciplinaryPhysics, AppliedSCI(E)0ARTICLE3213-220

    Service differentiation in OFDM-Based IEEE 802.16 networks

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    IEEE 802.16 network is widely viewed as a strong candidate solution for broadband wireless access systems. Various flexible mechanisms related to QoS provisioning have been specified for uplink traffic at the medium access control (MAC) layer in the standards. Among the mechanisms, bandwidth request scheme can be used to indicate and request bandwidth demands to the base station for different services. Due to the diverse QoS requirements of the applications, service differentiation (SD) is desirable for the bandwidth request scheme. In this paper, we propose several SD approaches. The approaches are based on the contention-based bandwidth request scheme and achieved by the means of assigning different channel access parameters and/or bandwidth allocation priorities to different services. Additionally, we propose effective analytical model to study the impacts of the SD approaches, which can be used for the configuration and optimization of the SD services. It is observed from simulations that the analytical model has high accuracy. Service can be efficiently differentiated with initial backoff window in terms of throughput and channel access delay. Moreover, the service differentiation can be improved if combined with the bandwidth allocation priority approach without adverse impacts on the overall system throughput

    Comparison between anterolateral thigh perforator free flaps and pectoralis major pedicled flap for reconstruction in oral cancer patients-A quality of life analysis

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    The aim of this study was to compare the differences between anterolateral thigh perforator free flaps (ALTFF) and pectoralis major myocutaneous flap (PMMF) for reconstruction in oral cancer patients. Method and Patients: who received free flap or PMMF reconstruction after ablation surgeries were eligible for the current study. The patients' demographic data, medical history, and quality of life scores(Medical Outcomes Study-Short Form-36 (MOS SF-36) and the University of Washington Quality of Life (UW-QOL) questionnaires were collected. Results: 81 of 118 questionnaires were returned (68.64%). There was signi.cant differences between two groups in the gender (P<0.005). Patients reconstructed with ALTFF had better appearance domains and better shoulders domains, in addition to better role emotion domains. Conclusions: Using either PMMF or ALTFF for reconstruction of oral defects after cancer resection signi.cantly in.uences a patient's quality of life. Data from this study provide useful information for physicians and patients during their discussion of reconstruction modalities for oral cancers

    Preparation of Low Rolling Resistance Modified Asphalt and Analysis of Its Rolling Resistance and Viscoelasticity

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    Tire tread of running vehicles generates rolling resistance with the pavement, thereby influencing energy consumption. Thus, developing low rolling resistance pavement can improve the service function of tires. Common matrix asphalt and high module binder modifier (HMB-W) was used to obtain low rolling resistance of asphalt and effectively reduce energy consumption. Its low rolling resistance performance was analyzed via internal heat-generating test, rolling resistance test, and dynamic shear rheological test. Then, a rolling resistance model was constructed to evaluate its thermal losses. Test results show that compared with styrene-butadiene-styrene (SBS) modified asphalt and its mastic, the heat generation rates of HMB-W modified asphalt and its mastic are reduced by 14.4% and 15.5%, respectively. Thus, energy loss can be effectively reduced. The generated heat quantity and power loss were reduced by 3.7% and 5%, respectively, compared with the SBS modified asphalt. In addition, the low rolling resistance is evident. HMB-W asphalt has low-temperature sensitivity and superior high-temperature stability. Under the same stress level, the complex shear module G* of HMB-W asphalt is evidently higher than that of SBS modified asphalt. Under the same temperature condition, the energy stored is high when HMB-W asphalt goes through elastic deformation with small viscosity loss
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