455 research outputs found
Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash
AbstractA novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorptionâdesorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The DublinâRadushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics
Summary of Advances in the Heat-Pulse Technique: Improvements in Measuring Soil Thermal Properties
This essay provides a summary of âAdvances in the Heat-Pulse Technique: Improvements in Measuring Soil Thermal Propertiesâ recently appearing in Methods of Soil Analysis. Series
Numerical assessment of the reduction of specific absorption rate by adding high dielectric materials for fetus MRI at 3 T
The specific absorption rate (SAR) is an important issue to be considered in fetus MRI at 3 T due to the high radiofrequency energy deposited inside the body of pregnant woman. The high dielectric material (HDM) has shown its potential for enhancing B field and reducing SAR in MRI. The aim of this study is to assess the feasibility of SAR reduction by adding an HDM to the fetus MRI. The feasibility of SAR reduction is numerically assessed in this study, using a birdcage coil in transmission loaded with an electromagnetic pregnant woman model in the SEMCAD-EM solver. The HDMs with different geometric arrangements and dielectric constants are manually optimized. The B1+ homogeneity is also considered while calculating the optimized fetus 10 g local SAR among different strategies in the application of HDM. The optimum maximum fetus 10 g local SAR was obtained as 2.25 W/kg, by using two conformal pads placed left and right with the dielectric constant to be 400, reduced by 24.75% compared to that without the HDM. It indicated that the SAR can be significantly reduced with strategic placement of the HDM and the use of HDM may provide a simple, effective and low-cost method for reducing the SAR for the fetus MRI at 3 T
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Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies
Objective: To examine and quantify the potential dose-response relation between fruit and vegetable consumption and risk of all cause, cardiovascular, and cancer mortality. Data sources Medline, Embase, and the Cochrane library searched up to 30 August 2013 without language restrictions. Reference lists of retrieved articles. Study selection Prospective cohort studies that reported risk estimates for all cause, cardiovascular, and cancer mortality by levels of fruit and vegetable consumption. Data synthesis Random effects models were used to calculate pooled hazard ratios and 95% confidence intervals and to incorporate variation between studies. The linear and non-linear dose-response relations were evaluated with data from categories of fruit and vegetable consumption in each study. Results: Sixteen prospective cohort studies were eligible in this meta-analysis. During follow-up periods ranging from 4.6 to 26 years there were 56 423 deaths (11 512 from cardiovascular disease and 16 817 from cancer) among 833 234 participants. Higher consumption of fruit and vegetables was significantly associated with a lower risk of all cause mortality. Pooled hazard ratios of all cause mortality were 0.95 (95% confidence interval 0.92 to 0.98) for an increment of one serving a day of fruit and vegetables (P=0.001), 0.94 (0.90 to 0.98) for fruit (P=0.002), and 0.95 (0.92 to 0.99) for vegetables (P=0.006). There was a threshold around five servings of fruit and vegetables a day, after which the risk of all cause mortality did not reduce further. A significant inverse association was observed for cardiovascular mortality (hazard ratio for each additional serving a day of fruit and vegetables 0.96, 95% confidence interval 0.92 to 0.99), while higher consumption of fruit and vegetables was not appreciably associated with risk of cancer mortality. Conclusions: This meta-analysis provides further evidence that a higher consumption of fruit and vegetables is associated with a lower risk of all cause mortality, particularly cardiovascular mortality
Correction with Backtracking Reduces Hallucination in Summarization
Abstractive summarization aims at generating natural language summaries of a
source document that are succinct while preserving the important elements.
Despite recent advances, neural text summarization models are known to be
susceptible to hallucinating (or more correctly confabulating), that is to
produce summaries with details that are not grounded in the source document. In
this paper, we introduce a simple yet efficient technique, CoBa, to reduce
hallucination in abstractive summarization. The approach is based on two steps:
hallucination detection and mitigation. We show that the former can be achieved
through measuring simple statistics about conditional word probabilities and
distance to context words. Further, we demonstrate that straight-forward
backtracking is surprisingly effective at mitigation. We thoroughly evaluate
the proposed method with prior art on three benchmark datasets for text
summarization. The results show that CoBa is effective and efficient in
reducing hallucination, and offers great adaptability and flexibility
Rethinking Noisy Label Learning in Real-world Annotation Scenarios from the Noise-type Perspective
We investigate the problem of learning with noisy labels in real-world
annotation scenarios, where noise can be categorized into two types: factual
noise and ambiguity noise. To better distinguish these noise types and utilize
their semantics, we propose a novel sample selection-based approach for noisy
label learning, called Proto-semi. Proto-semi initially divides all samples
into the confident and unconfident datasets via warm-up. By leveraging the
confident dataset, prototype vectors are constructed to capture class
characteristics. Subsequently, the distances between the unconfident samples
and the prototype vectors are calculated to facilitate noise classification.
Based on these distances, the labels are either corrected or retained,
resulting in the refinement of the confident and unconfident datasets. Finally,
we introduce a semi-supervised learning method to enhance training. Empirical
evaluations on a real-world annotated dataset substantiate the robustness of
Proto-semi in handling the problem of learning from noisy labels. Meanwhile,
the prototype-based repartitioning strategy is shown to be effective in
mitigating the adverse impact of label noise. Our code and data are available
at https://github.com/fuxiAIlab/ProtoSemi
Some topological indices and graph properties
In this paper, by using the degree sequences of graphs, we present sufficient conditions for a graph to be Hamiltonian, traceable, Hamilton-connected or -connected in light of numerous topological indices such as the eccentric connectivity index, the eccentric distance sum, the connective eccentricity index
Comparative transcriptome profiling of the fertile and sterile flower buds of a dominant genic male sterile line in sesame (Sesamum indicum L.)
Expressions and annotations of the 1502 differentially expressed unigenes in sesame. (XLSX 338 kb
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