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•Cr-free Cu-catalysts were investigated for the highly efficient conversion of furfural.•The high yield of 2-methylfuran was attributed to synergistic effect of metal and the weak ...acid sites.•Interactions of copper-support significantly influence the catalytic performance.•The acidic property of Cu-catalysts was closely related to products selectivity in furfural hydrogenation.
Our work focuses on exploring Cr-free Cu-catalysts for the highly efficient conversion of biomass-derived furfural to value-added bio-fuel 2-methylfuran. Three supported Cu-catalysts (Cu/SiO2, Cu/Al2O3, and Cu/ZnO) were prepared by the typical precipitation method, and Cu/SiO2 catalyst exhibited the best catalytic performance with an 89.5% yield to 2-MF. A series of characteristic results indicated that the high yield of 2-methylfuran on Cu/SiO2 catalyst was assigned to synergistic effect of metal and the weak acid sites. Among them, Cu/ZnO catalyst exhibited maximum furfuryl alcohol selectivity because of the large Cu particles, while Cu/Al2O3 catalyst had low 2-methylfuran selectivity due to the insufficient weak acid sites. For Cu/SiO2 catalyst, the highly dispersed Cu particles and the strong metal-support interaction are propitious to its superior catalytic activity. Therefore, copper species are composed on different supports as a result of the different interaction of metal-support to affect their catalytic activity, while products selectivity is related to the acidic property of catalyst. In addition, temperature programmed desorption of furfural indicated that the adsorption–desorption properties of catalyst surface species would influence the rate of furfural hydrogenation.
Low-temperature efficient hydrogenation of CO bonds in various compounds, which is one of the most important processes for producing fuels and chemicals, is of fundamental interest but remains a ...significant challenge. The primary problem is a lack of heterogeneous catalyst systems that are highly active at ambient or low temperatures. This paper describes an efficient strategy for designing a low-temperature hydrogenation catalyst. Ru nanoparticles supported on reduced graphene oxide (Ru/RGO) show remarkable efficiency for hydrogenation of levulinic acid into γ-valerolactone at temperatures as low as −10 °C. The catalyst is also highly active toward low-temperature hydrogenation of CO bonds in other carbonyl compounds into C–OH bonds, such as furfural, propionaldehyde, 2-pentanone, hydroxyacetone, acetone, acetophenone, cyclohexanone, and benzophenone. X-ray photoelectron spectroscopy and in situ Fourier transform infrared demonstrate that the electron transfer between Ru0 and RGO leads to the formation of an electron-rich state of Ru0 nanoparticles that are highly effective for activating CO bonds.
Received signal strength- (RSS-) based localization has attracted considerable attention for its low cost and easy implementation. In plenty of existing work, sensor positions, which play an ...important role in source localization, are usually assumed perfectly known. Unfortunately, they are often subject to uncertainties, which directly leads to effect on localization result. To tackle this problem, we study the RSS-based source localization with sensor position uncertainty. Sensor position uncertainty will be modeled as two types: Gaussian random variable and unknown nonrandom variable. For either of the models, two semidefinite programming (SDP) methods are proposed, i.e., SDP-1 and SDP-2. The SDP-1 method proceeds from the nonconvex problem with respect to the maximum likelihood (ML) estimation and then obtains an SDP problem using proper approximation and relaxation. The SDP-2 method first transfers the sensor position uncertainties to the source position and then obtains an SDP formulation following a similar idea as in SDP-1 method. Numerical examples demonstrate the performance superiority of the proposed methods, compared to some existing methods assuming perfect sensor position information.
Ethanol synthesis from syngas via dimethyl oxalate (DMO) hydrogenation is of crucial importance for environment- and energy-related applications. Herein, we designed the bifunctional Cu nanoparticle ...(NP) inlaid mesoporous Al2O3 catalyst and first applied it to ethanol synthesis with high efficiency. The catalyst was made based on the spatial restriction strategy by pinning the Cu NPs on mesoporous Al2O3 to conquer the sintering problem and facilitate the stability (>200 h at 270 °C), which has potential values in high-temperature and exothermic reactions. The plentiful pores, highly exposed and properly assembled Cu-acid sites, furnished the catalyst with high ethanol yield (∼94.9%). A structure-sensitive behavior that the intrinsic activity increases with the decreasing NP size was discussed. It was attributed to the change in metal–acid interfacial sites, morphology, and electronic structure and balance of surface Cu0–Cu+ species. The mechanism for DMO hydrogenation to ethanol involving activation of CO, C–O, and O–H bands was also proposed. As cleavage of these bonds is a versatile tool to utilize bioderived molecules (e.g., polyols), the bifunctional catalysts can also be applied to hydrogenolysis of C–O bonds or etherification of O–H groups to produce various chemicals.
The performance evaluation of state estimators for nonlinear regular systems, in which the current measurement only depends on the current state directly, has been widely studied using the Bayesian ...Cramér-Rao lower bound (BCRLB). However, in practice, the measurements of many nonlinear systems are two-adjacent-states dependent (TASD) directly, i.e., the current measurement depends on the current state as well as the most recent previous state directly. In this paper, we first develop the recursive BCRLBs for the prediction and smoothing of nonlinear systems with TASD measurements. A comparison between the recursive BCRLBs for TASD systems and nonlinear regular systems is provided. Then, the recursive BCRLBs for the prediction and smoothing of two special types of TASD systems, in which the original measurement noises are autocorrelated or cross-correlated with the process noises at one time step apart, are presented, respectively. Illustrative examples in radar target tracking show the effectiveness of the proposed recursive BCRLBs for the prediction and smoothing of TASD systems.
Large observational studies have yielded conflicting results regarding whether the use of proton pump inhibitors (PPI) increases the risk of bone diseases. Here, we performed a meta-analysis to ...examine the link between PPI and risk of bone fractures, osteoporosis and bone mineral density (BMD) loss.
We systematically performed a search for published reports on PubMed, EMBASE and the Cochrane Library. We considered articles published in English, and restricted the search to studies on human participants. Studies that reported adjusted Hazard ratio (HR) estimates with 95% confidence intervals (CI) for the associations of interest were included. Data from the articles which can be used to estimate standardized mean difference (SMD) were also obtained and utilized to assess the risk of BMD loss.
Compared with patients not taking PPI, those taking PPI, had the increased risk of developing any-site fractures (HR: 1.30; 95%CI: 1.16 to 1.45), hip fracture (HR:1.22; 95%CI:1.15 to 1.31), spine fracture (HR:1.49; 95%CI:1.31 to 1.68), and osteoporosis (HR:1.23; 95%CI:1.06 to 1.42) based on a random model, but there was no correlation with developing BMD loss in the femoral (SMD: −0.27; 95%CI: −0.62 to 0.09), or in the spine (SMD: −0.06; 95%CI: −0.54 to 0.41).
Results of this meta-analysis suggest that PPI may moderately increase the risk of any-site, hip, spine fracture. Due to the widespread use of PPI and the impact of fractures on human health, clinicians should carefully evaluate the patient condition before prescribing PPI therapy.
Although previous research has provided useful insights into unconventional shale gas resources in recent years, the geochemical and geological characteristics of marine–continental transitional ...shale have not been studied systematically. During the Late Permian, Longtan Formation shales were widely deposited in the Yangtze area of South China. These shales clearly indicate the need to deepen our understanding of marine–continental transitional shales. This study describes the various characteristics of black shales from the Longtan Formation in this area on the basis of a field investigation and relevant laboratory analyses. Longtan shale reservoirs, with a thickness and burial depth range of 20–650 and 800–2400 m, respectively, are usually interbedded with coal and compact sandstone reservoirs due to their special sedimentary environment. Geochemical analysis of the samples of Longtan shales from seven wells in the Yangtze area indicates the presence of high organic matters (OMs), with a total organic carbon content in the range of 0.85%–35.7% (average of 7.33%) but low hydrocarbon genetic potential (S2) with a value below 3 mg HC/g rock. The analysis of carbon isotopes and organic macerals demonstrates that the investigated samples mainly contain type III kerogen. Data from gas chromatography and gas chromatography-mass spectrometry analyses illustrate a weakly oxidizing to a weakly reducing environment, with most organic materials originating from algal-bacterial organisms and terrestrial plants. The terrestrial plants contribute significantly to the OM. The Longtan shales are thermally over-matured, and they have entered the dry-gas generation window according to Ro, production index data, and biomarker maturity ratios. X-ray diffraction analyses show that the content of brittle minerals of the Longtan shales is generally lower than that of marine shales in North America. The Longtan shales show a high clay content averaging 60.32 wt% and low calcite mineral content averaging 3.73 wt%. Field emission scanning electron microscopy shows that various types of nanometer-to micrometer-scale pores, including interparticle and intraparticle pores, OM pores, and microfractures, are well developed in the shales. Generally, high OM abundance, thermal evolution degree, clay mineral content, and pore space (porosity of 0.56%–10.6%) positively influence shale gas content (1.0%–3.8%). However, high clay content and variable reservoir thickness hinder the successful production of shale gas.
•Highly organic-rich, thermally over-matured and type III kerogen are developed.•Mixed organic matters originate from weakly oxidizing to weakly reducing environment.•Rich clays will contribute for gas sorption but hinder reservoir fracturing.•Various kinds of shale pores within nanometer to micrometer scale are well developed.•Longtan shales show good potential of shale gas but great production difficulty.
Mutations in FBN1 have been well identified in syndromic aortic dissection (AD) and familial thoracic aortic aneurysms and dissections. However, whether mutations of FBN1 contribute to sporadic ...non-syndromic AD and the characteristics of mutations remain unknown. Using next-generation-sequencing technology, FBN1 was sequenced in a total of 702 sporadic cases (including 687 of non-syndromic AD and 15 of sporadic Marfan syndrome with aortic event, and 527 normal controls). For the sporadic non-syndromic AD cohort, we found 26 variants in 27 patients (18 with missense, 2 frameshift, 1 initiation codon mutation, 3 nonsense and 3 splice site mutations). The prevalence of variants was significantly high in the sporadic non-syndromic AD cohort (27/687, 3.9%). The patients with FBN1 mutations were younger, suffered from fewer risk factors such as hypertension and smoking, and were less gender partitioned than non-FBN1-mutation AD patients. The mutations were spread along the FBN1 gene in our sporadic non-syndromic AD cohort and mutation locations are not different between non-syndromic and syndromic patients. These results demonstrate that the deleterious mutations in FBN1 largely contribute to pathogenesis of sporadic non-syndromic AD, which expands our knowledge of FBN1 variants and the genetic basis and pathology of AD.
The composition characteristics of altered coals in the Huaibei Coalfield, China, was investigated through a comparative analysis between altered and unaffected coals from the Wolonghu, Taoyuan and ...Renlou coal mines. Results indicated that the altered coals in Wolonghu coal mine are mostly anthracite coals, with a maximum vitrinite reflectance of 1.6–3.9% (average of 2.9%). Coals from Wolonghu coal mine were mainly consisted of vitrinite (66.2–97.0%), followed by inertinite (2.0–4.0%) and exinite (0.4–6.9%). Differences in volatile matter content were observed between the altered coals in Wolonghu coal mine and unaffected coals from neighboring coal mines, implying that the chemical composition and maturity of coals were changed after magmatic alteration. In addition, differences in hydrogen element were noted among the coals from Wolonghu, Renlou and Taoyuan coal mines, and the phenomenon of “deficient in hydrogen element” was observed in Wolonghu coals. The aliphatic hydrocarbon structure parameters suggested that the aliphatic chain lengths of Wolonghu coals are shorter than those of coal samples from the Renlou and Taoyuan coal mines. In addition, maturity is positively correlated with hydrogen enrichment degree, but negatively related with aliphatic hydrocarbon structure. Coals from Renlou and Taoyuan coal mines showed great weight loss with various heating rates at temperatures of 0–1000 °C, whereas those from Wolonghu coal mine had less weight loss.
Variations in pore types, the complexity of pore structures, and strong heterogeneity complicate the thorough characterization of pore networks in marine–continental shales. In this study, a novel 2D ...image processing method was proposed, expounded, and verified to clarify the geometrical morphologies, formation mechanisms, the size distributions, proportions and the fractal characteristics of different types of pores in marine–continental shales. Six types of pores (inter-particle, intra-particle, organic matter (OM), inter-crystalline, dissolved pores, and micro-fractures) were classified and morphologically characterized. The different types of shale pores had distinct relatively restricted morphologies, formation mechanisms, and size ranges. Nano- and micron-sized pores were controlled by OM pores and micro-fractures, with the size ranging of 6–80 nm and 200–350 nm and 6–10 μm, respectively. Furthermore, the fractal dimension characteristics were investigated on the basis of the 2D binary images, and the results were verified by the fractal findings obtained from the N2 adsorption data. These fracture dimension results demonstrated that the Longtan shale pore structures had strong complexity and heterogeneity, which was strongly and positively controlled by micro-fractures, inter-crystalline and OM pores. In addition, the total organic carbon content strongly and positively influences the development and anisotropy of the nanoscopic pores, which were dominated by OM pores; while the clay minerals content has a minor effect on the total pore development and heterogeneity of shales but a significant effect on the dissolved pore development of shales, whereas brittle minerals inhibit total pore development and heterogeneity of shales but contribute greatly to the development of the inter-crystalline pores.
•A novel method was used to resolve structures of different types of shale pores.•Morphology, formation mechanism and size of multi-type pores were investigated.•Fractal characteristics were analyzed by SEM images and N2 gas absorption data.•Shale components discriminatively dominate various types of pore development.•OMs and clays are the key components controlling the pore volume and heterogeneity.
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