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As one of the research hotspots in the field of speech recognition, content-based speech retrieval algorithms can detect speech information with the same content features, which improves computer intelligence while reducing labor costs, and thus have been widely used. Although most of the current speech content retrieval algorithms can guarantee excellent retrieval performance for small-scale speech retrieval work, the performance of the above algorithms is greatly reduced under the constraints of large speech data storage space and high content redundancy. In order to solve the above problems, a high-performance speech BioHashing retrieval algorithm based on audio segmentation is proposed in this paper. The algorithm is divided into an offline pre-processing phase and an online retrieval phase, The offline pre-processing stage converts the speech data into BioHashing sequences with speech content characteristics. In this process, first of all, the Power-Normalized Cepstral Coefficients (PNCC) features of the speech data are extracted and biometric templates with single mapping keys are constructed according to the PNCC features, obtaining BioHashing sequences. Then, slice the original speeches into short-time audio segments according to the proposed audio segmentation algorithm, and the hash reconstruction operation is performed on the BioHashing sequences to obtain the reconstructed Hashing sequences for online retrieval. The online search phase responds to the users' query requests, just find the hash index that matches the query hash sequence from the BioHashing index table, and will the standardized editing distance (SED) to the closest 1 value corresponding to the hash index as the retrieval result back to the user. The experimental results show that the reconstructed hash sequences obtained after removing the silent redundant segments have better robustness and discrimination. Moreover, the algorithm achieves 100% retrieval accuracy for the original speech clips, and the average retrieval time is only 0.0157 s, which shows that the algorithm has good retrieval performance and can meet the needs of speech retrieval in various environments. • The audio segmentation algorithm is applied to speech retrieval. • Using normalized editing distances to match hash sequences of different lengths. • The machine learning classification algorithm is applied to the speech feature data. • Constructing revocable biometric templates, implemented secondary distribution retrieval. [ABSTRACT FROM AUTHOR]

This work is concerned with a mathematical study of ill-posed backward evolution equations associated with densely defined linear differential operators in Banach spaces. A general approach is presented to investigate the convergence and stability of a class of regularized solutions for ill-posed backward evolution equations associated with sectorial or half-strip operators. Generalized concepts of qualification pairs and index functions are introduced to characterize the explicit convergence rates of the concerned regularized solutions. Applications of our results to general backward evolution equations are also investigated. [ABSTRACT FROM AUTHOR]

Biochar can be an effective amendment for immobilizing heavy metals in contaminated soils but has variable effects depending on its chemical and physical properties and those of the treated soil. To investigate the range of biochar's effects on heavy metal accumulation in plants in responses to the variation of soil, biochar and plant, we carried out a meta-analysis of the literature that was published before March 2016. A total of 1298 independent observations were collected from 74 published papers. Results showed that across all studies, biochar addition to soils resulted in average decreases of 38, 39, 25 and 17%, respectively, in the accumulation of Cd, Pb, Cu and Zn in plant tissues. The effect of biochar on heavy metal concentrations in plants varied depending on soil properties, biochar type, plant species, and metal contaminants. The largest decreases in plant heavy metal concentrations occurred in coarse-textured soils amended with biochar. Biochar had a relatively small effect on plant tissue Pb concentrations, but a large effect on plant Cu concentrations when applied to alkaline soils. Plant uptake of Pb, Cu and Zn was less in soils with higher organic carbon contents. Manure-derived biochar was the most effective for reducing Cd and Pb concentrations in plants as compared to biochars derived from other feedstock. Biochar having a high pH and used at high application rates resulted in greater decreases in plant heavy metal uptake. The meta-analysis provides useful guidelines on the range of effects that can be anticipated for different biochar materials in different plant-soil systems. [ABSTRACT FROM AUTHOR]

Green tea and its food-grade extracts are widely used in food technology because of their rich chemical composition. Our previous study found that dynamic extraction tea extract exhibited higher quality than conventional extraction methods. Thus, the objective of this study was to develop a high-efficiency, dynamic extraction method to improve extraction efficiency and the sensory quality of green tea. The effects of dynamic extraction conditions on the chemical composition and sensory quality of green tea extract were investigated with sensory and physicochemical analysis. Extraction temperature and flow rate strongly affected the taste of green tea extract. The tea extracts were obtained with high-umami or high yield by optimized extraction conditions. The triphasic dynamic (column) extraction yield was improved by 11.22% compared with the static extraction. The results can help to understand the influences of dynamic extraction conditions on the quality of tea extract and to optimize the extraction method of tea extract. • A dynamic extraction to improve extraction efficiency and the sensory quality. • Smaller particle-size leaves increased concentrations of the chemical components. • Suitable conditions were found to produce high-umami extract with good quality. • Yield of dynamic extraction was improved 11.22% compared with static extraction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three new cadinene-type sesquiterpene dimers, named hibisceusones A-C, were isolated from H. tiliaceus. • Dimeric skeletons were formed from a unique 1,4-dioxane ring for the first time in natural products. • Compound 2 exhibited promising anti-TNBC activities by inducing the apoptosis of MDA-MB-231 cells by inhibiting the PI3Kα pathway. Three new cadinane-type sesquiterpenoid dimeric diastereomers (1 – 3) named hibisceusones A-C were obtained from the infected stems of Hibiscus tiliaceus. The structures were determined by NMR spectroscopy and MS techniques, and the absolute configurations were assigned by ECD and single-crystal X-ray diffraction techniques. Compounds 1 – 3 are diastereomers, and contain a 1,4-dioxane ring linearly fused to different cadinane-type polycyclic skeletons. This is the first time that such a structure has been identified in natural products. Compounds 1 – 3 exhibited cytotoxic activities, and 2 showed a significantly high anti-triple-negative breast cancer (TNBC) effect. The anti-cancer effect of compound 2 was 3–4 fold higher than that of 1 and 3. The anti-cancer effect was generated via the induction of the apoptosis of the MDA-MB-231 cells by inhibiting the PI3Kα pathway. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with a nonlinear delay differential inclusion of evolution type involving m-dissipative operator and source term of multi-valued type in a Banach space. Under rather mild conditions, the -structure of -solution set is studied on compact intervals, which is then used to obtain the -property on non-compact intervals. Secondly, the result about the structure is furthermore employed to show the existence of -solutions for the inclusion (mentioned above) subject to nonlocal condition defined on right half-line. No nonexpansive condition on nonlocal function is needed. As samples of applications, we consider a partial differential inclusion with time delay and then with nonlocal condition at the end of the paper. [Copyright &y& Elsevier]

Abstract: The site requirements for the methane total combustion, partial oxidation, and decomposition on LaFeO3 perovskite catalysts during the chemical looping process were addressed by a kinetic study through varying the O content and the crystal size. The exchange between the surface oxygen and lattice oxygen is rapid, and the active sites of Fe associated with the surface oxygen are highly dynamic in nature, which depends on the amount of O in the perovskite during reaction and the O binding energy. Three types of active sites are identified where Fe atoms highly coordinated with O lead to total combustion of methane, Fe moderately coordinated with O leads to partial oxidation, and Fe highly coordinated with vacancy sites leads to carbon formation. The crystal size of LaFeO3 perovskite plays a significant role in determining the O binding energy and their catalytic properties on the partial oxidation of methane by the chemical looping process. Different crystal sizes of perovskites have been obtained using various preparation methods. Larger crystal has a high selectivity to synthesis gas and high capacity of O removal, due to a lower O–Fe bond energy, as indicated by a smaller band gap measured by UV–Vis absorption spectroscopy. Nearly pure synthesis gas was produced by methane partial oxidation using chemical looping on LaFeO3 by tuning the surface O coverage through controlling the oxidation degree in the oxidation step. [Copyright &y& Elsevier]

Abstract: Of concern are the Cauchy problems for linear and semilinear time fractional evolution equations involving in the linear part, a linear operator A whose resolvent satisfies the estimate of growth −γ in a sector of the complex plane, which occurs when one considers, for instance, the partial differential operators in the limit domain of dumb-bell with a thin handle or in the space of Hölder continuous functions. By constructing a pair of families of operators in terms of the generalized Mittag-Leffler-type functions and the resolvent operators associated with A (for the first time), and a deep analysis on the properties for these families, we obtain the existence and uniqueness of mild solutions and classical solutions to the Cauchy problems. Moreover, we present three examples to illustrate the feasibility of our results. [Copyright &y& Elsevier]

Abstract: The effect of the crystal size of Ni on the growth of carbon nanofibers (CNFs) was studied in a tapered oscillating element microbalance reactor. Small Ni crystals yield a low growth rate and fast deactivation and thus a low final yield of CNF. Large Ni crystals reduce the growth rate because of low surface area. An optimum growth rate and yield of carbon nanofibers can be achieved on optimally sized Ni crystals (around 34 nm). A model has been proposed for interpreting the kinetic effects of the Ni crystal size based on a detailed mechanism of the carbon nanofiber growth. The reduced coking rate on a small-sized Ni crystal is a result of increased saturation concentration of CNF and thus a low driving force for carbon diffusion through the Ni crystals. As a consequence, the surface coverage of carbon increases, which enhances the formation of encapsulating carbon and thus the deactivation. Both the low initial coking rate and the fast deactivation result in a low yield of carbon nanofibers on small-sized crystals. The results also indicate that hydrogen has a significant effect on the formation of CNF, and an optimum partial pressure of hydrogen exists for the CNF growth. [Copyright &y& Elsevier]

[Display omitted] • In-doped amino-functionalized UiO-66 Zr-MOFs are synthesized by one-pot reaction. • Amino groups reduce band gap by lifting valence band maximum. • In doping facilities LMCT process by inducing oxygen vacancies. • aU(Zr/In) exhibits the excellent photoreduction activity of CO 2 to CO. Metal organic frameworks (MOFs) with high porosity and highly tunable physical/chemical properties can serve as heterogeneous catalysts for CO 2 photoreduction, but the application is hindered by the large band gap (E g) and insufficient ligand-to-metal charge transfer (LMCT). In this study, a simple one-pot solvothermal strategy is proposed to prepare an amino-functionalized MOF (aU(Zr/In)) featuring an amino-functionalizing ligand linker and In-doped Zr-oxo clusters, which enables efficient CO 2 reduction driven with visible light. The amino functionalization leads to a significant reduction of E g as well as a charge redistribution of the framework, allowing the absorption of visible light and the efficient separation of photogenerated carriers. Furthermore, the incorporation of In not only promotes the LMCT process by creating oxygen vacancies in Zr-oxo clusters, but also greatly lowers the energy barrier of the intermediates for CO 2 -to-CO conversion. With the synergistic effects of the amino groups and the In dopants, the optimized aU(Zr/In) exhibits a CO production rate of 37.58 ± 1.06 μmol g-1 h−1, outperforming the isostructural University of Oslo-66- and Material of Institute Lavoisier-125-based photocatalysts. Our work demonstrates the potential of modifying MOFs with ligands and heteroatom dopants in metal-oxo clusters for solar energy conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ir – TiO 2 interaction was dependent on Ir sizes and crystal plane of TiO 2. • Both activity and selectivity of the catalysts increased as the Ir size grew from single atom to nanoparticle. • End-on C O adsorption of crotonaldehyde was favored at the Ir-TiO x interface for Ir nanoparticles. • Crotonaldehyde adsorption geometry depends on H coverage on the catalyst surface. For the supported catalysts for the selective hydrogenation of α, β - unsaturated aldehyde with H 2 , tailoring of metal - support interfacial effect to improve reaction performance is a significant but challenging subject. In this work, we regulated both the size regimes of the Ir deposits (single atom, nanocluster and nanoparticle) and the crystal plane of anatase TiO 2 (TiO 2 (1 0 1), TiO 2 (1 0 0) and TiO 2 (0 0 1)) so as to alter the Ir-TiO x interfacial properties, in order to unravel reaction mechanism of selective hydrogenation of crotonaldehyde over the Ir/TiO 2 catalysts. Both the activity and selectivity to crotyl alcohol increased as the Ir size grew from single atom to nanoparticle, ascribed to high Ir0 content, high concentration of surface defects and prominent H-spillover effect on the Ir nanoparticles. Moreover, the in situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations demonstrated that an end-on C O adsorption mode for crotonaldehyde molecule was favored at the Ir-TiO x interface particularly at high H coverage, which thus facilitated the hydrogenation of C O bond to form crotyl alcohol. Moreover, the highest reactivity of the Ir nanoparticles was evidenced by the lowest reaction barrier. These results explicitly demonstrate that larger metal nanoparticles and adsorption geometry of the reactant at the metal - support interface are vital for improved catalytic performance, which would shed light on the ingenious catalyst design. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of ligand coordination on the mechanism and regioselectivity is investigated. • The free energy surfaces differ greatly for the bidentate and tridentate nitrogen ligands. • The electrostatics and orbital interactions are the dominant factors regulating the regioselectivity. The 3d transition metal-catalyzed cyclization of enynes provides a sustainable and useful strategy for the construction of cyclic compounds. Controlling the regioselectivity is a central challenge for the hydrofunctionalization of multiply unsaturated substrates such as 1,6-enynes. Herein, we report a computational mechanistic study of the cobalt-catalyzed hydroboration/cyclization of 1,6-enynes in the presence of three representative ligands including bidentate nitrogen ligand and phosphine ligand as well as tridentate nitrogen-based ligand. A detailed analysis is carried out on the ligand-substrate interactions to understand the effect of ligand coordination on the mechanism and regioselectivity. Our results indicate that although the initial catalyst-substrate complexes adopt the pseudo-trigonal bipyramidal geometries for the two nitrogen-based ligands, there is a remarkable difference in the free energy surfaces. The steric repulsions and hydrogen bonding interactions between the substrate and the ligand play important roles in regulating the competing migration insertion. Energy decomposition analyses are further performed for the subsequent σ-bond metathesis to illustrate the impacts of steric and electronic effects on the regioselectivity and the electrostatics and orbital interactions are disclosed to be the dominant factors. This work provides a deeper understanding of the specific structural and electronic properties of the cobalt complexes and their potential influences on the reactivity and selectivity. [ABSTRACT FROM AUTHOR]

Sepiolite (SEP) is a clay mineral with great potential to stabilize soil heavy metals. A two-year field experiment was conducted to explore the optimum use of SEP to immobilize soil Cd and to promote the consumption safety of rice grown in a typical paddy field in Southern China. SEP was applied once or twice over the two-year study at three levels (0.1, 0.5, and 1%, w/w) before rice planting. The results showed that SEP effectively reduced rice grain Cd concentrations by 47–49% in the first year and by 44–50% in the second year due to the residue effect. Application of SEP for two consecutive years reduced the rice grain Cd concentration by up to 75%, achieving a safe level (<0.2 mg kg−1). SEP also reduced Zn concentrations in rice grains (by 6–10%), while the Cd/Zn ratios of rice grains were decreased by 24–72% over the two years, implying it was much safer for consumption. SEP significantly increased the soil pH (0.9–1.8 units) and available phosphorus, and it reduced the soil available Cd (by 20–95%) and Zn concentrations (by 30–99%). In brief, SEP effectively stabilized soil Cd and reduced uptake by rice; the effect was dose-dependent and 0.5% (w/w) was optimum in the present study. The main mechanism of SEP to stabilize soil Cd is the increase in soil pH analogous to liming. This study shows that SEP application can be an efficient way to remediate Cd contaminated rice paddies and fulfill the goal of safe production of rice and thereby reduce the health risks associated with consuming rice. Image 1 • Sepiolite reduced soil Cd availability and translocation in rice plants. • Sepiolite reduced Cd concentration and Cd/Zn ratio in rice grain. • The effect of sepiolite is dose-dependent with 0.5% being the optimal dose. • Sepiolite is effective to remediate Cd contaminated soil and improve rice safety. [ABSTRACT FROM AUTHOR]

An efficient S-scheme photocatalyst based on 3D flower-like Fe-doped In 2 S 3 /Fe 3 S 4 hetero-microspheres assembled from interconnected nanosheets was synthesized via a facile one-pot solvothermal reaction, which exhibits the enhanced interfacial electric field and boosted visible-light-driven CO 2 reduction. [Display omitted] S-scheme heterojunctions hold great potential for CO 2 photoreduction into solar fuels, but their activities are severely limited by the low efficiency of interfacial charge transfer. In this work, a facile one-pot solvothermal reaction has been developed to dope Fe into flower-like In 2 S 3 /Fe 3 S 4 hetero-microspheres (Fe-In 2 S 3 /Fe 3 S 4 HMSs), which are demonstrated as an efficient S-scheme photocatalyst for visible-light-driven CO 2 photoreduction. The doping of Fe not only reduces the bandgap of In 2 S 3 and thus extends the optical response to the visible-light region, but also increases the densities of donors and sulfur vacancies, which leads to an elevated Fermi level (E f). The difference of E f between In 2 S 3 and Fe 3 S 4 is enlarged and their band bending at the interface is therefore enhanced, which results in promoted carriers transfer in the S-scheme pathway due to the reinforced interfacial electric field. Moreover, Fe-doped In 2 S 3 reduces the formation energy of the *CO intermediate, which thermodynamically favors the CO evolution at the surface. As a result, the Fe-In 2 S 3 /Fe 3 S 4 HMSs exhibit a significantly boosted CO 2 photoreduction activity in comparison with bare In 2 S 3 and Fe-In 2 S 3 samples. This work demonstrates the great potential of heteroatom-engineered S-scheme photocatalysts for CO 2 photoreduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ X-ray absorption spectroscopy (XAS) and operando UV–vis-NIR measurements. • Monitoring dynamic changing Cu active sites in the transient and steady state. • Correlating the Cu oxidation state with performance under the real reaction conditions. • The influence of La promoter studied by in situ XAS. The oxidation state of Cu species in ethylene oxychlorination is strongly correlated with catalytic performance. CuCl 2 and CuCl have been identified as the primary active sites in the reduction and oxidation step, respectively, according to a redox-type mechanism. The distribution of the active sites is governed by the kinetic equilibrium of the reduction, oxidation, and hydrochlorination rates at steady-state. Herein, in situ X-ray absorption spectroscopy (XAS) and operando ultraviolet–visible and near-infrared spectroscopy (UV–vis-NIR) were utilized to quantify the dynamic changes of the Cu active sites over the La-doped CuCl 2 / γ -Al 2 O 3 in transient and steady-state experiments. A higher CuCl 2 concentration plays a key role in dominating the higher activity, EDC selectivity, and stability. The in situ XAS result evidenced La was considered as a structural additive to increase the reducibility of the active CuCl 2 and modify the catalytic performance instead of directly involving the reduction-oxidation cycle. A deeper understanding of the complex role of the active species and promoter in the CuCl 2 / γ -Al 2 O 3 based-catalysts for ethylene oxychlorination was obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low H 2 dissociation barrier is obtained using N, S-doped Co single atom catalyst (Co-N 3 SN-def1); • Frustrated Lewis pair comprised of Co and pyridinic N sites facilitate the H 2 dissociation; • H transfer via the solvent water is the main diffusion pathway; • Moderate H adsorption strength at pyridinic N site contributes to the low breaking barrier of N-O bond in nitrobenzene. The limitation of isolated metal active sites in single atom catalysts (SAC) hinder their application in hydrogenation reactions, necessitating the creation of additional active site beyond the metal site. This study introduces pyridinic N and S atoms into the N/C sheet, optimally adjusting the local environment of the Co site. This adjustment synergistically enhances H 2 activation, H diffusion, and promotes the hydrogenation of nitrobenzene into aniline. The sterically hindered Co acidic site and N basic site, known as frustrated Lewis pairs, in defect-containing Co-N 3 SN-def1 model cooperatively facilitate the highly efficient cleavage of the H 2 molecule with a barrier of only 0.37 eV. The findings suggest that the pyridinic N site in the Co-N 3 SN-def1 model acts as a reservoir for *H, significantly contributing to the enhanced activity for the hydrogenation of nitrobenzene. The mechanism unveiled in this study offers valuable insights for designing efficient heterogeneous catalysts for target hydrogenation reactions. [ABSTRACT FROM AUTHOR]

Moderate WO x surface density of Ni/WO x -ZrO 2 with higher Brønsted/Lewis acid sites ratio enhances LDPE hydrocracking and obtains the maximum liquid yield. [Display omitted] • The non-noble Ni catalysts achieves the LDPE hydrocracking process under a mild condition. • The Ni/WO x -Zr catalysts achieves 100 % LDPE conversion with 76.9 % liquid yield. • The WO x surface density shows a volcanic-shape relationship with the B/L ratio of catalyst. • The LDPE hydrocracking performance has a linear relationship with the B/L ratio of catalyst. Chemical upcycling through catalytic hydrocracking to fuels has potential to mitigate the serious environmental issues caused by plastic waste. Herein, non-noble tungstate-zirconia supported nickel catalyst (Ni/WO x -ZrO 2) with tunable Brønsted/Lewis (B/L) ratio was firstly proposed for the hydrocracking of low-density polyethylene (LDPE), which achieves hydrogenation/dehydrogenation on Ni sites and cracking/isomerization on WO x -ZrO 2 , respectively. Excellent 100 % LDPE conversion with 76.9 % liquid yield was achieved, which is comparable to noble Ru-based and Pt-based catalysts. Quantitative linear relationship between B/L ratio and hydrocracking performance was established, and the key to boost performance was keenly controlling the volcanic-shape relationship between surface WO x density and B/L ratio of catalyst. Moderate WO x surface density with higher B/L ratio enhances LDPE hydrocracking, and inhibits the hydrogenation of the primary products. However, excessive WO x polymerized and formed WO 3 crystals, compensating acid sites and inhibiting LDPE hydrocracking. This work is of prime scientific and industrial significance to the rational design of catalysts for industrial plastic hydrocracking. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-precious intermetallic compound catalysts for propane dehydrogenation. • Scaling relations are established using formation energies over terraces and steps. • Descriptor-based microkinetic analysis is carried out to obtain volcano curves. • Fe 3 Ga 1 is a good catalyst candidate with improved catalytic performance. By using a descriptor-based microkinetic analysis combined with results from density functional theory calculations over eight transition-metal (including Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) terrace and stepped surfaces, intermetallic compounds have been screened to search for inexpensive and environmentally friendly propane dehydrogenation (PDH) catalysts with enhanced catalytic performance. Based on the scaling relations, the formation energies of ethyl on terrace and methylidyne on stepped surfaces are identified as two descriptors to represent the energetics of other reaction intermediates and transition sates. The derived PDH activity and propylene selectivity volcano curves not only provide a rational interpretation of the previously experimentally reported catalyst candidates, but also predict several unexpected binary combinations by screening 1482 A 3 B 1 and 741 A 1 B 1 intermetallic compounds. The non-precious Fe 3 Ga 1 is then synthesized and evaluated. Its improved propylene selectivity and catalytic stability with respect to those of the Pt catalyst validates the theoretical predictions experimentally. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atomically dispersed Pt-rTiO 2 catalyst shows good catalytic performance for PDH. • Single and dual Pt atoms can be tightly held by vacancies created on reduced TiO 2. • Dual-Pt-atom structure is the active ensemble for the C H bond activation. Tailoring atomically dispersed catalysts by various methods has been the subject of intense current research in heterogeneous catalysis. In this work, the structural stability and propane dehydrogenation performance of Pt-TiO 2 catalysts with single, dual, and triple Pt atoms doped on the reduced TiO 2 surface have been examined. Experimental results indicate the atomically dispersed Pt is thermally very stable and shows exceptionally high activity (TOF propane = 4.93 s−1) and selectivity (∼98.5 %) for the dehydrogenation reaction. The recently developed machine-learning-based SSW-NN method is then employed to explore the global potential energy surface of the atomically dispersed Pt atom-doped TiO 2 , which suggests that the single and dual Pt atoms can be tightly held by the vacancies created on the reduced transition-metal oxide, as confirmed by DFT + U calculated energetics. After that, advanced characterization techniques are used in conjunction with microkinetic analysis to establish the quantitative structure–activity relationships. It is found that the dual-Pt-atom structure with two Pt atoms embedded in adjacent Ti and O vacancies is the only active ensemble that dramatically promotes the C H bond activation and hydrogen recombination, as compared to single Pt atoms accommodated by either Ti or O vacancies. These results provide new and direct evidence in support of the idea that specific function can be imparted to specific active sites by tuning their coordination environments, which makes it possible to tailor the catalytic properties of metal oxides to a particular reaction such as propane dehydrogenation. [ABSTRACT FROM AUTHOR]

• A 20-fold increase of catalytic activity via engineering the Pt-carbon interactions. • The electron transfer and interfacial bonding vary with the carbon support. • Pt/p-CNF shows the highest Pt binding energy with the least Pt-O-C linkages. • n EWG /n EDG is identified as a good descriptor of Pt/carbon catalyst. Understanding the metal-support interactions in heterogeneous catalysis is critical yet complicated to tailor-design the catalysts with desirable properties. Exemplified with Pt-catalyzed ammonia borane (AB) hydrolysis, a dramatic increase of 20 folds in the catalytic activity is achieved by engineering the Pt-carbon interactions via adopting four different carbon materials (AC, CNT, f-CNF and p-CNF) as the catalyst supports. Multiple characterization techniques reveal that the Pt-carbon electronic interactions, including electron transfer and interfacial bonding, are deemed to be mainly responsible for the remarkable enhancement in the hydrogen generation rate. The molar ratio of electron-withdrawing group to electron-donating group (n EWG /n EDG) is further identified as a descriptor of catalyst in terms of Pt binding energy, which exhibits an almost linear relationship with the catalytic activity. Moreover, a comparison of Pt catalyst pre-treatments, i.e., H 2 and AB reduction as well as Ar calcination, suggests that the Pt-O-C linkages within the Pt-carbon interactions are highly stable yet inferior to this reaction. As a result, combining the merits of the highest Pt binding energy as well as the minimum Pt-O-C linkages, the Pt/p-CNF delivers the highest catalytic activity. The insights presented here could shed new lights on the nature of Pt-carbon interactions, which could be extended to the design and manipulation of other metal-carbon catalysts. [ABSTRACT FROM AUTHOR]

• The PDDA and PVP co-functionalized CNT has been developed to support Pt catalyst. • A combined kinetics analysis, DFT calculations with multiple characterizations is conducted. • The co-functionalization improves the quantity (N i) and quality (TOF i) of Pt active sites. • The catalyst exhibits significantly enhanced H 2 generation activity and durability. Decorating the catalyst support with organic moieties to integrate multiple functionalities into metal particles offers a unique platform to promote the catalytic performance. Here, we report a mechanism-driven strategy to functionalize CNT with dual polymers, endowing the supported Pt catalyst with simultaneously enhanced hydrogen generation activity and durability. Kinetics analysis, multiple characterization and DFT calculations reveal that the PDDA acts as electron-acceptor to capture electrons from the Pt particles toward strengthened adsorption of reactants, while the PVP acts as structure-directing agent to induce the catalyst morphology evolution with a preferential exposure of Pt(1 1 1) active sites. Such electronic and geometric synergy by co-functionalizing PDDA and PVP gives rise to a 3-fold increase in the hydrogen generation activity, together with remarkably improved catalytic durability due to the suppressed adsorption of B(OH) 4 − over the Pt(1 1 1). The strategy reported here might shed new lights on establishing the functionalization protocols to design carbon supported metal catalysts with the targeted properties. [ABSTRACT FROM AUTHOR]

Compared with the clarification method of adding Ca(OH) 2 and the traditional heating method, membrane filtration without adding Ca(OH) 2 and vacuum heating affect the aroma of brown sugar processing by reducing cations, pH and heating temperature. HS-SPME-GC-MS were used to extract and analyze volatiles formed in the production process of brown sugar (obtained by different clarification methods and heating methods), and aroma attributes were analyzed via quantitative descriptive analysis. The results showed that the green and fruity notes were higher in the brown sugar obtained by vacuum heating, especially for the samples without adding Ca(OH) 2 ; the roasted and caramel notes were enhanced by high-temperature. Meanwhile, the aroma attributes had the same tendency as the odorants. Sugarcane juice and syrup had similar volatiles compared to brown sugar. These data indicate that membrane filtration without adding Ca(OH) 2 and vacuum heating provided more fruity and green notes to brown sugar and enriched the brown sugar aroma. • GC–MS showed phenols significantly increased by vacuum heating. • Sensory profiling showed vacuum heating increased the green and fruity notes. • The samples were divided into three groups according to volatiles. • Sugarcane juice and syrup had similar volatiles. • There were more alcohols in sugarcane juice and syrups without adding Ca(OH) 2. [ABSTRACT FROM AUTHOR]

Increasing the utilization efficiency of noble metals by the synergy with less expensive metals is an important yet challenging issue in heterogeneous catalysis. Herein, exemplified with Pt-catalyzed hydrolytic dehydrogenation of ammonia borane, partial substitution of the Pt catalysts by over 11 times less expensive Ru is studied to obtain highly efficient and cost-effective Pt-based catalysts. It is observed that the Pt-Ru bimetallic catalysts, especially Pt 0.5 Ru 0.5 /CNT, deliver higher hydrogen generation activity and durability than the Pt/CNT and Ru/CNT catalysts, indicating a remarkable Pt-Ru synergy. The underlying nature of this synergy is elucidated by combining kinetic and isotopic analyses with multiple techniques such as HAADF-STEM, EDX, XRD, H 2 -TPR, HRTEM, XPS and ICP-AES. The appropriate activation energy and entropy of activation for the reaction are mainly responsible for the highly active Pt 0.5 Ru 0.5 /CNT catalyst, and a volcano-shaped relationship for the reactivity of these five catalysts as a function of entropy of activation is proposed. The insights revealed here might guide the rational design of catalysts for this reaction, and the methodology could be extended to unravel the nature of other bi- or multi-metallic catalysts. [ABSTRACT FROM AUTHOR]

The calculation accuracy of a solid–liquid two-phase flow numerical simulation is related directly to the reliability of the results obtained. The interphase drag force significantly affects the calculation results of the solid concentration distribution of suspended-load sediment solid–liquid two-phase flow. However, the conventional Wen–Yu drag force model is obtained by adding solid concentration to the standard drag force coefficient curves. The model does not consider the influence of turbulence, which is a comprehensive reflection of particle inertia and liquid turbulence intensity. To improve the calculation accuracy of the Wen–Yu model, the particle inertia and turbulence intensity factors are introduced to express the comprehensive influence of the particle inertia and liquid turbulent intensity on the drag force coefficient for the suspended-load sediment solid–liquid two-phase flow. The turbulence modification function preliminary expression is determined and further modified to improve the calculation accuracy for a particle Reynolds number of less than 100 by combining experimental data and the least square method through experiments and theoretical research. Then, the final expression of the turbulence modification function is proposed to help modify the drag force coefficient of the Wen–Yu model, and finally establish the modified turbulence effect (MTE)-Wen–Yu drag force modification model. The calculations for the suspended-load sediment solid–liquid two-phase flow in the circular tubes show that the solid-phase concentration values calculated by the MTE-Wen–Yu drag force model are considerably closer to the experimental results than those obtained by the Wen–Yu drag force model in the suspended-load sediment solid–liquid two-phase flow calculation for different inlet velocities, inlet solid concentrations, and particle diameters. Hence, the calculation accuracy of the MTE-Wen–Yu model is higher than that of the Wen–Yu drag force model. The calculation precision of the solid-phase concentration distribution calculated using the MTE-Wen–Yu drag force model decreases with the increase in particle diameter owing to the high quality and large inertia of large particles. Therefore, it is more suitable for the numerical simulation of suspended-load sediment solid–liquid two-phase flow with a small particle diameter. [ABSTRACT FROM AUTHOR]

The factor dominating olefin to paraffin ratio in cobalt-catalyzed Fischer-Tropsch synthesis has been identified via experimental kinetic studies and theoretical calculations including the van der Waals interaction between the adsorbates and Co surfaces. The olefin to paraffin ratio for each carbon number is expressed as a function of adsorption energies of olefin and activation energies of hydrogenation steps. Density functional theory calculations on Co (0 0 0 1) surface were performed to provide a comprehensive fundamental insight for the chemistry governing the olefin to paraffin ratio. The calculated olefin to paraffin ratio decreases with chain length except for ethylene, which agrees well with the experimental results. The differences introduced to the adsorption energies of olefin by van der Waals functional are correlated with d-band center changes of the Co surface. The carbon number dependent adsorption energies of olefin, rather than the activation energies of their hydrogenation reactions, are the driven force for the carbon number dependent olefin to paraffin ratio. The insights may delineate a new blueprint for the rational design of catalysts with enhanced olefin to paraffin ratio. [ABSTRACT FROM AUTHOR]

Brown sugar contains large amount of taste-active compounds. However, the effect of lime water and temperature on brown sugar processing has not been systematically studied. Herein, the NMR and e-tongue were used to analyze the taste-active compounds and taste characteristics of sugarcane juice, syrup and brown sugar. The results showed that during the clarification stage, lime water decreased phenolic acids with simple structure, but increased sugars and umami amino acids, thus increasing the sweetness and umami of sugarcane juice. However, during the evaporation stage, both lime water and high-temperature heating accelerated the Maillard reaction and caramelization of the syrup. During the concentration stage, temperature had the greatest influence on the taste in the processing of brown sugar. Under vacuum heating, it could retain more sugars, amino acids, organic acids and phenols, thus increasing sweetness and umami; meanwhile, it could reduce color, thus reducing bitterness and astringency. These data indicate that the taste-active compounds and taste characteristics of brown sugar can be improved by membrane filtration (without lime water) and vacuum heating. • In brown sugar processing, samples were obtained by changing lime water and heating. • Sweetness is the main taste of the six tastes detected by the e-tongue. • NMR showed vacuum heating significantly increased the taste-active compounds in brown sugar. • Lime water and high-temperature heating accelerated the Maillard reaction and caramelization. • Membrane filtration and vacuum heating can be applied to rich the taste of brown sugar. [ABSTRACT FROM AUTHOR]

Deep-fat fried battered and breaded foods are worldwide popular foods. In this study, egg yolk phospholipids, as well as alanine and glucose were used to generate the key odorants of fried coatings. The volatile compounds of fried coatings were extracted and analyzed by HS-SPME-GC-MS, and aroma profiles were analyzed via quantitative descriptive analysis. The results showed that the characteristic deep-fat frying odorants derived from Maillard reaction and lipids, such as methional, 2-methylbutanal and 3-methylbutanal, 2-ethyl-3,5-dimethylpyrazine, 2,4-decadienals, etc. were the highest amounts in the phospholipids & alanine and glucose treated sample, whereas the lowest in the control sample. Meanwhile, the aroma attributes had the same tendency as those of the odorants. The results proved that egg yolk phospholipids combined with alanine and glucose could be used to generate the key odorants of fried battered and breaded foods and enrich the volatile profile with a variety of Maillard reaction odorants. This treatment has a great potential use in catering industry. • Phospholipids could produce the characteristic lipid-derived odorants. • Alanine and glucose treatment could generate the typical Maillard reaction odorants. • Phospholipids combined with alanine and glucose produced key odorants simultaneously. • The aroma attributes by sensory study confirmed the rising trend of the key odorants. • Phospholipids combined with alanine and glucose is potential in deep-fat frying. [ABSTRACT FROM AUTHOR]

Au/TS-1 catalyst prepared by deposition–precipitation method is efficient for propene epoxidation with H 2 /O 2 , and its performance is significantly affected by the preparation parameters and the properties of support. In this work, effects of the slurry aging time and Si/Ti ratio of support on the location of Au nanoparticles inside or outside the micropores of TS-1 supports are examined by multi-techniques such as in situ characterization and molecular dynamics simulation, and the as-obtained catalysts are tested for propene epoxidation. It is found that longer slurry aging time facilitates the evolution of Au complex into smaller sized species which is easier to locate inside the micropores. Accordingly, the as-reduced catalyst has more tiny Au nanoparticles that are extremely active inside micropores and shows higher initial PO formation rate (g PO h −1 g Au −1 ). In addition, high Si/Ti ratio of TS-1 also favors the deposition of Au nanoparticles inside micropores, resulting in higher initial activity but lower stable activity. [ABSTRACT FROM AUTHOR]

Cream is usually used during baking and contributes a pleasant aroma to the baked foods, but the effect of its polar components on the cream flavor is not fully understood. In this study, the polar components were extracted by using ethanol, and then were analyzed by 1H nuclear magnetic resonance (NMR). The main compositions in the extraction were lactose, phospholipids, free amino acids and free fatty acids. Then all the samples were baked at 160 °C for 30 min , respectively. GC-MS analysis showed that the polar components could generate lots of odorants, and with the addition of polar components, the lipid-derived volatile compounds in cream were significantly increased and varied, as well as Maillard reaction and caramelization products, especially butanoic acid, hexanal, (E,E)-2,4-decadienal, furfural, furaneol, maltol, methylpyrazine, 2,3-dimethylpyrazine, 2-methyl and 3-methylbutanal. On the contrary, the ethanol-treated cream sample had less odorants. Sensory analysis confirmed that the caramel and roasted notes were significantly enhanced with the addition of polar components, the ethanol-treated cream and polar components sample was similar to the cream in the attributes of milk, sweet and buttery. These data indicated that polar components in cream could be used as a functional flavor enhancer. [Display omitted] • Volatiles in heated cream were extracted and analyzed by HS-SPME-GC-MS. • Polar components extracted by ethanol were analyzed by NMR. • Polar components promote lipid oxidation, Maillard reaction and caramelization. • Polar components enhanced the 'caramel' and 'roasted' flavor of heated cream. • Polar components could be of potential use to improve the baking flavor of foods. [ABSTRACT FROM AUTHOR]

Highlights: [•] CO hydrogenation studied at methanation conditions, 483K, 1.85bar, H2/CO=3–10. [•] Integrated transient and steady-state modeling as a powerful tool for useful kinetic parameters. [•] Combining experiments and DFT investigations of kinetic isotopic effect. [•] Dominating CO activation pathway through hydrogen-assisted CO dissociation. [•] Two carbon pools and two corresponding reaction pathways for CH4 formation. [ABSTRACT FROM AUTHOR]

Abstract: Dehydrogenation of propane (DHP) was studied over a series of xCr–SBA-15 and xCr–Al2O3 catalysts, prepared by incipient wetness impregnation, to gain a better understanding of the nature and distribution of Cr species and their catalytic function. To this end, the catalysts were characterized by N2-physisorption, X-ray diffraction (XRD), UV-Raman spectroscopy, scanning transmission electron microscopy–energy dispersive X-ray spectroscopy (STEM–EDXS) and X-ray absorption spectroscopy (XANES and EXAFS). All these characterization techniques indicate that, at ⩽1 wt% Cr, SBA-15 contains exclusively uniform distribution of chromium as isolated Cr(VI) species in tetrahedral () coordination, whilst on γ-Al2O3 a fraction of oligomers (including dimers) is present along with isolated species. At ⩾5 wt% Cr, SBA-15 is dominated by crystalline α-Cr2O3 particles, besides a fraction of isolated Cr(VI) species in coordination. Remarkably, γ-Al2O3 contains mainly oligomers with different degrees of nuclearity and a fraction of isolated species but no Cr2O3 particles. Among xCr–SBA-15 catalysts, those containing exclusively isolated Cr species (i.e., ⩽1 wt% Cr) exhibit higher activity and selectivity with respect to per mole of Cr than the catalyst dominated by crystalline α-Cr2O3 particles (⩾5 wt% Cr). The intrinsic activity of these isolated Cr species is higher than those observed on γ-Al2O3 (⩽1 wt% Cr). Interestingly, among xCr–Al2O3, the catalysts dominated by oligomeric species show the highest activity, indicating the important role of the species in the reaction. In situ XAS studies evidence that active Cr sites are apparently generated on-site during the reaction and that Cr is typically in (III) oxidation state. Based on ex situ and in situ characterization results and catalytic data, it appears that the activity of the Cr species is different in xCr–SBA-15 and xCr–Al2O3. For xCr–SBA-15, isolated Cr(III) sites with coordination number greater than four are more active, selective and stable than Cr sites on the surface of crystalline Cr2O3. In contrast, for xCr–Al2O3, oligomeric Cr species are more active and selective than the isolated Cr sites. [Copyright &y& Elsevier]