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To solve the pollution problems that result from polypropylene (PP), suitable biopolymers such as poly (lactic acid) (PLA) were selected to blend with PP. Since PP/PLA blends are often exposed to the natural environment, it is necessary to study the photodegradation behavior of PP/PLA blends. In this paper, PP/PLA blends with different compositions were prepared by extrusion and subjected to the accelerated laboratory weathering equipment. The effects of compatibilizers on the degradation behavior of PP/PLA blends were also studied. The weatherability of PP/PLA blends was studied through weight loss, optical microscope, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results revealed that PP is easy to degrade than PLA during accelerated laboratory weathering. PP/PLA blends are susceptible to the accelerated laboratory weathering process, and PP-rich and PLA-rich blends reduce the weathering resistance. Moreover, the results indicate that the initial degradation temperature, melting temperature, and crystallization temperature decrease after weathering related to the decreased thermal stability of PP/PLA blends. For instance, the initial degradation temperature of PP/PLA8.2 reduces from 332.2 °C to 320.2 °C. Moreover, the compatibilized sample is generally more resistant to weathering conditions than the uncompatibilized one due to the higher compatibility of PP and PLA. [ABSTRACT FROM AUTHOR]

The single-crystal structures of imine-thioethanediyl-bridged [OSNO]-type bis(phenolato) titanium dichloro complexes were first characterized. Upon activation with appropriate aluminum compound cocatalysts, the resultant titanium complexes were moderately active towards syndiospecific styrene polymerization. Resonance signals of titanium (III) have been detected in catalytic systems of syndiospecific styrene polymerization by electron paramagnetic resonance, proving the actual active species was cationic titanium (III) complexes. Next, using the cationic titanium complexes [OSNO]Ti+-CH3 hypothetically as active species for exemplifying the initiation step of polymerization of styrene, density functional theory studies related to styrene insertion have been performed on two model molecules. In both cases, the pathway of 2, 1-insertion of styrene came out to be more favorable thermodynamically and kinetically. Moreover, the spacial repulsions among the bulky phenolato groups and the phenyl group of the incoming styrene are believed to be controlling the complexes' reactivity. [ABSTRACT FROM AUTHOR]

The parameter server architecture has shown promising performance advantages when handling deep learning (DL) applications. One crucial issue in this regard is the presence of stragglers, which significantly retards DL training progress. Previous solutions for solving stragglers may not fully exploit the computation resource of the cluster as evidenced by our experiments, especially in the heterogeneous environment. This motivates us to design a heterogeneity-aware parameter server paradigm that addresses stragglers and accelerates DL training from the perspective of computation parallelism. We introduce a novel methodology named straggler projection to give a comprehensive inspection of stragglers and reveal practical guidelines to solve this problem in two aspects: (1) controlling each worker's training speed via elastic training parallelism control and (2) transferring blocked tasks from stragglers to pioneers to fully utilize the computation resource. Following these guidelines, we propose the abstraction of parallelism as an infrastructure and design the Elastic-Parallelism Synchronous Parallel (EPSP) algorithm to handle distributed training and parameter synchronization, supporting both enforced- and slack-synchronization schemes. The whole idea has been implemented into a prototype called Falcon which effectively accelerates the DL training speed with the presence of stragglers. Evaluation under various benchmarks with baseline comparison demonstrates the superiority of our system. Specifically, Falcon reduces the training convergence time, by up to 61.83, 55.19, 38.92, and 23.68 percent shorter than FlexRR, Sync-opt, ConSGD, and DynSGD, respectively. [ABSTRACT FROM AUTHOR]

Big data analytics in datacenters often involve scheduling of data-parallel jobs. Traditional scheduling techniques based on improving network resource utilization are subject to limited bandwidth in datacenter networks. To alleviate the shortage of bandwidth, some cluster frameworks employ techniques of traffic compression to reduce transmission consumption. However, they tackle scheduling in a coarse-grained manner at task level and do not perform well in terms of flow-level metrics due to high complexity. Fortunately, the abstraction of coflow pioneers a new perspective to facilitate scheduling efficiency. In this paper, we introduce a coflow compression mechanism to minimize the completion time in data-intensive applications. Due to the NP-hardness, we propose a heuristic algorithm called Fastest-Volume-Disposal-First (FVDF) to solve this problem. For online applicability, FVDF supports stage pipelining to accelerate scheduling and exploits recurrent neural networks (RNNs) to predict compression speed. Meanwhile, we build ${\sf Swallow}$ Swallow , an efficient scheduling system that implements our proposed algorithms. It minimizes coflow completion time (CCT) while guaranteeing resource conservation and starvation freedom. The results of both trace-driven simulations and real experiments show the superiority of our algorithm, over existing one. Specifically, ${\sf Swallow}$ Swallow speeds up CCT and job completion time (JCT) by up to $1.47 \times$ 1. 47 × and $1.66 \times$ 1. 66 × on average, respectively, over the SEBF in Varys, one of the most efficient coflow scheduling algorithms so far. Moreover, with coflow compression, ${\sf Swallow}$ Swallow reduces data traffic by up to 48.41 percent on average. [ABSTRACT FROM AUTHOR]

Among the vinyl chloride production processes, ethane oxychlorination is the most economical and environment-friendly process but constrained by the lack of high performance catalysts for industrial applications. In this work, FeCl3–KCl/Al2O3 catalysts with different molar ratios of K/Fe were prepared by a co-impregnation method and applied to ethane oxychlorination. The FeCl3–KCl/Al2O3 catalyst with K/Fe = 2 exhibited enhanced catalytic performance with the highest conversion of C2H6 (99.1%) and the best selectivity to C2H3Cl (74%) under the optimal conditions of 400 °C, C2H6 : HCl : air = 1 : 3 : 5.5 (volume ratio) and GHSV = 4560 h−1. It was found that the enhanced catalytic performance could be attributed to the formation of KFeCl4 from KCl and FeCl3 and the change of the reaction process. Besides, KCl is in favor of weakening the interaction between the active species and support. The reduction activation energy of Fe(iii) → Fe(ii) is efficiently reduced by KCl addition. The FeCl3–KCl/Al2O3 catalyst may be a potential catalyst for industry due to its simple composition and convenient preparation. [ABSTRACT FROM AUTHOR]

Molybdenum diselenide (MoSe 2) have attracted much attention as an anode material for lithium/sodium ion batteries due to its specific layered structure. Here, highly-uniform MoSe 2 nanoparticles are successfully synthesized via a one-pot hydrothermal method with addition of polyvinyl pyrrolidone (PVP) following by calcination treatment. PVP serves as a surfactant preventing the over-agglomeration of MoSe 2 nanosheets and contributing to the well-organized accumulation of MoSe 2 nanosheets into nanoparticles. When evaluated as anode for lithium ion batteries, the MoSe 2 nanoparticles show enhanced cycle stability and rate performance comparing to the MoSe 2 bulk prepared without addition of PVP. After 200 cycles, the MoSe 2 nanoparticles remain a specific capacity of 573.9 mAh g−1 at a rate of 200 mA g−1. Meanwhile, MoSe 2 nanoparticles also display good sodium storage performance. Under the current density of 500 mA g−1, MoSe 2 nanoparticles exhibit reversible capacity of 374.9 mA h g−1 after 100 cycles. [Display omitted] • Highly-uniform MoSe2 nanoparticles are successfully synthesized via a simple method. • The effect of PVP during the particle formation has been studied in detail. • The as-prepared MoSe2 nanoparticles show enhanced electrochemical performance as anode materials. [ABSTRACT FROM AUTHOR]

Two C 1 -symmetric [OSNO]-type ethanediyl-bridged imine-thiobis(phenolate) titanium (IV) complexes of [Ti(OC 6 H 2 -6- t Bu-4- t Bu) 2 {CH N(CH 2 ) 2 SCH 2 }Cl 2 ] and [Ti(OC 6 H 2 -6- t Bu-4- t Bu) 2 {CH N(CH 2 ) 2 S}Cl 2 ] were synthesized by reacting the corresponding ethanediyl-bridged imine-thiobis(phenols) [(HOC 6 H 2 -6- t Bu-4- t Bu) 2 {CH N(CH 2 ) 2 SCH 2 }] and [(HOC 6 H 2 -6- t Bu-4- t Bu) 2 {CH N(CH 2 ) 2 S}] with the titanium precursor TiCl 4 . The resultant complexes and intermediates were characterized by elemental analysis (EA) and nuclear magnetic resonance (NMR). Upon activation with triisobutyl aluminum modified methylalumoxane (MMAO), the [OSNO]-type titanium complexes can polymerize styrene into syndiotactic polystyrene ( s PS) with high syndiotacticity (rrr > 95%). Electron paramagnetic resonance (EPR) analysis on [OSNO]-type titanium (IV) complexes in the presence of MMAO in toluene revealed that cationic titanium (III) complexes are the active species for syndiospecific polymerization of styrene. Furthermore, it was found from the end group analysis of the polymerization products by NMR that the selective chain transfer to MMAO took place during syndiospecific polymerization of styrene. [ABSTRACT FROM AUTHOR]

We investigate the spin-3/2 baryons in the 27-plet based on flavor SU(3) symmetry. For J p = 3/2+, we find all the candidates for non-exotic members. For J p = 3/2-, we predict a new non-exotic member Λ(1780). Fitting the mass spectrum and calculating the widths of the members show an approximate symmetry of the 27-plet of SU(3). We find that the exotic members have relatively large widths and the Ξ(1950) has spin and parity J p = 3/2-. The possibility of assigning the non-exotic candidates to an octet is also analyzed. [ABSTRACT FROM AUTHOR]

A series of boron-modified low-gold-content Au-based catalysts were prepared by impregnation. Characterization by N 2 adsorption/desorption, XPS, H 2 –TPR, HCl/C 2 H 2 –TPD, TG, TEM, and SEM was applied to analyze the catalyst. Compared with the unmodified catalyst, B-modified Au0.25%/BAC-20% exhibited better performance (acetylene conversion increase by 21.4% and selectivity to VCM of more than 99.5%) at a space velocity of 770 h −1 and 150 °C. The results indicated that the presence of boron species is favorable to the stabilization of catalytically active Au 3+ species and the inhibition of Au 3+ to Au 0 during acetylene hydrochlorination, and hence improves the catalytic stability. In addition, the presence of boron species can effectively inhibit carbon deposition and also inhibit the catalyst sintering during the reaction. TPD experiments revealed that not the adsorption ability of C 2 H 2 but the adsorption ability of the HCl played a crucial role in boron-modified Au-based catalysts. [ABSTRACT FROM AUTHOR]

In the present study, polystyrene (PS) nanowires in aqueous dispersion with a diameter ranging from 120 to 300 nm are prepared via electrospun and dispersed in water. Relatively, PS nanowires confined in anodic aluminum oxide (AAO) template are prepared through drawing PS flow into the tube of AAO template. Scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) are used to characterize the size of the resultant nanowires and ensure the successful preparation of nanowires. Moreover, the glass transition and physical aging behaviors of the PS nanowires in aqueous dispersion and confined in AAO template are investigated by differential scanning calorimetry (DSC). The PS nanowires in aqueous dispersion and confined in AAO template exhibit different glass transition and physical aging behaviors. [ABSTRACT FROM AUTHOR]

Supported perovskite promoted catalysts La 2 NiMnO 6 –CuCl 2 /γ-Al 2 O 3 and La 1.7 K 0.3 NiMnO 6 –CuCl 2 /γ-Al 2 O 3 were prepared by mechanical mixing method, and characterized by XRD, H 2 -TPR, XRF, XPS and magnetization techniques. The catalyst doped with potassium La 1.7 K 0.3 NiMnO 6 –CuCl 2 /γ-Al 2 O 3 possesses a large amount of Mn 4+ and surface-adsorbed oxygen species, which accelerate the oxidation of Cu + by a circular reaction and increase the release of Cl 2 , and therefore promote the conversion of C 2 H 6 and the selectivity to C 2 H 3 Cl. The catalyst La 1.7 K 0.3 NiMnO 6 –CuCl 2 /γ-Al 2 O 3 shows better catalytic activity for ethane oxychlorination with the C 2 H 6 conversion of 100% and the C 2 H 3 Cl selectivity to 59.4%. The total selectivity to C 2 H 4 and C 2 H 3 Cl maintains over 81% in 95 h. This study points out a potential way to develop more active perovskite-type oxide catalysts for ethane oxychlorination. [ABSTRACT FROM AUTHOR]

Chromium-doped CuCl 2 –KCl–CeO 2 –Cr x /γ-Al 2 O 3 with different content (Cr 0, 1, 3, 5, 7 and 9 wt.%) were synthesized by co-impregnation method and characterized by XRD, BET, SEM, H 2 -TPR and XPS techniques. It is found that the addition of chromium species increases a large amount of capping oxygen species on the catalysts surface, reduces the reduction activation energy of Cu(II) → Cu(I) process efficiently, and accelerates the transition of redox group Cu(II)/Cu(I). Meanwhile, the addition of chromium species also affects the crystal size of CeO 2 on the surface. The best catalyst is CuKCeCr 3 with Cr (3 wt.%), which exhibited highest conversion of C 2 H 6 (97.8%) and best selectivity to C 2 H 3 Cl (68.2%). [ABSTRACT FROM AUTHOR]

As catalysts, metal nanoclusters (NCs) have become the focus of research due to their precise structure and excellent catalytic activity. In general, it can greatly improve the catalytic activity of NCs by thermal treatment. In this work, the ZnO supported 2,4-dimethylbenzenethiol-protected-[Ag 25 (C 8 H 9 S) 18 ]- NCs (Ag 25 @ZnO) nanocatalysts were subjected to activation temperatures of 100 °C, 200 °C and 300 °C to remove the surface ligands of Ag 25 NCs and regulate the surface composition of Ag 25 @ZnO nanocatalysts. The structure of Ag 25 @ZnO nanocatalysts were characterized by XRD, SEM, TEM, EDS and XPS. In particular, the XPS results obviously confirmed that the concentration of Ag+ on the catalyst surface was positively correlated with the activation temperature. Finally, the effect of the Ag + content on the catalytic activity of the Ag 25 @ZnO nanocatalysts was also explored. Because the content of Ag+ in Ag 25 @ZnO-300 nanocatalysts is the highest, the 4-nitrophenol reduction reaction showed the best catalytic performance. The ZnO supported [Ag 25 (SPhMe 2) 18 ]- NCs (Ag 25 @ZnO) catalysts was activated with thermal calcination approach at 100 °C,200 °C and 300 °C, and the catalytic performance for the reduction reaction of 4-nitrophenol exhibits a positive correlation with the concentration of Ag+, which also shows a positive correlation with activation temperatures. [Display omitted] • Ag 25 @ZnO catalysts was activated with thermal calcination approach. • The content of Ag + on Ag 25 @ZnO is correlated with the thermal temperature. • Due to the increase of Ag+, the Ag 25 @ZnO-300 shows the best catalytic performance. [ABSTRACT FROM AUTHOR]

• CuCr 2 O 4 Spinel is a potential catalyst for ethane oxychlorination. • The Mg2+ doped at the CuCr 2 O 4 A-site exhibites enhanced catalytic activity. • The addition of Mg2+ enhances the reduction ability of Cu (II) to Cu (I). • C 2 H 3 Cl is preferentially desorbed in the transformation of C 2 H 6 in the (1 2 1) plane. A series of novel spinel oxide catalysts, Cu 1− x Mg x Cr 2 O 4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1), for the ethane oxychlorination catalytic reaction were prepared by a sol–gel method, and X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller, H 2 temperature-programmed reduction, O 2 temperature-programmed desorption, and X-ray photoelectron spectroscopy were used to characterize the catalysts. It was found that the enhanced catalytic performance could be attributed to A-site doping of Mg2+ in the CuCr 2 O 4 catalysts. The addition of Mg2+ changes the preferred orientation of the crystal from CuCr 2 O 4 (0 2 0) to Cu 0.6 Mg 0.4 Cr 2 O 4 (1 2 1) and leads to lattice distortions and more surface defect oxygen species in Cu 0.6 Mg 0.4 Cr 2 O 4. The Cu 0.6 Mg 0.4 Cr 2 O 4 catalyst shows optical catalytic performance for ethane oxychlorination, with an average ethane conversion of 95.6% and a vinyl chloride selectivity of 50.2%. Density functional theory results showed that the Cu 0.6 Mg 0.4 Cr 2 O 4 catalyst would enhance the adsorption ability of the crystal (1 2 1) plane for C 2 H 6 , C 2 H 3 Cl, and C 2 H 4. C 2 H 3 Cl is preferentially desorbed in the conversion of reactant C 2 H 6 on the (1 2 1) plane. It is evident that the difference in electron density between C 2 H 3 Cl and C 2 H 4 on the planes contributes to the improvement of Cu 0.6 Mg 0.4 Cr 2 O 4 selectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal/N doped carbon composite is prepared by a melamine-assisted cellulose pyrolysis. • Metal/N doped carbon composite is magnetic and quickly separated from solution. • Magnetic composite has big mesopore volume and electron deficient conjugated surface. • Dye adsorption on magnetic composite is reached via electrostatic and π-π interaction. • Magnetic composite has a high adsorption capacity of Congo red, especially at high pH. A magnetic and mesoporous metal/N-doped carbon composite is prepared using a melamine-assisted pyrolysis method of hydroxypropyl methylcellulose with Fe(NO 3) 3. The magnetic composite has a 3D hierarchical structure composed of 1D nanostructure interlaced with each other and a large pore volume distributed mainly in mesopores. Meanwhile, its N-doped carbon surface with sp2 hybridized structure is positively charged due to the promotion action of its mixed Fe phase, Fe 3 C and Fe 3 N, inducing the production of electron deficient conjugated structures as electron acceptors. Its characteristic microstructure determines that the adsorption of anionic Congo red on its surface is achieved mainly through multiple adsorption mechanisms of electrostatic and π-π interaction. Thus, the magnetic composite has an excellent dye adsorption capacity, even improved dramatically at high pH conditions, and simultaneously, the spent composite is quickly separated from wastewater solution by using its magnetic properties. In contrast, these undoped or N-doped carbon composites prepared in the absence of melamine and Fe salts have very poor or partially improved adsorption efficiencies to the Congo red dyes due to their inactive characteristic microstructures, such as lower pore volume, more microporous structures and negatively charged mesoporous surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni doped Ce 2 O 3 @CeO 2 /CN composite is prepared in pyrolysis by tuning nickel doping. • CeO 2 surface is reduced in air to form Ce 2 O 3 @CeO 2 structure by carbon nitrides. • Carbon nitride structure is activated and positively charged by Ce 2 O 3 @CeO 2 structure. • Ni doped Ce 2 O 3 @CeO 2 /CN composite has highest adsorption capability of Congo red. Sheet-like Ni doped Ce 2 O 3 @CeO 2 /CN composite is synthesized by tuning the introduction of nickel in a facile and low-cost pyrolysis process. Due to the activation of the shell-core Ce 2 O 3 @CeO 2 structure, the nitrogen chemical state in the carbon nitrides is mainly in the form of an N-(C 3) structure, inducing the production of excellent electronic conductivity and positive charges on carbon nitrides. For the pyrolytic synthesis of the composite, the amount of nickel doping is a crucial factor. Under no nickel condition, only CeO 2 is synthesized and positively charged. With increasing nickel content, Ni doped CeO 2 /CN composite is prepared and negatively charged due to its main component of CeO 2 and the change of its carbon nitride structure. Ni doped CeO 2 prepared with high enough nickel content presents individual NiO particles and its negatively charged surface. The removal of these designed composites for anionic Congo red is utilized to reveal the significant influence of their surface structure. Ni doped Ce 2 O 3 @CeO 2 /CN composite depicts the highest removal performance. Ni doped CeO 2 /CN composite, despite the great change in its carbon nitride structure, still has much higher removal efficiency than pure CeO 2. However, Ni doped CeO 2 is found to have lower adsorption performance than pure CeO 2. [ABSTRACT FROM AUTHOR]