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Graph convolutional network (GCN) has been extensively applied to recommender systems (RS) and achieved significant performance improvements through iteratively aggregating high-order neighbors to model the relevance between users and items as well as their characteristics. In the aggregation process, GCN models usually give neighbors the same or trainable weights based on implicit features, ignoring explicit ones. In this work, we take the features with explicit meanings or extracted with specific purpose as explicit ones (e.g., temporal features) and the others contained in user-item network as implicit ones (e.g., user preferences). However, some explicit features and knowledge play an essential role in improving the model representation ability and explainability in recommendation systems. To deal with the limitation, we propose a GCN based framework to embed the explicit features or those extracted with explicit intentions in this work. We also provide specific implementations based on two commonly researched features, temporal evolution and popularity bias. Specifically, we first experimentally analyze the popularity bias of the representation learning in RS based on two commonly used GCN models. Secondly, we propose a general framework to weigh neighbors based on explicit features or intentions. Thirdly, we implement a Temporal and Popularity weighted Aggregator (TPA) for GCN. The Interest-Forgetting Curve is utilized to capture temporal evolution as temporal weights and the data-driven Beta distribution is employed to tune the weights based on the node popularity flexibly. At last, we conduct extensive experiments on three real-world datasets to demonstrate the effectiveness of TPA in improving recommendation accuracy and alleviating the popularity bias.

Alzheimer's disease (AD) is a degenerative disease of the central nervous system. The pathogenesis is still not fully clear. One of the main histopathological manifestations is senile plaques formed by β-amyloid (Aβ) accumulation. Aβ is generated from the sequential proteolysis of amyloid precursor protein (APP) by β-secretase [i.e. β-site APP cleaving enzyme 1 (BACE1)] and γ-secretase, with a rate-limiting step controlled by BACE1 activity. Therefore, inhibiting BACE1 activity has become a potential therapeutic strategy for AD. The development of reliable detection methods for BACE1 activity plays an important role in early diagnosis of AD and evaluation of the therapeutic effect of new drugs for AD. This article has reviewed the recent advances in BACE1 activity detection techniques. The challenges of applying these analysis techniques to early clinical diagnosis of AD and development trends of the detection techniques have been prospected.

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft X-ray regime. We used the tri-cellulose acetate (C$_{9}$H$_{16}$O$_{8}$) foam of 2 mg/cm$^{-3}$ density, and $1$-mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. The plasma parameters were diagnosed to be T$_{e}$=17 eV and n$_{e}$=4 $\times$ 10$^{20}$ cm$^{-3}$. The average charge states passing through the plasma were observed to be higher than those predicted by the commonly-used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. In previsous measurement with partially ionized plasma from gas discharge and z-pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we were able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-Glass laser radiation. The finding is important for heavy ion beam driven high energy density physics and fast ignitions., Comment: 7 pages, 4 figures, 35 conferences

Nowadays, oil pollution of water caused by illegal discharges or accidental events occurs frequently, and the waste of resources and environmental pollution cannot be ignored, so effective oil-water separation methods are needed to cope with such incidents. To solve these problems, this paper investigated an aerogel made from a plant polysaccharide, konjac glucomannan (KGM), supplemented with graphene oxide (GO), to improve the mechanical properties. Finally, a hydrophobic layer was attached to the surface and interior of the aerogel via chemical vapor deposition to improve its selectivity toward oil. Through a series of characterization methods such as infrared, X-ray photoelectron spectroscopy, and X-ray diffraction, it was demonstrated that KGM and GO were successfully cross-linked, resulting in excellent mechanical properties and directional absorption properties on oil. This composite polysaccharide aerogel could absorb oil 48 times its own weight. In addition, due to its strong mechanical properties, the gel can be reused many times, and the maximum recovery rate can be maintained at 96% after 10 cycles. Furthermore, the absorption of oil from water was conducted in a continuous mode, demonstrating the diversity of application scenarios. Generally, the results observed in this work have shown that the KGM aerogels have great potential for applications in oil-water separation.

The CaCO3 coated corundum aggregates were prepared by impregnating tabular corundum aggregates with sizes of 1–5 mm in calcium hydrogen citrate solution and heat treatment at 430 °C, which were also used in Al2O3–MgO castables. The effects of Ca2+/Cit3− mole ratio in precursor solution on coating characteristics of CaCO3 coated corundum aggregates as well as the effects of CaCO3 coatings on properties and microstructure of castables were investigated. It is found that the thickness and continuity of CaCO3 coating is increased and the size of CaCO3 particles in coatings decreases first and then increases as Ca2+/Cit3− mole ratio is decreased. High-temperature properties of castables are improved by in-situ formation of calcium hexaaluminate (CA6) layer at aggregate/matrix interface after sintering at 1600 °C. The Al2O3–MgO castables exhibit the best thermal shock resistance when Ca2+/Cit3− mole ratio is 1/3. It is contributed by deflections of cracks and consumptions of fracture energy in a continuous platelet CA6 layer with thickness of 10 μm, which is in-situ formed through reaction between Al2O3 and CaO derived from CaCO3 coatings. The present investigation provides a novel approach to enhance thermal shock resistance of the Al2O3–MgO castables.

The effects of three antioxidants (AlB2–Al–Al2O3 composite powders and Al and Al/Si composite powders) on the oxidation resistance of low-carbon magnesia-carbon refractories were investigated. First, thermodynamic calculations were performed to analyze the product compositions of the oxidized zone of low-carbon magnesia-carbon refractories with three antioxidants. Then, the oxidation zones were analyzed by X-ray diffraction, field emission scanning electron microscopy and energy spectrum analysis. The results show that the thickness of the decarburization layer of low-carbon magnesia-carbon bricks with Al powder, Al/Si composite powders and AlB2–Al–Al2O3 composite powders is 28.33 mm, 25.34 mm and 12.00 mm, respectively, which implies that the AlB2–Al–Al2O3 composite powder was the most effective antioxidant. The reason is that the Mg3B2O6 phase is formed in the products of the oxidation zone, and its melting point is 1360 °C. Therefore, it melts at 1400 °C and shows excellent oxidation resistance by filling the pores and blocking the oxygen channel. The products of the oxidation zone with Al and Al/Si composite powders were MgAl2O4 and Mg2SiO4 with high melting points, and that of the oxidation zone with Al powder was MgAl2O4. These products are still solid particles at 1400 C. The oxygen channel has a weaker blocking effect than the melt, so the oxidation resistance of Al/Si composite powders and Al powders is weaker.

SiC/Al2O3 composite powders with SiC nanowires were synthesized using a one-step combustion synthesis method taking silica fume (SiO2), aluminum powder (Al) and carbon black (CB) as raw materials, while ferrocene (C10H10Fe) was used as the catalyst. The calculated results for the relationship between the equilibrium phase and temperature of the Al–SiO2–C system show that SiC and Al2O3 are the only equilibrium phases in the system. In addition, the effects of C10H10Fe on the combustion synthesis process and products were studied. It was found that with increasing catalyst content, the amount of residual Si in the products first decreases and then increases, the combustion temperature first increases and then decreases, and the nanowire content continues to increase. For an optimal amount of C10H10Fe of 0.75 wt%, almost no residual Si is observed in the product, while the combustion temperature (Tc) is high (2104 K), the SiC nanowire content is relatively high, and the nanowire aspect ratio is large. In addition, two growth mechanism models for SiC nanowires: VS and VLS were validated.

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a polarization of $\sim$80%) and protons (with a polarization of $\sim$70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2-3) $\times$ 10$^{33}$ cm$^{-2}$ s$^{-1}$. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC. The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies. This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China., EicC white paper, written by the whole EicC working group

The key characteristics of the porous carbon materials and ceramic composites derived from citrates are directly affected by the pyrolysis mechanism of parent citrates and the microstructural revolution during the process. The pyrolysis mechanism of magnesium citrate nonahydrate (MCN) and the microstructural evolution during its pyrolysis were investigated by analysing the C/MgO nanocomposite powders from MCN pyrolyzed in carbon embedded condition and flowing argon atmosphere. The pyrolysis process of MCN was composed of the following stages: (1) MCN dehydrated to magnesium citrate at about 150 °C; (2) magnesium citrate decomposed into itaconic acid magnesium and MgO at about 300 °C; (3) itaconic acid magnesium decomposed into carbon, MgO and CH4 at around 500 °C; (4) CH4 was pyrolyzed and graphene was deposited on MgO. The carbon produced in stage (3) was turbostratic while that derived from the pyrolysis-deposition of CH4 was few-layered-graphene. The MgO nano grains produced in stage (2) precipitated and agglomerated while those derived from itaconic acid magnesium were much smaller in size. In carbon embedded condition, the few-layered-graphene not only deposited on the MgO aggregates surface but also inserted into the MgO nano grain boundaries, which suppressed the growth and sintering of MgO nano grains.

Our previous investigations indicate that the thermal shock resistance (TSR) of hydratable magnesium carboxylate (HMC) bonded Al2O3–MgO castables is superior to castables bonded with calcium aluminate cement as a result of the in-situ formation of micro-sized spinel (MgAl2O4). In the present study, to further enhance the TSR of HMC bonded castables, the submicron alumina powders were added into the castables to decrease the size of the spinel particle through a reaction of submicron alumina with nano magnesia pyrolyzed from HMC. The effects of submicron alumina powders on the TSR, slag corrosion resistance, and microstructure of HMC bonded castables were investigated. The results show that the size of the in-situ spinel particle decreases from approximately 2 μm to approximately 0.8 μm and the spinel gradually transforms into the aluminum-rich spinel after adding submicron alumina powders. The residual strength retention ratio of the samples raises from 37.5% to 50.0%, and the thermal stress damage resistance index (R՛՛՛՛) of the samples increases from 3.1 m to 7.2 m with the increase in the amount of submicron alumina to 2.0 wt% after thermal shock. The microcracks in the castables matrix of sample 2A are more and shorter than those of sample 0A after thermal shock. This is attributed to the fact that the resistance of microcracks propagation in the castables is enhanced via smaller spinel with uniform distribution. Besides, the penetration index of the castables decreases from 20.8% to 9.8% with the increase of submicron alumina content powders to 2.0 wt%. This is because the submicron alumina powders decrease the porosity of the castables, and the smaller size of the aluminum-rich spinel has a stronger adsorption capacity for Fe2+ ions.

With the Internet of Things (IoT) gradually showing a trend of socialization, the community structure has been widely used in IoT applications, such as the smart home and smart city. Therefore, using the IoT and data mining technology to detect and analyze the relevant communities in the network is worth studying. In this article, we aim to identify the $r$ most influential communities in a network, where an influential community is a cohesive subgraph with a considerable level of influence. In the literature, several efficient methods have been proposed to address this problem. These methods are all devised based on the assumption that nodes in the network are associated with different weights; in other words, every pair of nodes cannot have the same weight. Otherwise, these methods may retrieve imprecise results. However, nodes in a network may inevitably have the same weight in lots of real-world scenarios, such as mobile-edge computing networks. In this article, we are motivated to efficiently compute the top- $r$ influential communities in a general case where nodes in the network may have arbitrary weights. To this end, we first proposed a unified search framework by improving the existing techniques. Then, we developed an efficient algorithm to judge the connectivity of nodes with the same weight, whose time complexity is linear to the size of the subgraph accessed by the algorithm. We conducted extensive performance studies on real data sets to demonstrate the effectiveness and efficiency of the proposed approaches.

The Al–Al2O3 composites were prepared by fused alumina, α-Al2O3 micropowders, and metal aluminum powder. The samples with 3% carbon black (N330), 3% resin powder and α-Al2O3 micropowder, 10% α-Al2O3 micropowder were named S1, S2, and S3, respectively. They were oxidized at 1500 °C for 3 h in a box-type electric furnace, and then the unoxidized areas were analyzed by X-ray diffraction and scanning electron microscopy. It was found that the aluminum oxycarbonitride formed in situ during the oxidation resistance test inhibited further oxidation of S2. The in situ formation mechanism of aluminum oxycarbonitride in the unoxidized zone is believed to be 7Al + 3Al3C4 + 12AlN + 4Al2O3 = 12Al3CON, which is also verified and proven by XRD, SEM and EDS in this work. The oxidation depth of S2 is 46.7% lower than that of S3. Sample S2 hardly has any linear change after fired at 1500 °C × 3 h in coke, which benefits to improve the volume stability and prolongs the service life. Among the three batches, S2 exhibits the minimum creep rate, from 0% to 0.026% at 1500 °C, and the HMOR at 1500 °C in a N2 atmosphere of S2 is 58 MPa. The Al–Al2O3 composites combined with resin strengthened by in situ formed aluminum oxycarbonitride give the composites excellent high-temperature strength owing to the fiber-intersected reinforced microstructure of Al3CON crystals at high temperature. In the Al–C–N–O system, it was found that the general formula of aluminum oxycarbonitride is expressed by Al4n+m(C,O,N)3n+m, and the (n, m) values are (0, 3) for Al3CON.

Hydratable magnesium carboxylate (HMC), which is similar to the properties of cement, can be used as a potential binder for refractory castables. However, its decomposition may lead to poor mechanical properties at medium temperatures (300 °C–1100 °C). This work investigated the effects of boric acid on the mechanical properties and microstructural evolution of castables bonded with hydratable magnesium carboxylate. The mechanical strength, bulk density, apparent porosity, thermal shock resistance, and sintering properties of the castables were evaluated. The results showed that the mechanical properties of HMC-bonded castables (HMCC) at various temperatures can be improved by adding boric acid. Boric acid reacts with HMC to form magnesium carboxylate borate ester (MCBE), which improves the bonding strength between HMC molecules. Thus, the cold modulus of rupture of HMCC containing boric acid dried at 110 °C are higher than that of calcium aluminate cement-bonded refractory castables (CACC). The decomposition temperature of MCBE is 77 °C higher than that of HMC, so MCBE can endow castables with better mechanical properties at 110 °C–500 °C. The B4C obtained by MCBE pyrolysis could form a boron-rich liquid phase, which can accelerate the structural densification of castables via transient liquid phase sintering, thus improving the mechanical properties of castables at 500 °C–1100 °C. Moreover, boric acid can improve the thermal shock resistance of HMCC. The residual strength rate first increases and then decreases with an increasing boric acid, and reaches a maximum value of 29.7% (1 wt% boric acid is added), which is 2.3 times that of the CACC. The nanoindentation test showed that the microcracks in the matrix of 1 wt% boric acid castables are easy to initiate but difficult to propagate, so the microcracks are many and wavy.

A novel electromagnetic wave (EMW) absorber was prepared by combustion synthesis. Boron carbide (B4C) powders with different grain sizes using a molten-salt-assisted combustion technique with B2O3, CB (carbon black), and Mg powders as starting materials, and NaCl as an additives. The effects of the NaCl content on the phase compositions and the microstructure of the products were characterized. A combustion front quenching method was used to elucidate the mechanism for the B4C powders synthesis. The dielectric, and EMW absorbing properties in the X-band were also investigated. The results showed that the addition of NaCl significantly reduced the grain size of B4C powders. Nanoscale B4C powders with cubic polyhedral structures were synthesized using 6 wt% NaCl (labeled as N-6). According to the quenching test results can be obtained that the first step in the combustion synthesis was melting B2O3 into a glassy substance. At the same time, Mg melted and formed a liquid pool into which the NaCl dissolved, followed reduction of the B2O3 to B. The formed B eventually reacted with CB to form B4C, and the B4C particles precipitated from the matrices. The N-6 sample exhibits optimal dielectric and EMW absorbing properties, because of a high specific surface area that enhances interfacial and space charge polarization.

The addition of C/MgAl2O4 composite powders can improve the thermal shock resistance of low-carbon Al2O3–C refractories attribute to the formation of microcracks in the agglomerated structure, thus consuming more thermal stress and strain energy. Moreover, C/MgAl2O4 composite powders additive promote the formation of short fibrous ceramic phases in the refractories, which suggest a bridging role in the interior of the refractories and increase its toughness. Furthermore, the C/MgAl2O4 composite powders also result in a remarkable enhancement of the slag corrosion resistance in the refractories.

In-situ 2D nanocarbon/calcium aluminate composite (NCAC) was synthesized via a combustion method designed based on aluminothermic reduction using calcium carbonate (CaCO3) as carbon source. The results demonstrate that compared with the pristine product, when the molar substitution rate of CaCO3 for CaO2 in the reactants was 25%, the contents of CaAl2O4 (CA), CaAl4O7 (CA2) and Ca12Al14O33 (C12A7) in the combusted product did not change substantially and were close to those of Secar71. When the molar substitution rate was increased to 50%, the contents of CA and CA2 decreased, and that of C12A7 increased substantially. Interestingly, the nanocarbons generated in-situ in the combusted composite were embedded in calcium aluminate and had a nanoflake morphology (2D) with a thickness of approximately 50 nm, few defects and high graphitization degree. The results of the suspension experiment demonstrate that the floating ratio of NCAC in the suspension after ultrasonic vibration for 10 min was approximately 5.5 wt.%, which is much lower than that (78.8 wt.%) of a carbon black/Secar71 composite powder; thus, the in-situ 2D nanocarbon/aluminate composite had strengthened interfacial bonds and satisfactory separation resistance. These would be favorable for the uniform dispersion of nanocarbons within the matrix, improving the performance of cement-based composites.

Mg K-shell x-ray production cross sections have been investigated for the impact of H+, He2+ and highly charged heavy ions Xe20+ and Eu20+ in the energy range near the Bohr velocity. The x-ray production cross sections were extracted from the yield and compared with various theoretical calculations. It is found that, with the same incident energy per nucleon, the cross section induced by light ions is lower than that produced by highly charged heavy ions by a factor of about 104. With the impact of H+ and He2+ ions, the x-ray emission cross section can be well predicted by ECPSSR theory. However, for the bombardment of highly charged heavy ions, the BEA calculation, corrected both by Coulomb repulsion and effective nuclear charge, results in a good estimation to the experimental data.

C/MgO composite powders were prepared by combustion synthesis using magnesium oxalate and magnesium powders as raw materials. The phase composition and microstructure of the composite powders were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy/energy dispersive spectroscopy (FESEM/EDS), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. The synthetic mechanism was explored through TG-FTIR and combustion front quenching techniques. It was found that the C/MgO composite powders contained a large quantity of MgO nanofibers. When the molar ratio of magnesium oxalate and magnesium was 1:4, the carbon content of the product reached a maximum of 9.45 wt %. In the composite powders, cubic MgO particles were encapsulated by a thin carbon layer, and there was a tiny gap between MgO and the carbon layer; a large number of MgO nanofibers with aspect ratios of 80–100 were found. The cubic MgO particles of the products are the direct decomposition of MgC2O4, and the MgO nanofibers are the reaction product of gaseous Mg and CO2/CO at high temperature. Meanwhile, the carbon deposited on the MgO particles can inhibit the grain growth of MgO particles and result in the refinement of MgO particles. The uniform dispersion of carbon and the weak C/MgO interface combine, making the composite powders a potential additive for low-carbon MgO–C refractories with excellent thermal shock resistance.