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The feature of “curing at low temperature, directly used in extreme conditions” made the adhesion technique more suitable for engineering application. The superalloy was successfully bonded at high temperatures by a multi-components modified, phenix-silicone-based adhesive, through forming various ceramics and intermetallics. The intermetallization process not only modified the thermal expansibility of adhesive, but also improved the compositional continuity and reaction extent around bonding interface. With the heating temperature increasing from 500 °C to 1000 °C, various high-temperature-resistant phases in turn generated in adhesive, and the chemical reactions on interfaces became more and more intense. Eventually, the room temperature shear strength of joints calcined at 700 °C reached the maximum value of 28.3 MPa, and the high temperature strength was still up to 18.4 MPa at 800 °C. Moreover, after 6 thermal cycles, the residual strength for joints calcined at 700 °C almost remained ∼13 MPa. The exclusive adhesive absolutely facilitated the repair and connection of engineering superalloy.

The growth of polycyclic aromatic hydrocarbons (PAH) can proceed via multiple chemical mechanisms. The mechanism of naphthyl radical and vinylacetylene (C4H4) addition reaction has been systematically investigated in this computational study. A combination of DFT/B3LYP/6-311+G(d,p), CCSD/6-311+G(d,p) and CBS-QB3 methods were performed to calculate the potential energy surfaces. It revealed that the products, including phenanthrene, anthracene, a PAH with a five-membered ring structure, and PAH with a C4H3 radical substitution, can be formed in A2-1 (1-naphthyl)+C4H4 and A2-2 (2-naphthyl) +C4H4 reaction networks. The reaction rate constants at 0.1-100 atm were evaluated by RRKM theory by solving the master equation in the temperature range of 800–2500 K, which showed that the rate constants of reactions A2-1 (A2-2)+C4H4→product+H are highly temperature-dependent but nearly pressure-independent. The distribution of products was investigated in a 0-D batch reactor, wherein the initial reactant concentrations were taken from experimental measurements. The results showed that adduct intermediates were the main products at low temperature (T 1000 K). It was observed that a significant amount of phenanthrene is formed from PAH with a C4H3 radical substitution with the assistance of H atom. Reaction pathway sensitivity analysis for the PAH radical+C4H4 reaction system was performed and showed that the new benzene rings are more likely to be generated near the zig-zag edge surface site instead of the free edge. For the development of a PAH mechanism, the analogous treatment of rate constants for larger PAH radical + C4H4 reaction system are discussed. The formation rate of naphthalene from the reaction of phenyl+C4H4 was found to be very close to that of phenanthrene from the reaction of naphthyl+C4H4, suggesting that the analogous treatment of the rates is reasonable in PAH mechanisms.

A k-rainbow dominating function (kRDF) of G is a function $$f:V(G)\rightarrow {\mathcal {P}}(\{1,2,\ldots ,k\})$$ for which $$f(v)=\emptyset $$ we have $$\bigcup \nolimits _{u\in N(v)}f(u)=\{1,2,\ldots ,k\}$$ . The weightw(f) of a function f is defined as $$w(f)=\sum _{v\in V(G)}\left| f(v)\right| $$ . The minimum weight of a kRDF of G is called the k-rainbow domination number of G, which is denoted by $$\gamma _{rk}(G)$$ . In this paper, we determine the exact values of the 2-rainbow domination numbers of $$C_4\Box C_n$$ and $$C_8\Box C_n$$ . It follows that $$\gamma _{r2}\not = 2\gamma $$ for graphs $$C_4\Box C_n$$ ( $$n \ge 4$$ ) and $$C_8\Box C_n$$ ( $$n \ge 8$$ ), answering in part a question raised by Bresar.

Acoustic mode investigation provides essential guidance in silent aero-engine designing by measuring pressure perturbations around the duct. Instead of mounting a full sensor array (FSA), compressive sampling (CS) feasibly achieves identical resolution with lower microphone requirement. In this paper, a generalized minimax-concave (GMC) regularized CS model is proposed as alternative to L1-norm regularized one for acoustic mode measurements, offering more accurate results by the use of fewer microphones. Improvement is guaranteed by the potential of GMC penalty due to sparsity inducing. Meanwhile the convexity of the cost function is also maintained via setting the scale matrix. It captures both advantages of nonconvex regularization and convex optimization. The effectiveness of the approach is validated on an aero-engine fan test rig. The tonal noise series are firstly separated from the sound pressure signals via cyclostationary analysis, thus amplitudes of tonal modes are estimated exactly. Two cases under different shaft speeds are conducted to estimate acoustic tonal modes, and results indicate that the proposed approach outperforms L1-norm regularized method in reconstruction accuracy. The effect of sensor number on reconstruction accuracy is also investigated, showing the proposed GMC method enables appropriate mode estimation from much fewer sensors.

In aviation and navigation, complicated parts are milled with high-speed low-feed-per-tooth milling to decrease tool vibration for high quality. Because the nonlinearity of the cutting force coefficient (CFC) is more evident with the relatively smaller instantaneous uncut chip thickness, the stable critical cutting depth and its distribution against different tool postures are affected. Considering the nonlinearity, a nonlinear dynamic CFC model that reveals the effect of the dynamic instantaneous uncut chip thickness on the dynamic cutting force is derived based on the Taylor expansion. A five-axis bull-nose end milling dynamics model is established with the nonlinear dynamic CFC model. The stable critical cutting depth distribution with respect to tool posture is analyzed. The stability results predicted with the dynamic CFC model are compared with those from the static CFC model and the constant CFC model. The effects of tool posture and feed per tooth on stable critical cutting depth were also analyzed, and the proposed model was validated by cutting experiments. The maximal stable critical cutting depths that can be achieved under different tool postures by feed per tooth adjustment were calculated, and corresponding distribution diagrams are proposed for milling parameter optimization.

Nowadays many tasks such as medical correlation, surgery and so on almost depend on manpower. Because of occlusions and environmental impacts, artificial intelligence method can help little. For this situation, we design a multicamera stereo vision system which can be used in poor situation to catch and reconstruct certain object. To reduce the environmental impact, infrared devices like cameras, complement lamps and infrared reflection target balls are selected. The system reconstructs object through detecting target balls set on the key position of object instead of directly detect the whole object. When working, the self-adaptive system can choose all or part cameras due to occlusion and lighting conditions to capture pictures containing target spheres. To verify the feasibility and positioning accuracy of this system, we design a 4-DOF mechanical arm and arrange a set of experiments shown in this paper. The whole system can be applied as a real-time and precise auxiliary approach to many object detection tasks such as surgery navigation, position detection and object tracking.

C-peptide is a biomarker that has clinical implications for the diagnosis of a variety of diseases. In this study, an ultrasensitive time-resolved fluorescence lateral flow immunochromatographic assay (TRF-LFIA) method was established for the detection of C-peptides in human serum. The key to this method is the oriented immobilization of antibodies anti C-peptide on TRF microspheres that can sufficiently expose the antigen binding site. The limit of detection (LOD) of this method for C-peptide was 0.005 ng mL

Bayer red mud (RM) occupies a large amount of land, which excessive Na

Efficacious interventions are urgently needed for the treatment of COVID-19. Here, we report a monoclonal antibody (mAb), MW05, showing high SARS-CoV-2 neutralizing activity by disrupting the interaction of receptor binding domain (RBD) with angiotensin-converting enzyme 2 (ACE2) receptor. Crosslinking of Fc with FcγRIIB mediates antibody-dependent enhancement (ADE) activity by MW05. This activity was eliminated by introducing the LALA mutation to the Fc region (MW05/LALA). Most importantly, potent prophylactic and therapeutic effects against SARS-CoV-2 were observed in rhesus monkeys. A single dose of MW05/LALA completely blocked the infection of SARS-CoV-2 in a study of its prophylactic effect and totally cleared SARS-CoV-2 in three days in a treatment setting. These results pave the way for the development of MW05/LALA as an effective strategy for combating COVID-19.

nEXO is a 5 tonne liquid xenon (LXe) time projection chamber (TPC) planned to search for the neutrino-less double beta decay of ${}^{136}$Xe with a target half-life sensitivity of about $10^{28}$ years. Electrons from an event within the TPC will be drifted up to 1.3 m and to ensure minimal charge loss nEXO aims to reach an electron lifetime of 10 ms. This lifetime is inversely proportional to the concentration of electro-negative impurities, for which multiple species with different attachment cross-sections may be important. Various sources for impurities such as diffusion out of commonly used plastics, desorption from metal surfaces and leaks to atmosphere were investigated. We will present the recent measurements of outgassing from plastics and the prospects of an empirically driven model for understanding the electron lifetime in LXe for nEXO.

Extreme events result in significant economic and social disruptions. As an important infrastructure, power transmission systems often have large-scale power outages during extreme events. In order to minimize the loss of power transmission systems under extreme events, this paper proposes a method to devise an optimal maintenance strategy for minimizing maintenance cost. Firstly, a fragility model is established and the Monte Carlo is used to assess the impact of extreme events on power transmission systems. Considering multiple component outages, even system splitting, a power system response model is developed to reflect the operation of power system. Taking into account the maintenance cost and reliability of systems, an optimized model is constructed to devise a post-disaster repair strategy for power transmission systems in a cost-effective manner. Finally, the IEEE 6-bus system is employed to verify the feasibility of the proposed method. In turn, the results provide a reference basis for power companies to carry out power transmission systems emergency planning and post-disaster repair.

The PAHs-C2H2 pathway (PAHs + C2H2 → intermediate → product + H2) has been shown, in theory, to be the important contributor to the growth of polycyclic aromatic hydrocarbons (PAHs) and soot in the post-flame region where H atoms are rare. Calculations of the potential energy surface (PES) using the DFT B3LYP 6-311 + G(d,p) method, and the reaction rate coefficients using the RRKM theory, reveal that armchair and bridge surface sites share similar kinetic characteristics, and are more likely to be the targets of C2H2 molecules in flames compared to zig-zag and 5-membered ring surface sites. Results show that the energy barrier of a 2-H elimination reaction (14–23.8 kcal/mol) is much lower than that of a 1-H elimination (typically 30–40 kcal/mol) for some molecules. The formation of pyrene from phenanthrene via HACA (PAHs + H → PAHs radical (+ C2H2) → intermediate → product + H) and PAHs-C2H2 pathways is investigated using a closed homogeneous zero-dimensional reactor with combustion parameters abstracted from the premixed stagnation C2H4/O2/Ar sooting flame. Results show that the HACA pathway is the dominant pathway for the formation of PAHs and soot surface growth in the main-flame region where H atoms are abundant, but that the PAHs-C2H2 pathway is the preferred pathway in the post-flame region. Our study also suggests that the soot nucleation involving a chemical coalescence of moderate-sized PAHs into a crosslinked three-dimensional structure via the addition reactions of PAHs and PAH radicals in the main-flame region should be considered for inclusion in any soot modeling.

Hydrogen-abstraction/acetylene-addition (HACA) pathway has long been postulated as the dominant pathway for the formation of polycyclic aromatic hydrocarbons (PAHs) and the surface growth of soot. In this study, the site effect on PAH formation following HACA pathway is systematically investigated using density functional theory, transition state theory and premixed flame kinetic modeling. The entire reaction network includes 186 elementary reactions, starting from benzene to pyrene. Analysis of the potential energy surface and kinetic parameters show that H abstraction and C 2 H 2 addition reactions are greatly sensitive to the site position (ortho-, meta- and para-position) relative to the existing C 2 H chain and surface site type (zig-zag, free-edge and armchair). Specifically, H abstraction and C 2 H 2 addition reactions on the ortho-position and armchair surface site are kinetically unsupported due to the relatively high energy barrier and orientation hindrance effect compared with other site options. Therefore, the formation of a new benzene ring by the addition of the second C 2 H 2 molecule on the ortho-position (e.g., 1-ethynylnaphthalene + C 2 H 2 →phenanthrene) or the first C 2 H 2 molecule on the armchair surface site (e.g., phenanthrene + C 2 H 2 →pyrene) is unlikely, as demonstrated by PAH simulations in a premixed C 2 H 4 /O 2 /N 2 sooting flame. The yield distribution of various reaction products has been investigated using a 0-D reactor, where the combustion conditions are taken from experimental data. The results show that the dominant products are di-substituted PAHs in benzene-naphthalene reaction system and PAHs with 5-membered ring structures in larger PAHs reaction systems. The existence of abundant PAHs with 5-membered rings contributes to clarifying the PAHs signal detected using laser induced fluorescence technology. Additionally, the observed sequence of mass peaks at intervals of mass number 26 in C 2 H 2 /C 2 H 4 pyrolysis is reasonably explained by the HACA pathway with considering site effect.

Up-conversion (UC) oxides comprise a huge family of materials with abundant optical functionalities and they merit extensive research. Some members of this family have been modified with proper rare earth (RE3+) ions and their importance has recently been established in non-contact temperature sensors, although the thermal sensitivity (S) value was still low. In this study, we investigated Nd3+ and Yb3+ sensitized Ba4La2Ti4Nb6O30 (BLTN:xNd3+/Yb3+) with a tungsten bronze structure for use as optical thermometers for the first time. Under excitation at 980 nm, obvious near-infrared emissions corresponding to 4F7/2/4S3/2 → 4I9/2, 4F5/2/2H9/2 → 4I9/2, and 4F3/2 → 4I9/2 transitions were observed, and the UC mechanism involved was elaborated. Furthermore, the UC thermometric properties were investigated according to the fluorescence intensity ratio technique and the maximum S values determined for BLTN:xNd3+/Yb3+ (x = 0.12 and 0.16) samples were both higher than 0.03 K–1. The potential of BLTN:xNd3+/Yb3+ for use in optical thermometers was estimated based on comparisons with other active materials.

Reversible upconversion (UC) luminescence modulation by external stimuli (i.e. electric field, magnetic field, and light irradiation) is extremely attractive for applications in a broad range of fields, such as photoswitches, high-density optical data storage devices, and optical sensing. In this work, one kind of novel phosphor, Er3+-doped Bi4Ti3O12 (Bi4−xErxTi3O12) ceramics, prepared by a conventional solid-state reaction approach, is reported which exhibits both bright UC luminescence and a remarkable photochromic (PC) effect. The UC luminescence, PC effect, and the coupling between UC and PC performances were investigated in detail. It is found that the UC luminescence could be readily modulated by alternating visible light irradiation and a thermal stimulus, and a large reversible luminescence regulation has been achieved based on the PC reaction. Meanwhile, the modulation of UC luminescence was shown to tightly depend on the irradiation time and thermal treatment processes. In addition, the coloration and decoloration processes also exhibited good fatigue resistance. The mechanisms related to the UC emissions, PC processes, and luminescence modulation are also discussed. These results indicated that Bi4−xErxTi3O12 samples could be potentially utilized as a kind of optical data storage material.

Day-length changes represent an important cue for modulating flowering time. In Arabidopsis, the expression of the florigen gene FLOWERING LOCUS T (FT) exhibits a 24-h circadian rhythm under long-day (LD) conditions. Here we focus on the chromatin-based mechanism regarding the control of FT expression. We conducted co-immunoprecipitation assays along with LC-MS/MS analysis and identified HD2C histone deacetylase as the binding protein of the H3K4/H3K36 methylation reader MRG2. HD2C and MRG1/2 regulate flowering time under LD conditions, but not under short-day conditions. Moreover, HD2C functions as an effective deacetylase in planta, mainly targeting H3K9ac, H3K23ac and H3K27ac. At dusk, HD2C is recruited to FT to deacetylate histones and repress transcription in an MRG1/2-dependent manner. More importantly, HD2C competes with CO for the binding of MRG2, and the accumulation of HD2C at the FT locus occurs at the end of the day. Our findings not only reveal a histone deacetylation mechanism contributing to prevent FT overexpression and precocious flowering, but also support the model in which the histone methylation readers MRG1/2 provide a platform on chromatin for connecting regulatory factors involved in activating FT expression in response to daylight and decreasing FT expression around dusk under long days.

Cancer immunotherapy is revolutionary in oncology and hematology. However, a low response rate restricts the clinical benefits of this therapy owing to inadequate T lymphocyte infiltration and low delivery efficiency of immunotherapeutic drugs. Herein, an intelligent nanovehicle (folic acid (FA)/1-(4-(aminomethyl) benzyl)-2-butyl-1H-imidazo[4,5-c]quinolin-4-amine (IMDQ)-oxaliplatin (F/IMO)@CuS) armed with multifunctional navigation is designed for the accurate delivery of cargoes to tumor cells and dendritic cells (DCs), respectively. The nanovehicle is based on a near infrared-responsive inorganic CuS nanoparticles, acting as a photosensitizer and carrier of the chemotherapeutic agent oxaliplatin, and enters tumor cells owing to the presence of folic acid on the surface of CuS upon intratumoral injection. Furthermore, a toll-like receptor (TLR) 7/8 agonist-conjugated polymer, anchored on the surface of CuS, is modified with mannose to bind with DCs in the tumor microenvironment. Upon exposure to laser irradiation, nanovehicles disassemble, releasing oxaliplatin, to ablate tumor cells and amplify immunogenic cell death in combination with photothermal therapy. Mannose-modified polymer-TLR7/8 agonist conjugates are subsequently exposed, leading to the activation of DCs and proliferation of T cells. Collectively, these intelligent nanovehicles reduce tumor burden, exert a robust antitumor immune response, and generate long-term immune protection to prevent tumor recurrence.

Extreme weather events do great harm to power distribution systems, causing widespread outages and huge economic losses. It is necessary to investigate the operation and recovery methods for power distribution systems against extreme weather events with small probability and high risk. Accordingly, this paper proposes a cost-optimal operation and recovery method for power distribution systems considering multiple flexible resources and logistics restrictions. The method is developed as a two-stage model to obtain the optimal cost consisting of lost load cost and network loss cost. In the first stage before the disaster, the pre-allocation of repair crews combines multiple flexible resources to cope with the upcoming extreme weather event. In the second stage after the disaster, repair crews coordinate with flexible resources to quickly recover the lost load of the system. The cooperative scheduling of repair crews and flexible resources in the method is restricted by the logistics of transportation networks. Based on the network loss, the two-stage model is formulated as a mixed integer second-order cone programming. The case study conducted on a modified IEEE 33-bus test system demonstrates the effectiveness of the method proposed in this paper.

In recent years, extreme weather events have resulted in a number of severe power outages and economic losses. It is becoming urgent to study approaches to enhance power distribution system resilience. This paper presents a two-stage optimization method for improving resilience of power distribution systems. The two-stage method is influenced by a transportation network, which considers the interdependence between traffic roads and overhead distribution lines. In the first stage, based on the Bayesian network and the Monte Carlo method, the locations of emergency stations, e.g., charging stations and repair stations are pre-positioned to improve the recovery speed of interrupted loads after disasters. Then the second stage is to co-optimize the dispatch of mobile energy storage systems and repair crews on transportation network to minimize the shedding of critical loads while considering operation constraints of power, voltage and power flow for power distribution system. The dispatch of mobile energy storage systems and repair crews are affected by the locations of emergency stations in the first stage. The route of mobile energy storage systems and repair crews on transportation network can be obtained from the results in the second stage. The proposed method is tested on a modified IEEE 33-bus distribution test system with a corresponding transportation network. Simulation results demonstrate the effectiveness of the proposed method in enhancing power distribution system resilience by pre-positioning emergency stations and co-dispatching mobile energy storage systems and repair crews.

This study aims to explore the potential use of fibrous K0.3Ti4O7(OH)1.7 (KTO(OH)) as adsorbent in the enrichment and segregation of Zabuye Salt Lake containing Li+. X-ray diffraction scanning (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infra-red (FTIR) and scanning electron microscopy (SEM) were used to study the phase and morphological properties of KTO(OH). The results showed KTO(OH) was stable in space and had many adsorption sites, with 47.34-m2/g BET surface area. Adsorption capacity is 27.63 mg/g. In addition, pseudo-second-order kinetic model was fitted to verify its adsorption process. After repeating five times, the circulating adsorption capacity can still reach 91.67% of the initial adsorption capacity. The mass loss ratio of KTO(OH) was 0.85% and KTO(OH) shows excellent performance of environmental protection and pollution-free.

The effects of dimethyl ether (DME) addition to ethylene fuel on sooting tendencies with varying pressure were investigated in counterflow diffusion flames by using a laser scattering technique. Sooting limit maps were determined in the fuel (XF) and oxygen (XO) mole fraction plane, separating sooting and non-sooting regions. The results showed that when DME is mixed to ethylene, the sooting region was appreciably shrank, especially in the cases of soot formation/oxidation (SFO) flames as compared with the cases of soot formation (SF) flames. This indicated an inhibiting role of DME on sooting. An interesting observation was that the critical XO required for sooting initially decreased and then increased with the DME mixing ratio to ethylene β for the cases of SF flames, exhibiting a non-monotonic behavior. This implied a promoting role of DME on sooting when small amount of DME is mixed to ethylene. As the pressure increased, the sooting region generally expanded. Specifically, the range of β in promoting soot formation extended with pressure. This implies that a strategy in reducing soot by adding DME to ethylene at high pressures required a large amount of DME addition. To interpret the observed phenomena, kinetic simulations including reaction pathway and sensitivity analyses were conducted with the opposed-flow flames model using the KAUST-Aramco PAH Mech. The results showed that the thermal effect of DME addition on sooting tendency monotonically decreases with β. The chemical effect was found to be the main contributor to the DME addition effect on sooting tendency, resulting in the non-monotonic sooting limt behavior. The pathway analysis showed the role of methyl radicals generated from DME promoted incipient benzene ring formtion when small amount of DME was added, which can be attributed to the soot promoting role of DME addition for small β.

K2Ti4O9, a photocatalyst lacks the response to visible light. This short article takes advantage of the ion exchange properties of K2Ti4O9 and Fe3+ cations that are intercalated to enhance photocatalysis by responding to visible light. The degradation of MB (methylene blue) by K2Ti4O9 treated with different Fe3+ cations amounts was studied, the optimal treatment concentration was determined and the photocatalytic performance was evaluated. The structure, morphology, and energy band characteristics of the photocatalyst were confirmed by XRD, SEM, XPS, UV–vis, PL, and electrochemical workstation.

The various applications of luminescence materials were generally based on the effective modulation of luminescence spectra. However, the research on reversible spectral regulation of up-conversion (UC) luminescence materials was still in its infancy stage. In this work, a class of smart phosphor, Er3+ and Yb3+-codoped SrBi8Ti7O27 (SBYT: xEr3+) intergrowth bismuth layer-structured ferroelectric, possessing fast sensitivity to visible light irradiation, was reported based on visible light driven photochromic effect. Through the alternate stimuli of light irradiation and heating treatment, the reversible regulation of UC luminescence was achieved accompanying with the switching of coloration and decoloration processes. The luminescence modulation degree tightly relied on the irradiation time and thermal treatment modes. The reversibility and stability properties were also revealed. Moreover, it is found that polarization treatment was an effective approach which can be adopted to improve the UC luminescence contrast. The maximum luminescence modulation ability of SBYT: xEr3+ reached up to 81.3% which was 131% of that un-polarized sample. It is believed that SBYT: xEr3+ ceramics can act as a promising candidate for optical data storage and anti-counterfeiting applications.

Highly effective surface-enhanced Raman substrates with shape-diversified silver nanostructures on Al foil (AlF) were fabricated by galvanic replacement reaction in micellar template which is easy to control, simple and cost-effective. Due to the localized surface plasmon resonance (LSPR) of silver nanostructures, the substrates were used as surface enhanced Raman substrates. The shape-diversified silver nanostructures on AlF exhibited stronger surface enhanced Raman scattering (SERS) effects compared with flowerlike Ag nanostructures on ITO glass substrate fabricated by electrodeposition in micellar template. The maximum Raman enhancement factor of 109 fold was obtained, which is 236 times larger than the flowerlike silver nanostructures on ITO glass substrate. The scanning electron microscope (SEM) images show that the size and shape of the nanostructures and surface morphology make a valuable contribution to SERS. Raman enhancement experiments of three Raman probes were studied, which shows that different vibrational modes of Raman probe affect SERS effect. The fabricated shape-diversified silver nanostructures on AlF fabricated by galvanic replacement reaction in micellar template are cheap, controllable and simple. It could be potentially useful in SERS field such as imaging applications and highly sensitive molecule detecting.

The discharging method is most well-known for its central role in the proof of the Four Color Theorem. This proof technique was extensively applied to study various graph coloring problems, in particular on planar graphs. In this paper, we show that suitably altered discharging technique can also be used on domination-type problems. The general discharging approach for domination-type problems is illustrated on a specific domination-type problem, the double Roman domination on some generalized Petersen graphs. By applying this approach, we first prove that $\gamma _{dR}(G) \geq ({3n}/{\Delta (G)+1})$ for any connected graph $G$ with $n\geq 2$ vertices. As examples, we also determine the exact values of the double Roman domination numbers of the generalized Petersen graphs $P(n,1)$ and the double generalized Petersen graphs $DP(n,1)$ . The obtained results imply that $P(n,1)$ is double Roman if and only if $n \not \equiv 2$ (mod 4) and $DP(n,1)$ is double Roman if and only if $n \equiv 0$ (mod 4).

An outer-independent total dominating set (OITDS) of a graph $G$ is a set $D$ of vertices of $G$ such that every vertex of $G$ has a neighbor in $D$ , and the set $V(G)\setminus D$ is independent. The outer-independent total domination number of a graph $G$ , denoted by $\gamma _{oit}(G)$ , is the minimum cardinality of an OITDS of $G$ . An outer-independent total Roman dominating function (OITRDF) on a graph $G$ is a function $f: V(G) \rightarrow \{0, 1, 2\}$ satisfying the conditions that every vertex $u$ with $f(u)=0$ is adjacent to at least one vertex $v$ with $f(v)=2$ , every vertex $x$ with $f(x)\geq 1$ is adjacent to at least one vertex $y$ with $f(y)\geq 1$ , and any two different vertices $a,b$ with $f(a)=f(b)=0$ are not adjacent. The minimum weight $\omega (f) =\sum _{v\in V(G)}f(v)$ of any OITRDF $f$ for $G$ is the outer-independent total Roman domination number of $G$ , denoted by $\gamma _{oitR}(G)$ . A graph $G$ is called an outer-independent total Roman graph (OIT-Roman graph) if $\gamma _{oitR}(G)=2\gamma _{oit}(G)$ . In this paper, we propose dynamic programming algorithms to compute the outer-independent total domination number and the outer-independent total Roman domination number of a tree, respectively. Moreover, we characterize all OIT-Roman graphs and give a linear time algorithm for recognizing an OIT-Roman graph.

Adsorption is an effective method to remove heavy metal from water. Here, this paper reported that potassium titanate whiskers exhibit excellent performance for adsorbing heavy metals in wastewater. Potassium tetratitanate whiskers were successfully prepared by the improved solid phase method. The adsorption kinetics, adsorption isotherm, competitive adsorption and regeneration performance for Pb(II), Cd(II), and Cu(II) cations were studied. During the static adsorption process, the maximum saturated adsorbed amount of Pb(II), Cd(II), and Cu(II) cations were up to 319 mg/g, 247 mg/g, 185 mg/g, respectively. The kinetic characteristics were suitable for pseudo-second-order model description, and the isothermal characteristics could be explained by Freundlich model. The adsorption mechanism showed that surfaces and pores of 4-PTW are important adsorption areas, and the results of XRD and XPS proved the unique layered structure of K2Ti4O9 enabled the exchange of K(I) cations with heavy metal cations. The competitive adsorption results that the heavy metal cations with a small radius and strong electronegativity were easier to be captured by 4-PTW. The adsorption capacity retained more than 70% after five cycles, shows a good recycling performance. In summary, the adsorption performance of potassium titanate whiskers was evaluated and the adsorption mechanism was explained.

s Furan is one of the smallest organic compounds with heterocycle ring. With this particular molecular structure, furan is considered as a highly toxic and carcinogenic combustion pollutant, and furan may contribute to the formation of oxygenated soot. In this work, furan formation pathways from 1,3-butadiene, trans-2-butene and cis-2-butene were comprehensively explored. The potential energy surfaces, reaction rate coefficients, and thermodynamics were calculated by quantum chemistry using high level of theories including the CCSD (T) and G3 methods. The proposed reaction pathways were then implemented into the AramcoMech 3.0 model uniformly or independently to examine the model performance with the experimental data. The oxidation experiments of 1,3-butadiene, trans-2-butene and cis-2-butene were performed in a jet stirred reactor (JSR) in the low temperature regime (500–830 K). The JSR is coupled with time-of-flight molecular beam mass spectrometry (ToF-MBMS) using synchrotron radiation as photon ionization source for species identification and quantification. Compared with experiments, both updated models (the independent and uniform model) showed better prediction of furan than the base AramcoMech 3.0 model, which highlighted the contribution of the proposed pathways. Reaction pathway analyses reveal that in the proposed reaction pathway, both reactions C4H6 + OH ⇌ S1–4 (H2C CH-ĊH CH2OH, but‑1-en-3-yl-4-ol) and C4H6 + HO2 ⇌ C4H61–3OOH4 (H2C CH-ĊH CH2OOH, but‑1-en-3-yl-4-peroxide) not only contribute to furan formation, but also to fuel consumption. Furthermore, the kinetic uncertainty from activation energy calculated by the CCSD series methods, CBS-ANPO, and G4 methods was evaluated for reaction C4H6 + HO2 ⇌ C4H61–3OOH4. Instead of developing a new kinetic model, this work aims at proposing and validating new reaction pathways to advance the understanding of furan formation chemistry in low temperature oxidation, and provide guidance for future model development.

A general approach to asymmetrically localize nanoparticles (NPs) in larger polymeric nanostructures is demonstrated by coassembly of tadpole-like silver NPs (AgNPs) and amphiphilic block copolymers (BCPs). The tadpole-like AgNPs are prepared by template synthesis using a tailor-made A(BC)20 star polymer, namely poly(ethylene glycol)[poly(acrylic acid)-block-polystyrene]20 [PEG(PAA-b-PS)20 ], as template resulting in AgNPs decorated with twenty short PS chains and one long PEG chain, named Ag@PEG(PS)20 . The asymmetric distribution of these AgNPs in various polymeric nanostructures, e.g., spherical micelles, cylindrical micelles, vesicles, and sponge phase, is achieved via coassembly of the as-prepared Ag@PEG(PS)20 and PEG-b-PS in solution driven by the anisotropic nature of the Ag@PEG(PS)20 . This report not only provides a new strategy for the fabrication of tadpole-like NPs but also offers opportunity for off-center distributing NPs in hybrid assemblies, which may find applications in, e.g., sensing, catalysis, and diagnostics.

The total photovoltaic (PV) installed capacity of China plans to increase above 56 GW by 2050 to realize the goals of carbon peak and carbon neutrality. As a result, the hosting capacity of PV in a power distribution system affects the operation performance such as the quality of voltage, power balance, stability, and frequency problems. To investigate impacts of different PV penetration levels on the voltage and feeder in a typical power distribution network, this work considers uncertainties of PV output, and a Monte Carlo-based method is employed to simulate the impacts for different PV penetration levels on a power distribution network to evaluate voltage deviation from the normalized level (0.9 to 1.1 p.u.). A typical IEEE 33-bus system is studied and the connected PVG is based on 10-min resolution historical data from California in America in 2006. Results of the studied power distribution network are showed under three different cases: underloaded, overloaded, and fully-loaded that the 33-bus system injected with a higher PV penetration causes more voltage problems on the buses as well as the main feeder utilization tends to increase when the distribution system is underloaded or overloaded.

Acoustic mode detection is attached great significance for providing guidance to noise reduction design of commercial aero-engine with high-bypass ratio. Compressive sampling method has been creatively employed in this field due to its notable performance on reducing the number of microphones in acoustic mode measurements. However, the classical l 1 -norm regularized compressive sampling model tends to underestimate the dominant mode amplitudes of interest. Moreover, the traditional regularization parameter selection strategy with fixed threshold brings out inefficient and cumbersome work. In this paper, we propose a nonconvex penalized compressive sampling model with adaptive threshold, to seek the sparse and accurate solution of acoustic mode detection from limited measurements, and provide a sufficiently efficient way to adaptively seek the optimal regularization parameter. Firstly, the reweighted generalized minimax-concave (ReGMC) regularization is employed to improve the accuracy of acoustic pressure reconstruction, which feasibly enhances sparsity with maintaining the convexity of the cost function. Secondly, the k-sparsity strategy is introduced to set regularization parameters adaptively. Finally, the applicability of the proposed approach is verified on a multi-stage aero-engine fan test rig. Experimental results demonstrate that the nonconvex ReGMC regularized method outperforms the classical l 1 -norm, producing more accurate results in mode detection with fewer measurements and being more robust towards background noise.

Numerous experimental and theoretical evidence indicates that polycyclic aromatic hydrocarbon (PAH) is the precursor of soot. However, the formation mechanism of PAH at flame conditions is not well understood. In this study, the growth of PAHs with a 5-membered ring via the hydrogen-abstraction-acetylene-addition route was systematically investigated using acenaphthylene (A2R5) as a model molecule. Potential energy surfaces were searched using DFT/B3LYP/6-311+G(d,p) and ROCCSD(T)/cc-pVDZ methods. The reaction rate coefficients of elementary reactions were evaluated using the transition state theory in the temperature range of 500–2500 K. The results showed that H abstractions by H, OH, and CH3 radicals, and the subsequent C2H2 addition reactions, were highly sensitive to the 5-membered ring. H abstraction reaction from the C atom on a 5-membered ring is not favorable due to the relatively higher energy barrier among all competing reactions. In contrast, the reaction rate coefficient of subsequent C2H2 addition reaction on a 5-membered ring is the highest. The planar PAH with no substitution, planar PAH with C2H substitution, curved PAH with two adjacent 5-membered rings, and PAH with a C CH2 C functional group, can be formed in the A2R5 H-C2H2 system investigated. The reactions investigated were merged into a detailed PAH mechanism to check the product distribution in a premixed C2H4 sooting flame. Owing to the existence of the 5-membered ring, the formation of planar PAHs with a C2H substitution was much more favorable than the formation of new 5-membered ring and 6-membered rings. The predicted mole fraction of all C14H8 species with one C2H substitution was as high as 2.8 × 10−5, higher than that of phenanthrene with same C atom number (1.2 × 10−5). A similar phenomenon was observed for C16H8 species with two C2H substitutions. In the future, more attention should be given to PAHs with C2H substitution, due to their high concentrations and enhanced reactivity, as compared to the benzenoid PAH.

In the optimization process of five-axis cutting direction and cutter orientation, the cutter/workpiece engagement (CWE) region and cutting forces vary with different machining parameters; the prediction of CWE region is still a challenge especially for bullnose end mills. This paper presents a method to model the CWE boundaries of bullnose end cutters as a function of the five-axis parameters: the lead angle, the tilt angle, the cutting depth, and the path interval. In this method, the CWE boundaries are determined by three boundary curves: the characteristic of the envelope, the intersection of the envelop and the workpiece surface, and the projective of the previous characteristic curve in the feed direction. Based on the symbolically solvable CWE boundary model, margin height method to determine the in-cutting edge is proposed, which is validated obviously much faster than Z-map method. Using margin height method to calculate the upper and lower limits of the cutting edge, the algebraic method to predict cutting force is described and validated by five-axis machining experiment for a bullnose end cutter. The cutting force is simulated without discretizing along the cutter axis, and the calculating efficiency is improved largely comparing with the traditional method that accumulated the differential forces element by element. The symbolically solvable CWE model and margin height method-based cutting force model are very suitable for optimizing cutting direction and cutter orientation in five-axis machining.

Super-Kamiokande is a 50 kton water Cherenkov detector, which has been in operation since 1996. Super-Kamiokande atmospheric neutrino data have a preference for the normal neutrino mass hierarchy ( Δ χ 2 = χ N H 2 − χ I H 2 = − 4.3 ) when the constraints from reactor neutrino experiments are included. The search for tau neutrino appearance from neutrino oscillations has resulted in a 4.6σ exclusion of the hypothesis of no tau appearance. Hyper-Kamiokande is a proposed next-generation water Cherenkov detector, which will be a natural extension of Super-Kamiokande. The proposed experiment will have two cylindrical tanks containing 520 kton of water in total. Hyper-K will search for CP violation using the neutrino beam from J-PARC, and will have a broad physics program including studies of atmospheric neutrinos, supernova burst neutrinos, geo-neutrinos and searches for proton decay.

A graceful labeling of a graph $G=(V,E)$ with $m$ edges is an‎ ‎injection $f‎: ‎V(G) \rightarrow \{0,1,\ldots,m\}$ such that the resulting edge labels‎ ‎obtained by $|f(u)-f(v)|$ on every edge $uv$ are pairwise distinct‎. ‎For natural numbers $n$ and $k$‎, ‎where $n > 2k$‎, ‎a generalized Petersen‎ ‎graph $P(n‎, ‎k)$ is the graph whose vertex set is $\{u_1‎, ‎u_2‎, ‎\ldots‎, ‎u_n\} \cup \{v_1‎, ‎v_2‎, ‎\ldots‎, ‎v_n\}$ and‎ ‎its edge set is $\{u_iu_{i+1}‎, ‎u_iv_i‎, ‎v_iv_{i+k}‎ : ‎1 \leq i \leq n \}$‎, ‎where‎ ‎subscript arithmetic is done modulo $n$‎. ‎We propose a backtracking algorithm with a specific static variable ordering and dynamic value ordering to‎ ‎find graceful labelings for generalized Petersen graphs‎. ‎Experimental results show that the presented approach strongly outperforms the standard backtracking algorithm‎. ‎The proposed algorithm is able to find graceful labelings for all‎ ‎generalized Petersen graphs $P(n‎, ‎k)$ with $n \le 75$ within only several seconds.

Given a positive integer t and a graph F, the goal is to assign a subset of the color set $$\{1,2,\ldots ,t\}$$ to every vertex of F such that every vertex with the empty set assigned has all t colors in its neighborhood. Such an assignment is called the t-rainbow dominating function ( $$t\mathrm{RDF}$$ ) of the graph F. A $$t\mathrm{RDF}$$ is independent ( $$It\mathrm{RDF}$$ ) if vertices assigned with non-empty sets are pairwise non-adjacent. The weight of a $$t\mathrm{RDF}$$ g of a graph F is the value $$w(g) =\sum _{v \in V(F)}|g(v)|$$ . The independent t-rainbow domination number $$i_{rt}(F)$$ is the minimum weight over all $$It\mathrm{RDF}$$ s of F. In this article, it is proved that the independent t-rainbow domination problem is NP-complete even if the input graph is restricted to a bipartite graph or a planar graph, and the results of the study provide some bounds for the independent t-rainbow domination number of any graph for a positive integer t. Moreover, the exact values and bounds of the independent t-rainbow domination numbers of some Petersen graphs and torus graphs are given.

The Taishan Antineutrino Observatory (TAO) is proposed to first use a cold liquid scintillator detector (-50~$^\circ$C) equipped with large-area silicon photomultipliers (SiPMs) ($\sim$10~m$^2$) to precisely measure the reactor antineutrino spectrum with a record energy resolution of < 2\% at 1 MeV. The KLauS ASIC shows excellent performance at room temperature and is a potential readout solution for TAO. In this work, we report evaluations of the fifth version of the KLauS ASIC (KLauS5) from room temperature to -50~$^\circ$C with inputs of injected charge or SiPMs. Our results show that KLauS5 has good performance at the tested temperatures with no significant degradation of the charge noise, charge linearity, gain uniformity or recovery time. Meanwhile, we also observe that several key parameters degrade when the chip operates in cold conditions, including the dynamic range and power consumption. However, even with this degradation, a good signal-to-noise ratio and good resolution of a single photoelectron can still be achieved for the tested SiPM with a gain of greater than 1.5$\times$10$^6$ and even an area of SiPM up to 1~cm$^2$ in one channel, corresponding to an input capacitance of approximately 5~nF. Thus, we conclude that KLauS5 can fulfill the TAO requirements for precise charge measurement., 15 pages, 12 figures, aticle

Although there was significant advancement on polycyclic aromatic hydrocarbon (PAH) formation, current mechanisms are still limited in providing an integrated and accurate scheme of PAH yield in combustion conditions; thus, a more detailed and comprehensive understanding is necessary. This work provides a systematic investigation of PAH growth by phenylacetylene addition. A combination of the density functional theory (DFT/B3LYP/6-311+G(d,p)) and the complete basis set method (CBS-QB3) is utilized to calculate the potential energy surfaces. The reaction system is initiated by the H elimination reaction of phenylacetylene + H →

Soot particles alter global climate and dominate the origin and evolution of carbonaceous interstellar material. Convincing experimental evidence has linked polycyclic aromatic hydrocarbons (PAH) to soot inception under low-temperature astrochemistry and high-temperature combustion conditions. However, significant gaps still remain in the knowledge of PAH and soot formation mechanisms. Here, we report theoretical and experimental evidence for a soot inception and growth pathway driven by peri-condensed aromatic hydrocarbons (PCAH) with an alkynyl substitution. Initially, free radicals attack the α-alkynyl substitution of PCAHs to form covalently bound compounds yielding resonantly stabilized radicals (RSRs), which promote further clustering through repeated addition reactions with negligible energy barriers. The proposed pathway is shown to be competitive at temperatures relevant to astrochemistry, engine exhaust manifold and flames because it does not require H-abstraction reactions, the requisite reaction precursors are in abundance, and the reaction rate is high. Such addition reactions of PCAHs with α-alkyne substituents create covalently bound clusters from moderate-size PAHs that may otherwise be too small to coagulate.

A modified stochastic averaging method on a Duffing-Rayleigh oscillator with strongly nonlinearity subject to Gaussian colored noise excitation was proposed. The so-called He’s energy balance method was applied to obtain the averaged frequency of the conservative system. Subsequently, the stochastic averaging method of strong nonlinearity was used. The modified method can offer more concise approximate expressions of the drift and diffusion coefficients without weakening the accuracy of predicting the responses of the systems too much. The stationary responses of probability density of amplitudes, together with joint probability density of displacement and velocity are studied to verify the presented approach. The reliability of the systems was also investigated to offer further support. Digital simulations were carried out and the output of that are coincide with the theoretical approximations well.

A modified stochastic averaging method on single-degree-of-freedom (SDOF) oscillators under white noise excitations with strongly nonlinearity was proposed. Considering the existing approach dealing with strongly nonlinear SDOFs derived by Zhu and Huang [14, 15 ] is quite time consuming in calculating the drift coefficient and diffusion coefficients and the expressions of them are considerable long, the so-called He's energy balance method was applied to overcome the minor defect of the Zhu and Huang's method. The modified method can offer more concise approximate expressions of the drift and diffusion coefficients without weakening the accuracy of predicting the responses of the systems too much by giving an averaged frequency beforehand. Three examples, a cubic and quadratic nonlinearity coexisting oscillator, a quadratic nonlinear oscillator under external white noise excitations and an externally excited Duffing–Rayleigh oscillator, were given to illustrate the approach we proposed. The three examples were excited by the Gaussian white noise and the Gaussian colored noise separately. The stationary responses of probability density of amplitudes and energy, together with joint probability density of displacement and velocity are studied to verify the presented approach. The reliability of the systems were also investigated to offer further support. Digital simulations were carried out and the output of that are coincide with the theoretical approximations well.

A giant magnetostrictive thin film (GMF) actuator designed as a simply supported beam under axial white noise excitation is studied. Firstly, a non-dimensional stochastic difference equation governing the motion is simplified by the modified stochastic averaging method. Subsequently, the stationary probability density function of amplitude and the joint probability density function of displacement and velocity were obtained respectively. Finally, the reliability was studied by the backward Kolmogorov (BK) equation to guarantee the safety of the actuator. Numerical simulations are carried out to verify the theoretical analysis.

In situ Raman vibration characterization and angle-dispersive X-ray diffraction (ADXD) measurements were performed on Y2O3/Eu3+ nanotubes to study its lattice change behavior under high pressure. The Raman vibration and lattice reflection both show changes in behavior near 8–10 GPa. The lattice of the cubic structure of Y2O3/Eu3+ nanotubes exhibits two different lattice states related to forms of the micro local atom arrangement. The lattice states resulted from the local disorder of the lattice due to pressure-induced deformation of the YO6 octahedra under the high pressure.

Complex aerospace parts with difficult-to-cut materials AerMet100 etc. should be processed by five-axis milling at low spindle speed, in which the process damping cannot be ignored in stability analysis. Based on the established nonlinear process damping and relevant equivalent process damping coefficient model, a 3D stability lobe diagram (SLD) considering the finite amplitude stability is proposed. A novel indentation coefficient identification method of the nonlinear process damping is proposed by using the finite amplitude stability region, which avoiding the experiment identification of accurate critical cutting depth in inverse stability solution method, and a turning experiment is designed to identify the indentation coefficient of AerMet100 materials. Due to the distribution of process damping force is varied with the cutter-workpiece engagement (CWE) which can be changed by tool orientation, thus the critical cutting depth with considering or not the process damping under different tool orientation are compared and analyzed. The results indicate that critical cutting depth magnitude distribution can be affected by the process damping, and the percentage increase in cutting depth has significant relationship with tool orientation and the frequency response function (FRF). Finally, the influence rule of tool orientation on stability boundary is concluded and the optimization criteria is given.