A life prediction method based on MDFF and DITCN-ABiGRU mixed network model.

A single network model exhibits limitations in the life prediction of rotating machinery for the various fault types and uncertain fault occurrence. Therefore, a network prediction model combining multi-domain feature fusion (MDFF) and distributed TCN-Attention-BiGRU (DITCN-ABiGRU) is proposed to enable a more accurate life prediction of rotating machinery. Firstly, the features of vibration signals collected from multiple sensors are extracted in the time, frequency, and time-frequency domains.

Dynamic distribution of spp. in sewage, substrate, plant rhizosphere/phyllosphere and air of constructed wetland ecosystem.

Introduction: bacteria are widely distributed and have various ecological functions. Preliminary studies have shown that is the dominant species in constructed wetland ecosystems, but its species composition and distribution in constructed wetlands are still unclear.

Methods: In this paper, the in-house-designed primers were used to construct a 16S rDNA clone library of .

Roles of Amides on the Formation of Atmospheric HONO and the Nucleation of Nitric Acid Hydrates.

Nitrous acid (HONO) is hazardous to the human respiratory system, and the hydrolysis of NO is the source of HONO. Hence, the investigation on the removal and transformation of HONO is urgently established. The effects of amide on the mechanism and kinetics of the formation of HONO with acetamide, formamide, methylformamide, urea, and its clusters of the catalyst were studied theoretically.

FeO/FeNC modified activated carbon packing media for biological slow filtration to enhance the removal of dissolved organic matter in reused water.

The biological slow filtration reactor (BSFR) process has been found to be moderately effective for the removal of refractory dissolved organic matter (DOM) in the treatment of reused water. In this study, bench scale experiments were conducted using a mixture of landscape water and concentrated landfill leachate as feed water, to compare a novel iron oxide (FeO)/FeNC modified activated carbon (FeO@AC) packed BSFR, with a conventional activated carbon packed BSFR (AC-BSFR), operated in parallel. The results showed that the FeO@AC packed BSFR had a refractory DOM removal rate of 90%, operated at a hydraulic retention time (HRT) of 10 h at room temperature for 30 weeks, while under the same conditions the removal by the AC-BSFR was only 70%.

Effects of potassium monopersulfate on nitrification activity and bacterial community structure of sponge biocarrier biofilm in aquaculture system.

Effects of potassium monopersulfate (KMPS) on the nitrification activity, aquacultural water quality and bacterial community structure of sponge biocarriers with pre-cultured biofilm (SBBF) were analysed through shaking flask experiments and aquaculture experiments. Changes in the ammonia oxidation rate (AOR) and nitrite oxidation rate (NOR) of SBBF under six KMPS concentration treatments (0, 1, 2, 3, 4 and 5 mg/L) were studied. The results showed that the AOR and NOR of SBBF treated with high concentrations of KMPS (3, 4 and 5 mg/L) were significantly lower than those of the control group (CK) ( < 0.

Theoretical insights into the gaseous and heterogeneous reactions of halogenated phenols with ˙OH radicals: mechanism, kinetics and role of (TiO) clusters in degradation processes.

Halogenated phenols are highly toxic chemicals with serious health risks, and the removal of these persistent environmental pollutants remains a challenge. Based on quantum chemistry calculations, the homogeneous/heterogeneous degradation mechanism and kinetics of CXOH (X = F, Cl, and Br) initiated by ˙OH radicals in the gas phase and TiO cluster surfaces are investigated in this work. Four ˙OH-addition and one proton-coupled electron-transfer (PCET) reaction channels for each halogenated phenol were found and the ˙OH-addition channels were more favorable than the PCET pathway without TiO clusters.

A Comparative Study of the Properties of Recycled Concrete Prepared with Nano-SiO and CO Cured Recycled Coarse Aggregates Subjected to Aggressive Ions Environment.

This research focused on the modification effects on recycled concrete (RC) prepared with nano-SiO and CO cured recycled coarse aggregates (RCA) subjected to an aggressive ions environment. For this purpose, RCA was first simply crushed and modified by nano-SiO and CO respectively, and the compressive strength, ions permeability as well as the macro properties and features of the interface transition zone (ITZ) of RC were investigated after soaking in 3.5% NaCl solution and 5% NaSO solution for 30 days, respectively.

Formation factors and hazard evaluation of halogenated methyl sulfonic acid in drinking water.

Halogenated methyl sulfonic acid (HMSAs) is a new type of disinfection by-product recently reported, and there are few relevant studies, so its source and harm are still unclear. This study mainly discusses the source of halogenated methyl sulfonic acid from the macroscopic level and evaluates the harm to human health. This study clarified that chlorine disinfection is one of the main ways of generating halogenated methyl sulfonic acids (HMSAs) in drinking water.

DFT analysis on the removal of dimethylbenzoquinones in atmosphere and water environments: ·OH-initiated oxidation and captured by (TiO) clusters (n=1-6).

The elimination mechanisms and the dynamics of 2,5-dimethylbenzoquinone/2,6-dimethylbenzoquinone are performed by DFT under the presence of ·OH radical and TiO-clusters. The rate coefficients, calculated within the atmospheric and combustion temperature range of 200-2000 K, agree well with the experimental data. The subsequent reactions including the bond cleavage of quinone ring, O addition or abstraction, the reactions of peroxy radical with NO yielding the precursor of organic aerosol are studied.

Ciprofloxacin transformation in aqueous environments: Mechanism, kinetics, and toxicity assessment during OH-mediated oxidation.

The initial reactions of organics with OH are important to understand their transformations and fates in advanced oxidation processes in aqueous phase. Herein, the kinetics and mechanism of OH-initiated degradation of ciprofloxacin (CIP), an antibiotic of fluoroquinolone class, are obtained using density functional and computational kinetics methods. All feasible mechanisms are considered, including H-abstraction, OH-addition, and sequential electron proton transfer.

New insights into 3M3M1B: the role of water in ˙OH-initiated degradation and aerosol formation in the presence of NO (X = 1, 2) and an alkali.

The oxidation mechanisms and dynamics of 3-methoxy-3-methyl-1-butanol (3M3M1B) initiated by ˙OH radicals were assessed by the density functional theory and canonical variational transition state theory. The effects of ubiquitous water on the title reactions were analyzed by utilizing an implicit solvation model in the present system. The results suggested that aqueous water played a negative role in the ˙OH-initiated degradation of 3M3M1B with an increase in the Gibbs free barriers.

Effects of soil nitrogen (N) deficiency on photosynthetic N-use efficiency in N-fixing and non-N-fixing tree seedlings in subtropical China.

Soil nitrogen (N) deficiencies can affect the photosynthetic N-use efficiency (PNUE), mesophyll conductance (g), and leaf N allocation. However, lack of information about how these physiological characteristics in N-fixing trees could be affected by soil N deficiency and the difference between N-fixing and non-N-fixing trees. In this study, we chose seedlings of two N-fixing (Dalbergia odorifera and Erythrophleum fordii) and two non-N-fixing trees (Castanopsis hystrix and Betula alnoides) as study objects, and we conducted a pot experiment with three levels of soil N treatments (high nitrogen, set as Control; medium nitrogen, MN; and low nitrogen, LN).

Seedling leaves allocate lower fractions of nitrogen to photosynthetic apparatus in nitrogen fixing trees than in non-nitrogen fixing trees in subtropical China.

Photosynthetic-nitrogen use efficiency (PNUE) is a useful trait to characterize leaf physiology and survival strategy. PNUE can also be considered as part of 'leaf economics spectrum' interrelated with leaf nutrient concentrations, photosynthesis and respiration, leaf life-span and dry-mass investment. However, few studies have paid attention to PNUE of N-fixing tree seedlings in subtropical China.

A quantum theory investigation on atmospheric oxidation mechanisms of acrylic acid by OH radical and its implication for atmospheric chemistry.

The hydroxyl radical, as the most important oxidant, controls the removal of some volatile organic compounds (VOCs) in the atmosphere. In this work, the atmospheric oxidation processes of acrylic acid by OH radical have been investigated by density functional theory (DFT). The energetic routes of the reaction of CHCHCOOH with OH radical have been calculated accurately at the CCSD(T)/cc-pVTZ//M06-2X/6-311++G(d,p) level.

Speciation analysis of mercury by dispersive solid-phase extraction coupled with capillary electrophoresis.

A pretreatment method of dispersive solid-phase extraction (DSPE) along with back-extraction followed by CE-UV detector was developed for the determination of mercury species in water samples. Sulfhydryl-functionalized SiO microspheres (SiO -SH) were synthesized and used as DSPE adsorbents for selective extraction and enrichment of three organic mercury species namely ethylmercury (EtHg), methylmercury (MeHg), and phenylmercury (PhHg), along with L-cysteine (L-cys) containing hydrochloric acid as back-extraction solvent. Several main extraction parameters were systematically investigated including sample pH, amount of adsorbent, extraction and back-extraction time, volume of eluent, and concentration of hydrochloric acid.

Identifying critical components causing seasonal variation of activated sludge settleability and developing early warning tool.

Settleability of activated sludge is one of the most common problems that restricts the efficiency of activated sludge system. Obvious seasonal variation of settleability was found in the activated sludge system of a full scale wastewater treatment plant (WWTP) during 2 years of observation. Principal component analysis (PCA) was applied to study the correlation between diluted sludge volume index (DSVI), operational and environmental factors.

Study on diesel vertical migration characteristics and mechanism in water-bearing sand stratum using an automated resistivity monitoring system.

Oil spills frequently occur on both land and sea. Petroleum in mobile phase will cause serious pollution in the sediment and can form a secondary pollution source. Therefore, it is very important to study the migration of petroleum in sediments ideally in a rapid and simplified approach.

Interfacial Connection Mechanisms in Calcium-Silicate-Hydrates/Polymer Nanocomposites: A Molecular Dynamics Study.

Properties of organic/inorganic composites can be highly dependent on the interfacial connections. In this work, molecular dynamics, using pair-potential-based force fields, was employed to investigate the structure, dynamics, and stability of interfacial connections between calcium-silicate-hydrates (C-S-H) and organic functional groups of three different polymer species. The calculation results suggest that the affinity between C-S-H and polymers is influenced by the polarity of the functional groups and the diffusivity and aggregation tendency of the polymers.

Molecular Simulation of the Ions Ultraconfined in the Nanometer-Channel of Calcium Silicate Hydrate: Hydration Mechanism, Dynamic Properties, and Influence on the Cohesive Strength.

Reactive force field molecular dynamics was utilized to investigate the structure, dynamics, and mechanical nature of different cations solvated in the nanometer-channel of highly disordered calcium silicate hydrate. The local structures of different cations bonded with hydroxyl groups are characterized by the long spatial correlation, bond angel distribution preference, and featured coordinated number, resembling those of the tetra-/penta-/octahedron for cation-oxygen structure in the defective region of the silicate glass. Al atoms in the interlayer region play a role in bridging the defective silicate chains and enhance the connectivity of the silicate skeleton.

Symmetry analysis of transport properties in helical superconductor junctions.

We study the discrete symmetries satisfied by helical p-wave superconductors with the d-vectors [Formula: see text] or [Formula: see text] and the transformations brought by symmetry operations to ferromagnet and spin-singlet superconductors, which show intimate associations with the transport properties in heterojunctions, including helical superconductors. In particular, the partial symmetries of the Hamiltonian under spin-rotation and gauge-rotation operations are responsible for the novel invariances of the conductance in tunnel junctions and the new selection rules for the lowest current and peculiar phase diagrams in Josephson junctions, which were reported recently. The symmetries of constructed free energies for Josephson junctions are also analyzed, and are consistent with the results from the Hamiltonian.

Defect enabled formation of multilayered funnel from isolated graphene nanoring.

Molecular dynamics simulations demonstrate that the cut defect can induce and guide the self-assembly of an isolated graphene nanoring (GNR) to form multi-layered funnel morphology. The vdW force is the driving force; the tangent component drives the self-assembly of GNR and the normal component adjusts and maintains the vertical distance between graphene layers, which is two times of the vdW radius. Moreover, the offset π-π stacking aids the adjacent layers to achieve the lowest energy of AB stacking.

Metal organic frameworks (MOFs) for magnetic solid-phase extraction of pyrazole/pyrrole pesticides in environmental water samples followed by HPLC-DAD determination.

Magnetic metal-organic frameworks (MOFs, [MIL-101]) were prepared and used as magnetic solid-phase extraction (MSPE) adsorbents for preconcentration of four kinds of pyrazole/pyrrole pesticides (flusilazole, fipronil, chlorfenapyr, and fenpyroximate) in environmental water samples, followed by high-performance liquid chromatography-diode-array detector (HPLC-DAD) determination. Several variables affecting MSPE efficiency were systematically investigated, including amount of MIL-101, extraction time, sample pH, salt concentration, type of desorption solvent and desorption number of times. Under optimized conditions, excellent linearity was achieved in the range of 5.

Switch on the high thermal conductivity of graphene paper.

This work reports on the discovery of a high thermal conductivity (κ) switch-on phenomenon in high purity graphene paper (GP) when its temperature is reduced from room temperature down to 10 K. The κ after switch-on (1732 to 3013 W m K) is 4-8 times that before switch-on. The triggering temperature is 245-260 K.

Determination of six sulfonylurea herbicides in environmental water samples by magnetic solid-phase extraction using multi-walled carbon nanotubes as adsorbents coupled with high-performance liquid chromatography.

Magnetic solid-phase extraction (MSPE) using magnetic multi-walled carbon nanotubes (mag-MWCNTs) as adsorbents, coupled with high-performance liquid chromatography-diode-array detector (HPLC-DAD), was developed for the simultaneous separation and determination of six types of sulfonylurea herbicides (SUs) in environmental water samples. Several variables affecting MSPE efficiency were systematically investigated, including the type and volume of desorption solvent, sample solution pH, salt concentration, amount of mag-MWCNTs, and extraction and desorption time. Response surface was employed to assist in the MSPE optimization.

Increasing the CO2 /N2 Selectivity with a Higher Surface Density of Pyridinic Lewis Basic Sites in Porous Carbon Derived from a Pyridyl-Ligand-Based Metal-Organic Framework.

The development of functional porous carbon with high CO2 /N2 selectivity is of great importance for CO2 capture. In this paper, a type of porous carbon with doped pyridinic sites (termed MOFC) was prepared from the carbonization of a pyridyl-ligand based MOF. Four MOFCs derived from different carbonizing temperatures were prepared.