Search Results (85)

Many US states have adopted regulations to divert food waste from landfills to composts. While this may lower greenhouse emissions from landfills, volatile organic compound (VOC) emissions from compost may contain hazardous air pollutants or produce odors, posing potential public health concerns. Effective methods to analyze speciated VOCs in compost are needed to better understand VOC source generation. Here, a two-component compost sampling method was developed and employed consisting of a chilled impinger and pump apparatus to trap water-soluble VOCs, and dual sorbent tubes to capture hydrophobic VOCs in yard and food/yard waste compost. VOCs were measured via headspace gas chromatography with flame ionization detection (HS-GC-FID) and thermal desorption–gas chromatography–mass spectrometry (TD-GC-MS). Overall, there was higher VOC generation within higher-temperature compost piles, with concentrations ranging up to 27,000 ppm for ethanol and 3500 ppm for methanol. Alpha-pinene and D-limonene were seen in these piles with concentrations over 1600 ppb. Methanol and ethanol were more than one thousand times as concentrated in mixed food/yard waste than yard waste alone, while terpenes were seen in slightly higher concentrations for yard waste than the mixed food/yard waste. Methanol was observed to be higher than permissible indoor levels and may pose potential health risks. Full article

Background: This study presents a sensitive method for the simultaneous determination of organic acids, flavonoids, and amino acids in Mume Fructus (MF) using ultra-performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry (UPLC-QTRAP-MS/MS). Methods: Analysis was performed on a UPLC system (Shimadzu, Kyoto, Japan) equipped with a quaternary pump solvent management system, an online degasser, a triple-quadrupole mass detector, and an autosampler. An Agilent ZORBAX SB-C18 column (3.0 mm × 100 mm, 1.8 µm) was used for chromatographic analyses. The mobile phase was distributed between 0.2% aqueous formic acid (A) and 0.2% formic acid acetonitrile (B) at a velocity of 0.2 mL/min. The gradient evolution protocol was 0–2 min at 90–70% B; 3–7 min at 70–50% B; 7–10 min at 50–20% B; 10–14.5 min at 20–90% B; and 14.5–17 min at 10% B. Results: The method was validated for matrix effects, linearity, limits of detection/quantification, precision, repeatability, stability, and recovery of target components. It effectively determined all target compounds in 12 MF batches from different drying methods. Conclusions: Principal component analysis (PCA) of 47 active components was conducted to evaluate MF quality comprehensively. The proposed method serves as a reliable approach for assessing the consistency of MF’s quality and therapeutic efficacy. Full article

This study explores the correlation between road surface texture, including microtexture (texture depth) and macrotexture (wavelength) in asphalt pavement, and suspended dust generation on asphalt pavements. A detailed analysis of various pavement types, including Hot Mix Asphalt (HMA) and porous pavement, was conducted to assess their impact on dust load and concentration. For HMA pavements, deeper texture depths led to a higher dust load and concentration, attributed to the impermeable nature of the material, which causes dust to become easily suspended in the air. Conversely, porous pavements, which have air gaps in their surface layers, showed reduced dust suspension despite a higher dust load, due to the ability of these voids to trap dust and minimize air-pumping effects from tire–road contact. The study found that a macrotexture depth (MTD) exceeding 1.7 mm stabilized dust concentration, while higher surface wavelengths and silt load (sL) values above 0.1 g/m² significantly contributed to dust suspension. These findings suggest that optimizing road surface texture and aggregate size, considering the voids and depth, can help reduce suspended dust, providing a balance between road safety and environmental management. This research offers valuable insights for designing pavements that mitigate air pollution while maintaining functional performance. Full article

An enhanced chaotic particle swarm optimization fuzzy PID is introduced to address the hydraulic wind turbine grid-connected speed control conditions. In the enhanced algorithm, a Circle chaotic mapping is combined with particle swarm optimization (PSO) to prevent PSO from becoming trapped in local optima. Moreover, a linear inertia weight reduction strategy is integrated to harmonize the algorithm’s capacity for expansive exploration and meticulous exploitation. Then, the enhanced algorithm is utilized to adjust and perfect the configuration variables within the fuzzy PID system. Based on the optimization, speed characteristics of the variable motor are analyzed. Simulation results show that when the swash plate angle factor varies within a specific range, the variable motor speed is only related to the quantitative pump speed. When the input speed of the quantitative pump changes in a step from 400 to 500 r/min, the enhanced CPSO fuzzy PID control approach reduces ascension time by 40% and 76%, and settling time by 80% and 76%, compared to the fuzzy PID and PSO fuzzy PID control approaches, respectively. When the input speed changes in a step from 500 to 600 r/min, the approach reduces ascension time by 25% and 72%, and settling time by 80% and 72%, respectively. When the input speed varies within a range of 400–500 r/min, the approach reduces ascension time by 37.5% and 80%, and settling time by 83% and 80%, respectively. And the enhanced CPSO fuzzy PID speed-control system exhibits no overshoot. Therefore, the enhanced CPSO fuzzy PID algorithm enhances the quantitative pump-motor system’s stability and rapidity, meeting hydraulic wind turbine grid-connected speed-control needs. Full article

Phase transformations induced by short optical pulses are mainstream in studies on the dynamics of cooperative electronic states. We present a semiphenomenological modeling of spatiotemporal effects expected when optical excitons are intricate with the order parameter such as in, e.g., organic compounds with neutral-ionic ferroelectric phase transitions. A conceptual complication appears here, where both the excitation and the ground state ordering are built from the intermolecular electronic transfer. To describe both thermodynamic and dynamic effects on the same root, we adopt, for the phase transition, a view of the excitonic insulator—a hypothetical phase of a semiconductor that appears if the exciton energy becomes negative. After the initial pumping pulse, a quasi-condensate of excitons can appear as a macroscopic quantum state that then evolves, while interacting with other degrees of freedom which are prone to an instability. The self-trapping of excitons enhances their density, which can locally surpass a critical value to trigger the phase transformation. The system is stratified in domains that evolve through dynamical phase transitions and may persist even after the initiating excitons have recombined. Full article

Non-Newtonian fluids are widespread in industry, e.g., biomedical, food, and oil and gas, and their rheology plays a fundamental role in choosing the processing parameters. Centrifugal pumps are widely employed to ensure the displacement of a huge amount of fluids due to their robustness and reliability. Since the pump performance is usually provided by manufacturers only for water, the selection of a proper pump to handle non-Newtonian fluids may prove very tricky. On-field experiences in pump operations with non-Newtonian slurries report severe head and efficiency drops, especially in part-load operations, whose causes are still not fully understood. Several models are found in the literature to predict the performance of centrifugal pumps with this type of fluids, but a lack of reliability and generality emerges. In this work, an extensive experimental campaign is carried out with an on-purpose test bench to investigate the effect of non-Newtonian shear-thinning fluids on the performance of a small commercial centrifugal pump. A dedicated experimental campaign is conducted to study the causes of performance drops. The results allow to establish a relationship between head and efficiency drops with solid content in the mixture. Sudden performance drops and unstable operating points are detected in part-load operations and the most severe drops are detected with the higher kaolin content in the mixture. Performance drop investigation allows to ascribe performance drop to gas-locking phenomena. Finally, a critical analysis is proposed to relate the resulting performance with both fluids’ rheology and the gas fraction trapped in the fluid. The results here presented can be useful for future numerical validation and predicting performance models. Full article

Pumped storage power stations not only serve as a special power load but also store excess electricity from the power system, significantly reducing the curtailment of wind and solar power. This dual function ensures the stable operation of the power grid and enhances its economic benefits. The scheduling optimization problem of a combined wind–solar–pumped storage system is addressed in this study, and an optimization scheduling model is proposed with the objective of maximizing total system revenue. The model is designed to comprehensively account for the generation revenues from wind power, photovoltaic power, thermal power, and pumped storage, as well as the penalty costs associated with pollutant emissions. To address the limitations of traditional algorithms, which are prone to being trapped in local optima and exhibit slow convergence, an improved bat algorithm was developed. The algorithm is enhanced through the use of chaotic mapping to expand the initial solution space, the incorporation of adaptive step-size updates to improve convergence efficiency, and the integration of the Cauchy function to strengthen global search capabilities, thereby effectively avoiding local optima. Simulation results have demonstrated that the improved algorithm achieves significant improvements over traditional bat algorithms and particle swarm optimization (PSO) in terms of optimization efficiency, with total revenue increases of 21.9% and 24.6%, respectively. The optimized scheduling plan is shown to fully utilize the flexible regulation capabilities of pumped storage, mitigating the adverse effects of wind and photovoltaic output fluctuations on grid operations and achieving a balanced trade-off between economic and environmental objectives. Full article

External gear pumps with an involute tooth profile are used in many applications because of their simple shape, low production cost, and excellent reliability. However, they can be characterized by the generation of vibration and noise, due to the pressure pulsation caused by the trapped volume resulting from the gear meshing. In this study, a one-point continuous contact helical gear pump with circular-involute teeth was designed to eliminate the trapped volume. A novel geometrical approach is described to analyze the kinematic flow of this pump. The morphology of the tooth space, which changes depending on the angular position of the rotating gear, is explained by a newly defined algorithm. Algorithms designed for the geometric approach are simple because they define tooth space morphology for specific angular positions and therefore do not require corrections. The area of tooth space calculated through numerical analysis is used to calculate the instantaneous theoretical flow rate. The kinematic flow rate of the numerically analyzed pump can quantify the compressibility effect of the fluid. In addition, the calculated instantaneous theoretical flow rate accurately reflects the physical characteristics compared to previous studies and can be used to identify the cause of flow ripple. Full article

The utilization of atomic or molecular spectroscopy for frequency locking of single-frequency laser to improve laser frequency stability plays an important role in the experimental investigation of optically pumped atomic magnetometers, atomic clocks, laser cooling and trapping of atoms, etc. We have experimentally demonstrated a technique for frequency stabilization of a single-frequency laser employing the bright state spectroscopy (BSS) with a rubidium atomic vapor cell. By utilizing the counter-propagating dual-frequency 795 nm laser beams with mutually orthogonal linear polarization and a frequency difference of 6.834 GHz, which is equal to the hyperfine splitting of rubidium-87 ground state 5$S_{1/2}$, an absorption-enhanced signal with narrow linewidth at the center of Doppler-broadened transmission spectroscopy is observed when continuous scanning the laser frequency over rubidium-87 D1 transition. This is the so-called BSS. Amplitude of the absorption-enhanced signal in the BSS is much larger compared with the conventional saturation absorption spectroscopy (SAS). The relationship between linewidth and amplitude of the BSS signal and laser beam intensity has been investigated. This high-contrast absorption-enhanced BSS signal has been employed for the laser frequency stabilization. The experimental results show that the frequency stability is $4.4\times {10}^{-11}$ with an integration time of 40 s, near one order of magnitude better than that for using the SAS. Full article

Exciton–polaritons, which are bosonic quasiparticles with an extremely low mass, play a key role in understanding macroscopic quantum effects related to Bose–Einstein condensation (BEC) in solid-state systems. The study of trapped polaritons in a potential well provides an ideal platform for manipulating polariton condensates, enabling polariton lasing with specific formation in k-space. Here, we realize quantized microcavity polariton lasing in simple harmonic oscillator (SHO) states based on spatial localized excitons in InGaN/GaN quantum wells (QWs). Benefiting from the high exciton binding energy (90 meV) and large oscillator strength of the localized exciton, room-temperature (RT) polaritons with large Rabi splitting (61 meV) are obtained in a strongly coupled microcavity. The manipulation of polariton condensates is performed through a parabolic potential well created by optical pump control. Under the confinement situation, trapped polaritons are controlled to be distributed in the selected quantized energy sublevels of the SHO state. The maximum energy spacing of 11.3 meV is observed in the SHO sublevels, indicating the robust polariton trapping of the parabolic potential well. Coherent quantized polariton lasing is achieved in the ground state of the SHO state and the coherence property of the lasing is analyzed through the measurements of spatial interference patterns and g⁽²⁾(τ). Our results offer a feasible route to explore the manipulation of macroscopic quantum coherent states and to fabricate novel polariton devices towards room-temperature operations. Full article

This study examines the behavior of single-walled carbon nanotubes (SWCNTs) suspended in a water-based ionic solution, driven by the combined mechanisms of electroosmosis and peristalsis through ciliated media. The inclusion of nanoparticles in ionic fluid expands the range of potential applications and allows for the tailoring of properties to suit specific needs. This interaction between ionic fluids and nanomaterials results in advancements in various fields, including energy storage, electronics, biomedical engineering, and environmental remediation. The analysis investigates the influence of a transverse magnetic field, thermal radiation, and mixed convection acting on the channel walls. The novel physical outcomes include enhanced propulsion efficiency due to SWCNTs, understanding the influence of thermal radiation on fluid behavior and heat exchange, elucidation of the interactions between SWCNTs and the nanofluid, and recognizing implications for microfluidics and biomedical engineering. The Poisson–Boltzmann ionic distribution is linearized using the modified Debye–Hückel approximation. By employing real-world approximations, the governing equations are simplified using long-wavelength and low-Reynolds-number approximation. Conducting sensitivity analyses or exploring the impact of higher-order corrections on the model’s predictions in recent literature might alter the results significantly. This acknowledges the complexities of the modeling process and sets the groundwork for further enhancement and investigation. The resulting nonlinear system of equations is solved through regular perturbation techniques, and graphical representations showcase the variation in significant physical parameters. This study also discusses pumping and trapping phenomena in the context of relevant parameters. Full article

A gear pump is a key rotary-displacement pump for aircraft fuel transportation in the aerospace industry. Due to the great ratio of power-to-weight condition demanded for gear pumps in aircraft fuel transportation systems, the parameter of the rotation speed is a matter of extreme concern affecting internal flow characteristics that determines the adverse effects of cavitation, fuel trapping, and vibration. However, the flow characteristics of an aircraft fuel gear pump influenced by the rotation speed have not been elaborated upon on yet. In this research, the flow characteristics of an aircraft fuel gear pump were studied by considering the influence of the rotation speed. An experiment for testing the external performance of an aircraft fuel gear pump was performed, and a corresponding numerical simulation of a gas–liquid two-phase flow was employed. Distributions of the velocity and pressure at the central cross-sections and their monitored transient developments were comparatively analyzed for different rotation speeds. It was found that a greater pressure oscillational amplitude accompanied by a higher frequency could be induced by a higher rotation speed, especially in the region of gear engagement. Additionally, cavitation evolution characteristics affected by the rotation speed in the fuel gear pump were discussed. The mechanism of cavitation generation in the region of gear engagement to withdrawal was revealed to be the quick release of a great amount of pressure. Furthermore, a dimensionless cavitation area was employed to quantify the periodic cavitation evolution, and the natural exponential development of the maximum dimensionless cavitation area with the rotation speed was determined through curve fitting. This study should be helpful for creating a deeper understanding of the internal flow characteristics of an aircraft fuel gear pump in scientific research and the external performance in aerospace industrial applications. Full article

The advantages of continuous freeze-drying are increasingly being emphasized, including energy saving, high production efficiency, and superior quality. In this context, an innovative continuous production process and cold trap structure for large-scale freeze-drying equipment is proposed. Built-in alternating cold traps are adopted instead of the stationary type to reduce the defrosting downtime, significantly improving the energy efficiency of the refrigeration and heat pump heating units. In the freeze-drying production of shiitake, comparisons between the built-in alternating cold traps and the stationary type indicate a reduction in energy consumption of approximately 24% for the full production process when the alternating cold traps with tube coils are used, that is, from 1937 kW·h for the stationary type to 1471 kW·h. In addition, the energy consumption for the built-in alternating cold traps with finned tube coils could be further reduced by about 8%. Finally, through the implementation of the new continuous production process and built-in alternating cold traps in industrial large-scale freeze-drying equipment, the systematic energy consumption per unit of food dehydration (kg) is reduced by approximately 40%, i.e., from 1.31 kW·h in the intermittent production process to 0.79 kW·h in the new continuous production process. Full article

Wastewater treatment plants (WWTPs) are critical infrastructures for wastewater management, and their durability is crucial. Due to their excellent water tightness and strength, cementitious materials are used to build WWTPs. However, the performance of these materials is affected by aggressive environments. There are few in situ experiments in the literature regarding the deterioration of cementitious materials in WWTPs. This paper investigates their deterioration mechanisms in a sewage pumping station and a sand-trap structure of a WWTP. In situ experiment was conducted by exposing cement specimens in both locations for 1, 2, 3 and 7 months. The physical and morphological changes of the specimens were examined using stereo microscopy and scanning electron microscopy, whereas the mineralogical/solid phase changes were examined using X-ray diffraction. The results showed that the specimens from the pumping station formed colored surface products, which were confirmed to be secondary minerals (i.e., gypsum and ettringite), whereas there were no colored surface products in the sand-trap structure. The results demonstrated that cementitious materials subjected to wastewater vapors (in a pumping station) had higher deterioration effects than those subjected to wastewater liquid (in a sand-trap structure), suggesting that the wastewater vapors are more aggressive toward cementitious materials than wastewater liquids. Full article

Utricularia (bladderworts) are carnivorous plants. They produce small hollow vesicles, which function as suction traps that work underwater and capture fine organisms. Inside the traps, there are numerous glandular trichomes (quadrifids), which take part in the secretion of digestive enzymes, the resorption of released nutrients, and likely the pumping out of water. Due to the extreme specialization of quadrifids, they are an interesting model for studying the cell walls. This aim of the study was to fill in the gap in the literature concerning the immunocytochemistry of quadrifids in the major cell wall polysaccharides and glycoproteins. To do this, the localization of the cell wall components in the quadrifids was performed using whole-mount immunolabeled Utricularia traps. It was observed that only parts (arms) of the terminal cells had enough discontinuous cuticle to be permeable to antibodies. There were different patterns of the cell wall components in the arms of the terminal cells of the quadrifids. The cell walls of the arms were especially rich in low-methyl-esterified homogalacturonan. Moreover, various arabinogalactan proteins also occurred. Cell walls in glandular cells of quadrifids were rich in low-methyl-esterified homogalacturonan; in contrast, in the aquatic carnivorous plant Aldrovanda vesiculosa, cell walls in the glandular cells of digestive glands were poor in low-methyl-esterified homogalacturonan. Arabinogalactan proteins were found in the cell walls of trap gland cells in all studied carnivorous plants: Utricularia, and members of Droseraceae and Drosophyllaceae. Full article