Valley Value Research Articles

Quantitative electroencephalography predicts postoperative delirium in adult cardiac surgical patients from a prospective observational study

The diagnostic and prognostic value of quantitative electroencephalogram (qEEG) in the the onset of postoperative delirium (POD) remains an area of inquiry. We aim to determine whether qEEG could assist in the diagnosis of early POD in cardiac surgery patients. We prospectively studied a cohort of cardiac surgery patients undergoing qEEG for evaluation of altered mental status. Delirium was assessed with the Confusion Assessment Method for the intensive care unit (CAM-ICU). The qEEG were interpreted by clinician, and reports were reviewed to identify features such as amplitude-integrated EEG (aEEG), relative band energy in ɑ/β/θ/δ frequencies, α variability and spectral entropy. The raw EEG was also preprocessed offline for nonlinear analysis including Multi-scale Entropy analysis (MSE) and Detrended Fluctuation Analysis (DFA). Linear regression was performed to quantify associations among EEG findings, delirium, and clinical outcomes. Receiver operating characteristic (ROC) analysis was used to assess the accuracy of the qEEG as POD prediction index. Meanwhile, a comprehensive comparison of dynamic complexity across time scales and DFA exponent α was conducted between the non-delirium and delirium groups. Among those recruited initially (n = 64), 60 patients were evaluated and 29 patients (48.3%) met delirium criteria. When comparing delirious and non-delirious participants, significant differences were found in terms of age (p = 0.03), APACHE II scores (p = 0.004), lactate (p = 0.03), and hospital days (p = 0.048). Multivariate regression analysis revealed that the first quartile (Q1) and fourth quartile (Q4) of peak or valley value of F3-P3/F4-P4 derivation (for example, Q1 of peak value for F3-P3 derivation: OR 12.4, 95% CI 1.72–89.76, p = 0.012) showed a higher association with the incidence of POD. ROC analysis demonstrated qEEG could predict POD with high sensitivity and specificity, yielding an overall good accuracy. For instance, the peak value of F3-P3 derivation (the area under the curve of 0.81), as a predictor of POD showed a sensitivity of 90% and specificity pf 72% (p < 0.001). Furthermore, the MSE curves indicated that the non-delirium group exhibited higher complexity values at fine scales, while the delirium group had significantly higher complexity at coarse scales. The DFA comparison results revealed that long-term fractal exponent alpha2 values were higher in delirium patients than in non-delirium patients, with significant differences observed at the F4-P4 electrodes (p = 0.04). The qEEG can reliably predict delirium after heart cardiac surgery. It is helpful for clinicians to early diagnose and manage these patients.Trial registration: Clinical Trials.gov Identifier, NCT03351985. Registered 1 December 2017.

Fano resonance and exceptional point enhanced sensing in a grating coupled heterostructure

Fano resonance line shape performs ultrasensitive sensing characteristics as its ultrahigh quality factor. Here, we theoretically investigate the sensitivity and figure of merit (FOM) of a novel, to our knowledge, multilayered heterostructure as a sensor. The heterostructure is non-Hermitian and composed of one layer of gold grating, multilayer polyethylene, and polymethyl methacrylate. The rigorous coupled wave analysis method (RCWA) is used to investigate the reflection characteristics of the structure. Interference between the “dark mode,” excited by the grating, and the “bright mode,” excited by the central layers, produces Fano resonance in the forward reflection spectra. Adjustment on the structure parameters can reduce the valley value of the Fano peak to zero, giving rise to scattering exceptional points (EPs). At the wavelength of the EP, the ambient temperature and mechanical stress fluctuations will lift the reflection, available for sensing signal. The sensitivity is higher than that of the structure without Fano peaks and EPs. Moreover, we use the spectral shift for refractive index sensing with a FOM exceeding 200RIU−1.

Simulation of homogenization behavior of compacted bentonite containing technological voids using modified penalty-based contact model

Low-density zones generated during the bentonite blocks/voids homogenization process in the repository may serve as potentially preferential paths for radionuclide leakage. More importantly, void closure during homogenization process involves complex contact problems, where the stiffness at the contact interface typically undergoes significant fluctuations. In this work, with contact interface stiffness addressed through a step function approach, a modified penal.ty-based contact model was proposed to simulate the contact behavior involved at the gap closure stage of the bentonite/gap assemblage homogenization process. Then, unsaturated infiltration swelling tests on bentonite block (1.7 Mg/m3)/gap (width: 2 mm) assemblages were performed, and the variation of dry density at different hydrated times (0, 24, 72, 168, and 720 h) in specific areas were measured. Based on the results, time-dependent swelling pressure profiles of the assemblage were acquired, while the homogenization process was evaluated. Results reveal that after approximately 40 h of hydration, the gap is completely closed, and the radial stress condition of the compacted bentonite transits progressively from the initial free swelling into a constant volume expansion state. The swelling pressure correspondingly develops quickly to a peak value at 1.8 MPa once the hydration starts, then decreases to a valley value of 1.4 MPa at the complete gap closure, and subsequently begins to increase to the final stable value of 1.8 MPa. Further examination reveals that as hydration advances, dry density of the assemblage converges to the expected final dry density with a maximum residual inhomogeneity of about 2 %. Finally, validations demonstrate that the proposed model can accurately reproduce deformations of the assemblage during the free swelling stage, and the swelling pressure profiles. A comparative analysis was made with the previous approach of identifying gaps as highly deformable materials, revealing that the proposed model overcomes the traditional limitations associated with the separation or penetration behavior occurring between the compacted bentonite and contact boundaries during the gap closure.

Isobaric compressed air energy storage system: Water compensating cycle or CO2 compensating cycle?

Isobaric operation of air storage can remove the throttling losses existing in isochoric reservoir, making full use of the storage volume and lowering system construction cost. The water cycle and CO2 cycle are two of the most commonly configurations to stabilize the pressure in the air storage unit. The choice between the two cycles depends on whether the technical complexity and costs are justified by performance gains. This paper mainly focuses on developing the MAP design, a kindly selection diagram plotting the better value of performance indicators between the two systems, to determine the more favorable compensating cycle in the constant storage operation of the compressed air. The analysis results indicate that higher air storage pressure increases the system efficiency. The levelized cost of storage is provided with a valley value when the air storage pressure is at 6.6 MPa for the CO2 cycle and 14 MPa for the water cycle. The optimized systems can share a comparative efficiency of 68.04 % and 68.07 %, and the levelized cost of storage is 0.8237 ¥/kWh for the CO2 cycle and 0.7869 ¥/kWh for the water cycle. The water is suggested to be the compensating fluid for the isobaric system when the water machine efficiency is higher than 0.85 or else opting for CO2 proves to be a more economically viable choice.

Variations of the residual magnetic fields of X70 pipeline steels with double defects

The aim of this research is to correlate residual magnetic fields (RMFs) with double defects in ferromagnetic steels. Specimens of X70 pipeline steels were machined into smooth plates with two types of defect (single and double defects) for comparison. Tensile tests were carried out to detect the RMF signals on the surface of the defective specimens. The variation of the tangential component of the RMF signals was presented and magnetic parameters were defined to investigate the abnormal magnetic changes of the two types of defect. It was found that the peak value of the tangential component was not influenced by defect types and the valley value was capable of evaluating the interaction effect between defects. Correlation between the RMF signals and the location of double defects was also investigated. This research will promote the investigation of defect clusters in ferromagnetic steels based on the metal magnetic memory (MMM) technique.

Surface Evolution and Optimizing Strategy for Polishing Natural Heterogeneous Marble Using Sol-Gel Diamond Pad

Inefficiency and poor quality are the main problems in polishing natural heterogeneous marbles using sol-gel (SG) diamond pads. A strategy was proposed to address these issues by establishing a natural heterogeneous marble polishing model based on the optimal polishing time. The surface evolution and optimal time for polishing natural heterogeneous marble were systematically investigated. Six different types of marbles were polished by the sol-gel diamond pads. The surface glossiness, roughness, peak–valley value, and surface morphology of the marbles were measured and analyzed after different polishing times. The optimal polishing time for each marble was revealed using sol-gel diamond pads. The experimental results show that the standard deviation of the hardness distribution of marble tile significantly affects the material removal inconsistency and evolution of the surface during polishing, resulting in different optimal polishing times for different kinds of marble. The larger the standard deviation of the hardness of the marble is, the more difficult it is to obtain better surface quality, and the orange peel effect is more likely to occur. Furthermore, the optimal polishing time has a good logarithmic relationship with the standard deviation of the hardness distribution. Finally, a curve model of the optimal polishing time for each marble was established. The determination of the optimal polishing time can effectively optimize the polishing process, simplify the processing flow, improve production efficiency, and reduce production costs. The proposed method and obtained results in this paper can provide a theoretical basis and reference for polishing other types of heterogeneous stone materials.

Multi-stopband filter based on frequency selective surface

This paper presents the design of a terahertz multi-stopband filter based on a metasurface structure which consisting of multiple metallic strips. By adjusting the dimensions and arrangement of these metallic strips placed on a dielectric substrate, the precise control of the filter performance is achieved. This structure exploits the electromagnetic resonances of metallic strips at terahertz frequencies to generate stopbands, thereby enabling selective filtering. Numerical studies demonstrates that these configurations can produce multiple stopbands within the 4.2 to 15.5 THz frequency range, with tunable center frequencies and bandwidths. Through the research of the transverse and longitudinal filter model structure, the band-stop filter with more stopbands can be realized, and the transmission valley value is kept within 5 %, which is crucial for enhancing filter performance. Moreover, the study reveals that tuning the dimensions of the metallic strips can modulate the resonances, resulting in a redshift of the filter's central frequency and an expansion of the passband width. These findings provide a new method for the performance improvement of terahertz filters, advanced filtering technology and electromagnetic wave control technology.

Experimental Study on Temperatures of Water Walls in a 1000 MW Ultra-Supercritical Boiler under the Condition of Flexible Peak Regulation

To meet the Chinese government’s energy-saving and emission-reduction policies, flexible peak regulation is necessary for traditional coal-fired boilers. Flexible peaking leads to large changes in boiler load, which affects the safety of the boiler water wall. In this paper, a 1000 MW ultra-supercritical unit was tracked for three years, and effective data were selected to study the temperature characteristics of the water wall under flexible peak regulation. The results show that the lower the load, the greater the temperature fluctuation of the water wall. The temperature distribution of the spiral water wall is more uniform. The position of the temperature valley value of the rear spiral water wall was found, and the load of more even temperature distribution was also found. The temperature change of the front vertical water wall was the most complex of all the water walls. The 643.9 MW load case showed different behavior to the temperature distribution of the water wall. The side water walls were heated evenly under the different loads. The characteristics of the temperature distribution of the side vertical water wall were found through statistical analysis. The fitting equation for the change rule of the temperature is presented. The higher the load, the better the equations. Finally, this paper gives some advice on how to avoid temperature deviation in the water wall, and the detailed research highlights the safe running of water walls.

Effects of chemical solution components on the contact angle of typical minerals in soil: quartz, orthoclase and plagioclase

Different chemical solutions can significantly change the contact angle (CA) of soil, but few studies have studied the change rule and action mechanism of the CA from the mineral composition of soil essence. In unsaturated soil mechanics, the CA is an important parameter to calculate the wet suction between soil particles in unsaturated soil. When the chemical composition of the soil pore liquid changes, the CA will also change, which will affect the wet suction and other parameters, thus changing the macroscopic mechanical properties of the soil. In this study, the CA of air-solution-mineral phases with different solution components (pH, type and concentration of salt solution) of different minerals (quartz, orthoclase and plagioclase) were measured. The results show that the CAs of quartz, orthoclase and plagioclase all rise first and then drop with the rise of pH. The peak CAs are pH = 5, pH = 4 and pH = 3, respectively. Quartz, orthoclase and plagioclase all have valley values in different concentrations of NaCl and KCl solutions. In CaCl2 solution, only quartz has valley value, while orthoclase and plagioclase increase monotonously. Quartz in soil plays a main role in the influence of soil CA, followed by orthoclase and plagioclase. The CA of different minerals in different chemical solutions is mainly controlled by electric double layer interaction and functional groups interaction. In different salt solution environment, in addition to the above two effects, the mineral CA is also affected by the surface tension.

Prediction of simultaneous enhancement of Goos-Hänchen shift and reflectance in VO2 grating structure

Vanadium dioxide (VO2) material stands out in the family of the phase change materials due to its temperature-dependent phase transition properties, which make it a promising candidate for the temperature-dependent optoelectronic devices. Enhancement of the Goos-Hänchen (GH) shift is essential in VO2-based nanostructures for their applications, but it has been limited to the multilayered structures with VO2 materials so far. Here, we theoretically investigate the GH shift and corresponding reflectance in the VO2-based grating structure. We evidence that this structure has two GH peaks (3107λ and 2266λ) and high reflectance values (both up to 1) when VO2 is in the insulating phase as well as the maximum GH valley (−1061λ) and low reflectance (0.19) when VO2 is in the metallic phase. The electromagnetic field distributions in this hybrid structure suggest that the guided mode resonances (GMRs) can be excited no matter whether VO2 is in its insulating or metallic phases due to the couplings between the incident waves and the adjacent evanescent diffracted order waves, which produces their enhanced GH shifts. Different from the former case with the high reflectances and the large GH shifts, the latter has the low maximum magnetic field intensity due to the lossy property of the metallic VO2, which leads to the low reflectance and small GH valley value. Additionally, we have also found that by the alterations of the temperature-dependent conductivity of VO2 and the geometric parameters of the structure allows for the control the magnitude and position of the GH peak or valley. The simultaneously enhanced GH shifts and reflectances in the VO2-based grating structure, associated with its controllable features, enable it an effective configuration for establishing the temperature sensors and optoelectronic switches.

Long-term mulched drip irrigation facilitates soil organic carbon stabilization and the dominance of microbial stochastic assembly processes

Mulched drip irrigation (MDI) is generally accepted as a method to decrease soil salinization and improve crop yields in arid and semi-arid regions. However, there remain gaps in how MDI drives soil organic carbon (SOC) dynamic microbial assembly processes with time, and the mediating role of microorganisms remains unclear. In this study, we investigated the aforementioned issues across soil profiles in cotton fields with different years of MDI. The results showed that MDI did not cause the differences in SOC, particular organic carbon (POC), and mineral-associated organic carbon (MOC) in soil layers. The POC and MOC contents had a parabola relationship with time, and showed an opposite trend in soil. After 15 years of MDI, the ratio of MOC/SOC increased to a peak value of 50 % and 52 % in topsoil and subsoil, respectively; the ratio of POC/SOC decreased to valley values of 50 % and 48 %, respectively (P < 0.05). Long-term MDI reduced the differences in oxidase between soil layers but accelerated SOC loss by increasing polyphenol oxidase activity (P < 0.05). Compared with that of other years, with 10 years of MDI, bacterial Shannon diversity decreased to a valley value, and fungal Shannon diversity reached to a top value in subsoil (P < 0.05). In general, stochastic processes were mainly controlled by dispersal limitation, and undominated processes dominated microbial assembly; however, there was a close relationship between bacterial communities and organic carbon fractions. The high percentage of positive linkages among microorganisms indicated that long-term MDI was beneficial for carbon fixation. Additionally, a decrease of fungal oligotroph/copiotroph ratio, the relative abundance of Ascomycota and Basidiomycota was beneficial for the accumulation of SOC and POC in topsoil (P < 0.05). In conclusion, long-term MDI is useful for the fixation of organic carbon via improving soil POC content and strengthening linkages within community assemblies.

Diurnal Variation in Summer Precipitation and the Characteristics of Precipitation Events in the Western Tarim Basin, China

The Tarim Basin in the western part of Northwest China (NWC) is the largest inland basin in the world and one of the most arid regions in the middle latitudes. In recent years, heavy precipitation events have occurred frequently in this region, especially in the western Tarim Basin (WTB), due to the climate change. Based on the hourly precipitation data from 2010 to 2022, the diurnal variation in summer precipitation and the characteristics of precipitation events with different durations in WTB have been analyzed. The results mainly show that (1) the diurnal variations in the precipitation amount (PA), precipitation frequency (PF) and precipitation intensity (PI) mainly present a unimodal pattern, but the times of maximum value do not coincide. The peak value of PA and PF appears between 01:00 and 03:00 BJT (Beijing Time), while the valley value appears around 18:00 BJT, yet the peak value of PI appears between 20:00 and 23:00 BJT with no obvious valley value. (2) There are some differences in the diurnal variation characteristics of precipitation among different summer months and different regions. (3) During the past decade, the precipitation structure in WTB has been continuously adjusted, and short-duration- and long-duration-precipitation-dominant periods appear alternately. On the whole, short-duration precipitation has been more frequent in summer, accounting for 70% of the total precipitation events and 40% of the total accumulated precipitation amount. These results can help us to better understand the refined physical characteristics of precipitation events and enhance our understanding of the local climate in the WTB under the background of climate change.

Effect of electroacupuncture pre-conditioning on the expression rhythm of core clock gene Bmal1 in uterine tissue of controlled hyperstimulation rats.

To observe the effect of electroacupuncture (EA) pre-conditioning on the expression rhythm of clock gene Bmal1 in the uterine tissue of rats with controlled ovarian hyperstimulation(COH), so as to explore its mechanisms underlying improvement of the endometrial receptivity of ovarian superovulation during implantation. Seventy-two female SD rats with typical estrous cycles were randomly divided into normal control, model and EA pre-conditioning (pre-EA) groups, with 24 rats in each group. The COH model was established by giving the rats with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) by intraperitoneal injection. The rats of the pre-EA group received EA stimulation (1 Hz/5 Hz, a tolerable strength) of "Guanyuan"(CV4) and "Sanyinjiao"(SP6) for 15 min each time, once daily (at 21：00 every day). After successive EA intervention during the first two estrous cycles, the modeling began in the third estrus cycle and the EA intervention was continued till the end of modeling, followed by raising the rats with superovulation induction and male rats undergoing vasoligation in one cage (1∶1). The rats during the estrum in the normal control group or those of the model group at the end of modeling were raised together with the male rats undergoing vasoligation in one cage. On the 5th day (04：00 AM) after raising in one cage, the rats in the three groups were sacrificed in six batches every 4 hours, with 4 rats in each group in each batch. The H.E. staining was used for revealing alterations of the endometrial thickness, number of glands and blood vessels and tissue histology, and ELISA employed to ascertain the contents of estradiol (E2) and progesterone (Pg) in serum. The expression rhythm of core clock gene Bmal1 ［In the present study, Zeitgeber time (ZT) is an artificially set laboratory time, i.e., ZT7 (07：00) is light on and ZT19 (19：00) is light off.］ and the expression of endometrial HoxA10 and leukemia inhibitory factor (LIF) mRNAs were detected by quantitative real-time PCR. The Western blot was employed to detect the expression levels of HoxA10 and LIF proteins. Findings of the clock gene Bmal1 level showed that the expression peak was at ZT12 and the valley value at ZT20 in the normal control group, and that of the peak value was at ZT20 and valley value at ZT12 in the model group, while in the pre-EA group, the peak value was at ZT8, and the valley value at ZT4. The difference of Bmal1 levels among the three groups was most significant at ZT12 (12：00), therefore, the tissue samples were taken at ZT12 in this study for comparison of the levels of different indexes among the 3 groups. Compared with the control group, the endometrial thickness, number of glands and blood vessels, HoxA10 and LIF mRNAs and proteins were significantly down-regulated (P<0.01, P<0.05), and contents of serum E2 and Pg were considerably up-regulated in the model group (P<0.01, P<0.05). Relevant to the model group, the pre-EA group had an apparent increase in the endometrial thickness, number of glands and blood vessels, and expression levels of HoxA10 and LIF mRNAs and proteins (P<0.05, P<0.01), and a marked decrease in the serum Pg (P<0.05). At the ZT12 (12：00 noon), compared with the normal control group, the mRNA level of Bmal1 was significantly decreased in the model group (P<0.01)；and compared with the model group, the level of Bmal1 mRNA was significantly increased in the pre-EA group (P<0.05). In addition, at the node of ZT16, the mRNA level of Bmal1 was significantly decreased in the model group in comparison with the normal control group (P<0.01). EA preconditioning can improve the endometrial receptivity during the implantation window period in rats with COH, which may be related to its functions in regulating the expression of clock gene Bmal1 in the uterine tissue and in correcting the disturbance of clock gene rhythm.

Variation Characteristics and Source Analysis of Atmospheric Ozone Pollution in Guanzhong Region

Guanzhong urban agglomeration has a good development foundation and great development potential, and it has a unique strategic position in the national all-round opening up pattern. In recent years, the problem of near-surface ozone （O3） in the Guanzhong Region has become increasingly prominent, which has become a bottleneck affecting the continuous improvement of air quality. In order to effectively prevent and control O3 pollution, this study analyzed the characteristics of annual, monthly, and daily changes in O3 concentration in the Guanzhong Region based on the environmental monitoring data from 2018 to 2021. A geo-detector was used to study the driving factors of the spatial differentiation of O3 concentration, and the sources of O3 were analyzed using a backward trajectory model and emission inventory construction. The results showed that the daily and monthly variation in O3 concentration in the Guanzhong Region were unimodal. The daily maximum value appeared at 15：00, the minimum value appeared at 07：00, the peak value of the monthly average appeared in June, and the valley value appeared in December. The O3 concentration was highest in summer, followed by that in spring, and the lowest in winter. The days of O3 exceeding the standard showed mainly mild pollution, and moderate and above pollution showed a trend of decreasing first and then increasing. The O3 concentration in the Guanzhong Region was mainly closely related to precursors and meteorological factors, and the explanatory power of the interaction of each factor was significantly greater than that of any single factor. The regional transport of O3 concentration in the Guanzhong Region was mainly affected by easterly airflow, followed by the northwest direction, with the potential source areas located mainly in Henan Province and Hubei Province. The main local sources of volatile organic compounds （VOCs） were solvent use sources, process sources, and mobile sources, and the main emission sources of nitrogen oxides （NOx） were mobile sources and industrial production combustion sources. The research results have a guiding significance for O3 joint prevention and control in the Guanzhong Region.

A novel EPID-based MLC QA method with log files achieving submillimeter accuracy.

The purpose of this study is to develop an electronic portal imaging device-based multi-leaf collimator calibration procedure using log files. Picket fence fields with 2-14mm nominal strip widths were performed and normalized by open field. Normalized pixel intensity profiles along the direction of leaf motion for each leaf pair were taken. Three independent algorithms and an integration method derived from them were developed according to the valley value, valley area, full-width half-maximum (FWHM) of the profile, and the abutment width of the leaf pairs obtained from the log files. Three data processing schemes (Scheme A, Scheme B, and Scheme C) were performed based on different data processing methods. To test the usefulness and robustness of the algorithm, the known leaf position errors along the direction of perpendicular leaf motion via the treatment planning system were introduced in the picket fence field with nominal 5, 8, and 11mm. Algorithm tests were performed every 2weeks over 4 months. According to the log files, about 17.628% and 1.060% of the leaves had position errors beyond ±0.1 and ±0.2mm, respectively. The absolute position errors of the algorithm tests for different data schemes were 0.062±0.067 (Scheme A), 0.041±0.045 (Scheme B), and 0.037±0.043 (Scheme C). The absolute position errors of the algorithms developed by Scheme C were 0.054±0.063 (valley depth method), 0.040±0.038 (valley area method), 0.031±0.031 (FWHM method), and 0.021±0.024 (integrated method). For the efficiency and robustness test of the algorithm, the absolute position errors of the integration method of Scheme C were 0.020±0.024 (5mm), 0.024±0.026 (8mm), and 0.018±0.024 (11mm). Different data processing schemes could affect the accuracy of the developed algorithms. The integration method could integrate the benefits of each algorithm, which improved the level of robustness and accuracy of the algorithm. The integration method can perform multi-leaf collimator (MLC) quality assurance with an accuracy of 0.1mm. This method is simple, effective, robust, quantitative, and can detect a wide range of MLC leaf position errors.

Sound absorption performance and mechanism of aluminum foam with double-layer structures of conventional and porous cell walls

Open-cell aluminum foam exhibits sound absorption valleys in the 2500-4000 Hz range, reducing its sound absorption performance in the 800–6300 Hz range. This paper prepared a novel aluminum foam with a double-layer structure using the infiltration casting method, and its pore structure, sound absorption performance, acoustic model, and sound absorption mechanism are investigated. The double-layer structure consists of a conventional pore (CP) layer with a single pore size of 250 μm or 600 μm and a porous cell wall (PCW) layer with double pore diameters of 250 μm and 600 μm. As the thickness ratio between the CP and PCW layers decreases, the acoustic absorption valley value of the double-layer structure increases when combined with a small-pore CP layer. In contrast, it decreases slightly when combined with a large-pores CP layer. The double-layer structure reaches a sound absorption valley value and average sound absorption coefficient of 0.912 and 0.902, respectively. The double-layer structure's sound absorption valley value is better than that of a homogeneous structure, improving sound absorption performance. A Lu modified model is established to characterize the sound absorption of the double-layer structure, which closely matches the experimental results. The modified model further analyzed the vital geometrical parameters affecting the absorption valleys. Acoustic impedance analysis shows the enhanced sound absorption valleys are due to: 1) Gradient acoustic impedance reduces sound reflections at the air-structure interfaces and increases secondary reflection at the interfaces in the structure; 2) The series–parallel configuration increased the resonance peak bandwidth, while the dual-sized resonance cavities regulated the resonance peak frequency.

Monitoring Spatial–Temporal Variations in River Width in the Aral Sea Basin with Sentinel-2 Imagery

Rivers in arid regions serve as crucial freshwater resources for local communities and play an essential role in global hydrological and biogeochemical cycles. The Aral Sea Basin (ASB) in Central Asia is characterized by an arid climate and river dynamics that are sensitive to climate change and human activities. Monitoring the spatiotemporal variations in river water extent in the ASB is essential to maintain an ecological balance and ensure water security. In this study, we extracted data regarding monthly river water bodies in the ASB from 2017 to 2022 by synthesizing monthly Sentinel-2 images. The water extents on the Sentinel images were automatically mapped using the Otsu method, and the river widths for all river channels were calculated using the RivWidth algorithm. We investigated the relationships between the river dynamics and the geomorphology, climatic change, human activities, and the annual and interannual variations in the river width in different reaches of the basin. The results show a seasonal variability in the river width, with most rivers reaching the largest width in the warm season and a few rivers in the middle and lower areas reaching the valley value in the warm season. Compared to their tributaries, the mainstem in the middle/lower regions showed less seasonal variability. According to interannual analysis, most of the rivers in the ASB significantly narrowed between 2017 and 2022, a phenomenon which is generally impacted by temperature and evapotranspiration variations. Comparisons show that our results provide improved information about the narrow river reaches and denser river networks compared to the previous global dataset, demonstrating the advantageous properties of high spatial resolution in Sentinel-2 imagery.

Biochemical analyses in the ICARDA collection of unique dried materials of lentils

Background: Among conventional grains, lentils stand out as a rich source of nutrients, boasting high levels of protein and low levels of carbohydrates. They serve as an excellent meat alternative and are abundant in macronutrients, micronutrients, and bioactive phytochemicals. The red lentil seed coat surpasses other legumes in phenol content, showcasing remarkable antioxidant activity. Recognized as a high-level functional crop, lentils demonstrate efficacy in mitigating various health issues, including hypertension, cardiovascular disease, diabetes, and cancer. Objective: This study aims to analyze the biochemical and bioactive components, such as proteins and monosaccharides, in selected lentil varieties that thrive in the conditions of the Ararat Valley and hold economic value. The objective is to evaluate their potential as functional foods. Methods: This study was conducted at the Scientific Centre of Vegetables and Industrial Crops in Darakert, Armenia, from 2021 to 2022, and used a block-randomized design with 4 replications. Lentil seeds were planted in mid-May, with proper care and optimal spacing. Harvested in mid-July, lentil fruits underwent biochemical analysis in the laboratory. Investigated lentil varieties included those from ICARDA collection and locally bred ones. Total protein, protein nitrogen, and carbohydrate content were determined using Kjeldahl’s, Bernstein’s, and Ofner's iodometric methods, respectively. Results: The investigation into the biochemical properties of the selected lentil varieties revealed protein levels ranging from 20.5% to 23.9%, non-protein content between 1.2% and 1.6%, and monosaccharides ranging from 6.2% to 6.7%. Conclusions: Economically valuable lentil varieties, both sourced from the ICARDA collection (Flip 2007-12L, Flip 2007-3L, Flip 2007-30L, EP-54, Sell from1767L) and locally bred varieties that are registered in the State Register of Breeding achievements of Armenia (Talini-6, Haykakan88), exhibit high concentrations of key biochemical properties such as proteins, non-proteins, and monosaccharides. When considering their potential as functional foods with various health benefits, these varieties align well with contemporary nutritional trends emphasizing the inclusion of health-promoting ingredients in diets. Further research and development in this area hold the promise of not only expanding the agricultural and culinary landscape in Armenia but also contributing to the broader conversation around nutrition and functional foods around the world. Keywords: lentils, biochemical properties, protein, non-protein, monosaccharides

A Novel Approach to Mapping the Spatial Distribution of Fruit Trees Using Phenological Characteristics

The lack of high-spectral and high-resolution remote sensing data is impeding the differentiation of various fruit tree species that share comparable spectral and spatial features, especially for evergreen broadleaf trees in tropical and subtropical areas. Here, we propose a novel decision tree approach to map the spatial distribution of fruit trees at a 10 m spatial resolution based on the growth stage features extracted from Sentinel-1A (S-1A) time-series synthetic aperture radar (SAR) data. This novel method was applied to map the spatial distribution of fruit trees in Maoming City, which is known for its vast cultivation of fruit trees, such as litchi, citrus, and longan. The results showed that the key to extracting information on the distribution of fruit trees lies in the fact that the fruit ripening and expansion period attenuates the information on the vegetation of fruit trees, a characteristic of the reproductive period. Under VH polarization, different fruit tree growth stage traits were more separable and easier to distinguish. The optimal features, such as Hv (high valley value of the 14 May, 26 May, and 7 June SAR data), Tb (difference between the 7 June and 14 January SAR data), Cr (high valley value of the 13 July, 25 July, and 6 August SAR data), and Lo (high valley value of the 23 September, 17 October, and 11 November SAR data), were constructed based on the optimal window. The thresholds for these features were set to 1, 1, 1.5, and 1, respectively. The classification model can effectively distinguish different fruit trees and extract distribution information with overall accuracy (OA) of 90.34% and a Kappa coefficient of 0.84. The proposed method extracts the spatial distribution information of different fruit trees more accurately and provides a reference for the extraction of more tropical and subtropical species.

Surface heat flux of upward circular water jet impingement on a moving hot steel sheet

This study experimentally investigated the boiling heat transfer characteristics of a circular upward water jet issued from a 7-mm-diameter nozzle impinging on a moving hot 0.3- mm-thick stainless-steel sheet. The moving velocity (1.5, 3.0, and 4.4 m/s), temperature (100–590 °C), and water flow rates (2.5, 3.0, and 3.5 L/min) were varied during the test. The surface heat flux in the jet impact region depended significantly on the initial temperature of the solid. The surface heat flux increases as the solid temperature increases, attains a peak value (∼30 MW/m2) before decreasing, and reaches a valley value before increasing again. Furthermore, the moving velocity of the solid influences the cooling characteristics, considering that the duration of water contact of a local point on the test sheet is shorter for larger velocities. Moreover, the maximum value of the surface heat flux in the jet impact region can be roughly correlated with the local temperature of the solid. The maximum heat flux peaked at approximately 190 °C and reached a valley at approximately 370 °C. Three empirical correlations for predicting the maximum heat flux in the nucleate, transition, and film boiling are built as functions of the local temperature. The equations in the transition and film boiling can predict the results within a ±20 % error margin.