Layering Research Articles

Ex-sulfates in the Atmosphere of Barnaul: Assessment and Sources of Еmission

The methodology for calculating the content of ex-sulfates (sulfates of anthropogenic origin) in the ground layer of the atmosphere for the flat territory of the Altai Territory is substantiated. The assessment was made of the content of ex-sulfates in precipitation falling on the territory of the city of Barnaul, as well as the analysis of the percentage of ex-sulfates in the total volume of sulfates in the surface layer of the city’s atmosphere over the past eight years (2014–2022). A correlation analysis of the weighted average seasonal values of ex-SO42– concentration in precipitation and air temperature was carried out. Their high negative correlation in the cold season of the year is shown. It was noted that no significant relationship was found for the warm period, which indicates a direct dependence of the concentration of ex-sulfates on the volume of coal combustion during the heating season.

Double-formant PCF-SPR refractive index sensor with ultra-high double-peak-shift sensitivity and a wide detection range

A dual-resonance-peak photonic crystal fiber–surface plasmon resonance (PCF-SPR) refractive index (RI) sensor is designed for different wavelength ranges. The first resonance peak of the sensor is distributed in the wavelength range of 700–2350 nm, while the second peak is distributed in the range of 2350–5550 nm. In addition to detecting analytes using the full spectrum of constraint losses (CLs), it is also possible to use a single resonance peak to achieve the detection of analytes. By systematically optimizing the nanowire diameter, the diameter of the inner and outer layer air hole, the width of the groove, the polishing depth, and the distance from the outer layer air hole to the fiber core, the optimal structure of the sensor is finally determined. In this study, the sensor was studied by numerical analysis, and the characteristics of the sensor were evaluated by wavelength detection technology. The results show that within the RI range of 1.24–1.37, the sensor has a maximum wavelength sensitivity (WS) of 54700 nm/RIU for detecting the RI of analytes. Within the above refractive index range, the regression coefficient R2 of the dual-peak-resonance wavelength is 0.99993, ensuring the accuracy of the estimated resonance wavelength of the sensor. In addition, the sensor can also use dual-peak-shift sensitivity (DPSS) to detect the refractive index, which is a relatively new sensing technology. The maximum DPSS of the sensor is 95300 nm/RIU. Due to its high sensitivity and unique dual-peak characteristics, this sensor has wide application prospects in medical diagnosis, environmental monitoring, food safety, and other fields.

Frost crystal growth behavior on a hydrophilic surface over a wide range of cold surface temperature

The initial frosting phenomenon is a discontinuous phase nucleation process, the cold surface temperature and properties have a decisive influence on this phenomenon, especially in the initial frosting stage. With the development of aerospace and energy transportation technology, frost formation at low temperatures (-100 °C∼-30 °C) and ultra-low temperatures (-273 °C∼-100 °C) has gradually attracted the attention of researchers. In this paper, the initial frosting phenomena on hydrophilic surfaces with a contact angle of 10° (CA= 10°) and ordinary (CA= 95°) surfaces are studied experimentally in a wide range of cold surface temperatures (-190 °C∼-30 °C). Four modes are confirmed: cold surface condensation frosting, cold surface sublimation frosting, air boundary layer condensation frosting and air boundary layer sublimation frosting. It is also found that the four frosting modes do not appear in turn with the decrease of the cold surface temperature, but two or more frosting modes appear at the same time. And the surface contact angle has an important influence on the frosting mode. The initial frost crystal morphology mainly depends on the cold surface temperature and the corresponding frosting mode. Four different forms of frost crystals are observed: hexagonal prism (feather), branch (pine needle), cluster (shrub) and floc (grape), in which the cluster frost crystal is more sensitive to the surface contact angle and can appear in different temperature ranges due to different contact angles. Based on the statistics of the size, quantity, and distribution of the initial frost crystals, it is found that -70 °C is a major turning point for frost formation from the cold surface sublimation frosting to the air boundary layer sublimation frosting, and an important change has taken place near this point. Furthermore, it affects the shape and size distribution of frost crystals. These findings are of great significance for the study and understanding of frost crystal growth mechanism in the initial stage of frost formation at low and ultra-low temperatures.

Distribution and Biology of Protaetia fieberi (Coleoptera, Scarabaeidae)-Is Protection Status Required?

Studies on saproxylic species of Coleoptera have garnered significant attention due to the rarity of some of them. To investigate the distribution and biology of Protaetia fieberi (Kraatz, 1880) (Scarabaeidae: Cetoniinae) in European Russia, we analyzed data from 16 regions collected between 2018 and 2024. This species has been reliably recorded in 26 regions. We describe the species' distribution area boundaries and discuss limiting factors that inhibit its spread to the north, south, and southeast of European Russia. The primary limiting factor is the lack of suitable biotopes. Within its distribution, Protaetia fieberi prefers deciduous and mixed forests of various types. These habitats include both old-growth forest ecosystems and secondary forests that have regenerated following logging. The species also inhabits man-made forest ecosystems, such as field protection forest belts, old parks, and gardens. In forest ecosystems, Protaetia fieberi tends to occupy the upper levels and is rarely found on the ground layer. Conversely, in open areas such as glades, the species is more commonly found at ground level. This distribution pattern is linked to the adults' feeding preferences, which include consuming sap on tree trunks in forests and feeding on flowering plants in open ecosystems. The seasonal activity of Protaetia fieberi peaks from the third decade of June to the second decade of July. It is hypothesized that the perceived rarity of Protaetia fieberi in research samples is due to the specific baiting methods used, with beer traps being the most effective. The status of the species is re-evaluated in light of new data, suggesting that Protaetia fieberi is common rather than rare in European Russia.

Surface plasmon polariton excitation and propagation in metal tripod systems

Through the activation of a planar gaseous medium consisting of four-level tripod atoms, our approach provides a mechanism to generate the Surface Plasmon Polariton (SPP). We investigate a three-layer structure in which the bottom layer is composed of atoms arranged in a tripod configuration, a metal film is layered in the middle, and a transparent layer of either air or vacuum resides on top. The bottom layer facilitates SPP excitation via amplification in the atom arrangement, caused by three laser beams: control, weak probe, and signal. The electromagnetically induced transparency effect, which can be seen in atoms, compensates for the momentum difference between light and SPP. We can coherently change SPP propagation length by altering control field strength, resonance, and off-resonant detuning. SPP optical gain power, propagation length, penetration depth, and metal thickness effects are also examined. Our method to generate SPPs may find use in lithography, sensors, polarizers, along with photodetectors.

Impact of pressure and temperature on the hydration resistance of rice

Crop soaking, a hydration process driven by diffusion, is essential for applications such as milling and germination. This study investigated the moisture absorption of rice kernels during soaking, considering factors like pressure and temperature. The experimental data were analyzed using the Peleg model to understand hydration kinetics, revealing a strong correlation between empirical and regression data, with determination coefficients mostly exceeding 0.99. The study also assessed soaking hydration resistance, identifying contributions from various rice layers, including the husk and bran. Moisture content increased gradually with soaking time, with higher temperatures enhancing absorption. Under normal pressure, white rice absorbed water faster than paddy and brown rice, with brown rice exhibiting higher hydration resistance. Interestingly, paddy rice soaked faster than brown rice under certain conditions due to the air layer between husk and bran, which was eliminated under vacuum or higher temperatures, though the water replacing the air remained unabsorbed. This study aggregated hydration resistance from each kernel to determine layer resistance and specific diffusivity of husk and bran.

Stable Air Retention under Water on Artificial Salvinia Surfaces Enabled by the Air Spring Effect: The Importance of Geometrical and Surface‐Energy Barriers, and of the Air Spring Height

AbstractSuperhydrophobic surfaces that can remain dry under water have a high potential as nontoxic antifouling coatings or for drag‐reducing ship coatings. The Salvinia effect leads to impressive stable air layers on underwater submerged floating plants Salvinia, decisively determined by the hydrophilic tips of the otherwise hydrophobic Salvinia hairs (Salvinia paradox). The water adheres to these hydrophilic tips, stabilizing the water–air interface. An even more important contribution to the stability of the air layer is provided by the air spring, which is formed by the air volume bound by the hydrophilic leaf edge and the leaf base. Using an artificial Salvinia model with hydrophobic pillars (syn‐trichomes), how the stability against pressure changes in water depends on the height of the artificial hair is systematically shown: a reduction of the air spring height from 3 mm to 300 µm increases the stability against negative pressure by 500% from 72 to 380 mbar. Thicker air layers react much more strongly when subjected to overpressure (1000 mbar). It is also shown that the presence of a boundary is essential for the function of the air spring: removing the limiting hydrophilic edge around the hydrophobic air spring reduces the stability against negative pressure by 300%.

Soil Carbon and Nitrogen Stocks Across Hillslopes Underlain by Continuous Permafrost in the Northern Arctic Foothills, Alaska, United States

ABSTRACTConstraining the variability of soil organic carbon (SOC) and total nitrogen (TN) stocks across hillslopes in Low Arctic permafrost‐affected landscapes remains a significant challenge for improving global estimates of permafrost SOC stocks. We investigated SOC and TN stocks across hillslopes at two sites in the Arctic Foothills of Alaska, United States (Happy Valley and Sagwon Hills). Average SOC and TN stocks for the 0–1‐m depth interval were high (52.0 ± 15.1 kg C m−2 and 2.74 ± 0.82 kg N m−2) and linearly related (R2 = 0.74, p < 0.0001). Unlike soils of other permafrost and nonpermafrost landscapes, variability was greatest within rather than between hillslope positions. Furthermore, SOC and TN stocks in the surface 1 m did not exhibit strong patterns by hillslope position and were only weakly associated with major geomorphic parameters that typically predict SOC and TN stocks well in other landscapes. Although sampling at upper hillslope positions was largely limited to depths of less than 1.5 m due to the presence of coarse fragments in reworked glacial till, deeper observations at lower hillslope positions (footslopes, toeslopes, and basins) revealed significantly larger SOC stocks (92.0 ± 18.0 kg C m−2 at 2 m; 117.1 ± 10.4 kg C m−2 at 3 m). The unique small‐scale variability in ice content, cryoturbation, patterned ground, and organic layer thickness on these broad, Low Arctic sites contributes to the relatively homogeneous distribution of SOC and TN stocks across hillslope positions in the top 1 m, but a future focus on deeper sampling may reveal greater differences in SOC and TN stocks.

Simulation Analysis of Influence Laws of Sound Barrier Acoustic Performance When Using Ceramic as Sound-absorbing Materials

Abstract The excellent sound absorption performance of Sound Barrier which using Ceramic as Sound-absorbing Materials can be attributed to their corrosion resistance, lightweight nature, small particle size, and internal microporous structure. As a result, the application of new ceramic-based sound absorption materials in sound barriers is becoming increasingly widespread. To address the challenging issue of predicting the sound absorption and isolation performance of ceramic sound barriers and understanding the influencing factors on acoustic parameters, a simulation analysis method was employed for analyzing and studying various factors affecting the acoustic performance of these barriers. The calculation results demonstrate that increasing the thickness of both the sound absorption material and air layer behind exhibits similar effects on enhancing the sound absorption and isolation performance of ceramic acoustic barriers. Specifically, increasing either parameter leads to improved sound absorption performance by significantly increasing the sound absorption coefficient at 125Hz and 250Hz while decreasing it at 500Hz. However, in high-frequency bands above 1000Hz, structural parameters have minimal overall influence. Moreover, when keeping the thickness of ceramic sound absorption plates constant, every additional 20mm increase in air layer thickness behind results in a weighted increase in sound isolation by approximately 1dB; notable improvements are observed when this air layer thickness is below 1600Hz. When the thickness of the air layer behind is kept constant, an increase in the thickness of the sound absorption material by 10mm results in a 1dB increment in weighted sound isolation. However, when maintaining a total thickness of the sound barrier at 140mm, increasing the material’s thickness leads to a reduction in air layer thickness. Consequently, there is a slight enhancement in the sound absorption coefficient at frequencies of 125Hz and 250Hz while a minor decrease occurs at frequencies of 500Hz and 1000Hz. The impact on other frequency bands and overall sound absorption performance remains inconspicuous. Moreover, variations in weighted sound insulation quantity have minimal influence on sound insulation characteristics.

A novel comparison of southern sea otter (Enhydra lutris nereis) fur buoyancy across ontogeny.

Sea otters are extremely positively buoyant and spend most of their time resting at the water surface. It is understood that some of this buoyancy comes from the air layer that sea otters maintain in their pelage, with the lungs providing an additional source of positive buoyancy. Past studies have investigated the fur buoyant force in adult sea otters; however, little is known about the fur buoyant force in younger age classes. This study compared ontogenetic changes in the fur buoyant force of southern sea otter (Enhydra lutris nereis) pelage. We measured the fur buoyant force of pelt samples, scaled that to the whole animal, and calculated mass-specific fur buoyant force for six age classes: neonates (<1 month), small pups (1-2 months), large pups (3-5 months), juveniles (6months-1 year), subadults (1-3 years) and adults (4-9 years). Each pelt sample was measured under three conditions: control, oiled and washed with Dawn® dish soap. Oiled and washed pelts had a lower fur buoyant force compared with the control pelts across all age classes. When oiled, the air layer of the pelt is ruined and no longer provides sufficient positive buoyancy. Pelts washed with Dawn® had higher variability in buoyant force compared with other conditions, and the air layer was not restored consistently. When we scaled up, we found that younger age classes were more buoyant because of their larger surface area to volume ratio. These differences in buoyancy may underlie variations in energetic costs and behavior among sea otters across development.

РАННИЕ МЕТЕОРОЛОГИЧЕСКИЕ НАБЛЮДЕНИЯ В МОСКВЕ И АНАЛИЗ ИХ ДОСТОВЕРНОСТИ

The first regular meteorological observations in Moscow since 1779 have been investigated. New, previously unknown air temperature measurement data for 1783, 1784, 1816 and 1817 have been found and studied. The historical information about the installation conditions of thermometers and the effect on their readings of the walls of buildings in the era of window installation is summarized. It is noted that in the air layer from 0.5 to 7.0 m, the differences in the average annual temperature do not exceed ± 0.1 ° C. It is found that the total possible measurement error of the average daily temperature at the end of the XVIII century is no more than ± (0.3-0.4)°C. The close connections of the data from three neighboring stations (Moscow, St. Petersburg and Warsaw) confirm the high quality of measurements on the Mannheim network in the XVIII century. In 1816, the “year without summer", marked by abnormally cold weather on different continents due to the eruption of the Tambora volcano, the air temperature in Moscow in the summer months turned out to be low, but far from record lows.

Benzopyrene content in soil and atmosphere near boiler house

The paper considers a boiler house using firewood as fuel. The amount of combustion products and harmful substances such as nitrogen oxides, soot, carbon monoxide, suspended solids and benzopyrene formed during the combustion of 13 tons of birch wood per year is determined for it. Particular attention is paid to the content of benzopyrene as a substance capable of migrating from the atmosphere into water bodies, soil and belonging to the first hazard class, thereby affecting the quality of plant products, animal feed and human health. Being a strong carcinogen, benzopyrene affects the immune system, development processes, is capable of causing mutations and being transmitted to subsequent generations. Based on software, long-term average concentrations of benzopyrene in the air in the ground layer at a height of 2 m from the surface at eight points on the ground near the emission source and at the boundary of the corresponding sanitary protection for the boiler house under consideration were calculated. It was found that for this emission source, no excess of the content of this substance in the atmosphere is observed, and the influence of the wind rose on its dispersion is shown. Using laboratory studies of the soil near the source, it was found that the concentration of benzopyrene during its accumulation over 7 years on lands intended for agricultural use does not exceed the permissible values. Also, in the work, based on the law of conservation of energy and consideration of heat transfer from combustion products through a cylindrical wall into the surrounding space during transverse flow around the pipe, expressions are written that allow determining the temperature of the outgoing flue gases taking into account their thermophysical properties, pipe material and climatic features of the area.

Multi-Technique Characterization of Cartonnage and Linen Samples of an Egyptian Mummy from the Roman Period

The historical and cultural significance of artistic works and archaeological artifacts underscores the imperative use of non-destructive testing methods in cultural heritage objects. Analyzing pigments in artwork poses a specific analytical challenge that demands a combination of various techniques to accurately determine chemical compositions. In this context, our work focused on the multi-analytical characterization of samples derived from fragments of a Roman-era Egyptian mummy named Kherima, dating back to around 200 AD. To identify the layers and elemental composition of the pigments used in the decoration, various techniques were employed: X-ray microfluorescence (µXRF), X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), high-resolution optical microscopy (OM), and X-ray computed microtomography (microCT). This multi-analytical approach facilitated the identification of the original pigments in the analyzed mummy fragments, along with insights into the materials used in the ground layer and the techniques applied in artifact manufacturing, indicating their accordance with the historical period and region to which they originally belonged.

Bio-inspired catalysts for enhanced N₂ electroreduction to NH3: Architecting molecular screening interfaces via active sites microenvironment engineering

The electrochemical nitrogen reduction reaction (ENRR) promises a sustainable route for ammonia (NH3) production but faces hurdles from competing hydrogen evolution reaction (HER) and insufficient N2 concentration. Drawing inspiration from Tropical Lizards’ unique mechanism of creating a thin air layer on their hydrophobic skin, we modify the catalyst-water interface using alkyl thiols of different chain lengths on VS2 (Cx-VS2, x = 4,8,12). This novel approach suppresses HER and increases N2 availability. Among the tailored catalysts, C8-VS2 exhibits superior ENRR performance, with an ammonia yield of 58.43 μg h−1 mgcat−1 and a Faradaic efficiency of 34.69 % that surpasses unmodified VS2 (21.05 μg h−1 mgcat−1 and 8.87 %). Supporting measurements and density functional theory (DFT) calculations confirm the pivotal role of the modified interface in optimizing NH3 production. Our findings offer fresh perspectives for designing efficient electrocatalysts via tailoring interface microenvironments, with potential implications for various applications.

AC Zeeman effect in microfabricated surface traps.

Quantum processors and atomic clocks based on trapped ions often utilize an ion's hyperfine transition as the qubit state or frequency reference, respectively. These states are a good choice because they are insensitive in first order to magnetic field fluctuations, leading to long coherence times and stable frequency splittings. In trapped ions, however, these states are still subject to the second order AC Zeeman effect due to the necessary presence of an oscillating magnetic field used to confine the ions in a Paul trap configuration. Here, we measure the frequency shift of the 2S1/2 hyperfine transition of a 171Yb+ ion caused by the radio frequency (RF) electromagnetic field used to create confinement in several microfabricated surface trap designs. By comparing different trap designs, we show that two key design modifications significantly reduce the AC Zeeman effect experienced by the ion: (1) an RF ground layer routed directly below the entire RF electrode, and (2) a symmetric RF electrode. Both of these changes lead to better cancellation of the AC magnetic field and, thus, overall reduced frequency shifts due to the AC Zeeman effect and reduced variation across the device. These improvements enable a more homogeneous environment for quantum computing and can reduce errors for precision applications such as atomic clocks.

New potentially invasive species in the flora of Croatia - Diospyros virginiana L. (common persimmon)

During field research conducted from 2022 to 2023 on the island of Koločep, near the city of Dubrovnik, the spontaneous emergence of the non-native species Diospyros virginiana L. (common persimmon) was observed outside its primary cultivation area. This ornamental plant is part of the park dendroflora. D. virginiana began appearing spontaneously on the eastern side of the road between the two main settlements of the island, Gornje Čelo and Donje Čelo. It has established itself in an agricultural habitat within an abandoned olive grove covering an area of about 2900 m2. The plot, no longer under cultivation, is predominantly covered with ruderal and weedy vegetation, featuring an herbaceous ground layer identified as Dauco majori-Foeniculetum vulgaris. In this area, D. virginiana attains an average height of 1 to 2 meters, enveloping and suppressing the remaining Olea europaea L. trees. The plant spreads vegetatively and possesses a robust root system extending laterally for several meters, completely covering the area. Additionally, it has grown into a dry stone wall structure along the road. According to the author's proposal, it was recently entered in the FCD as 2.1.1.3, a potentially invasive species, to provide a basis for future monitoring. Considering its invasive potential and the environmental damage it may cause, the authors suggest the eradication of the species from the area before it spreads to surrounding regions.

Performance enhancements of HTS power cables by minimizing the electric field enhancements for electric transport applications

Abstract Design innovations to manage the electric field enhancements and successful use of cryogenic epoxy EP37 as electrical insulation for high temperature superconducting (HTS) cables for electric aircraft applications are reported. Detailed finite element analysis (FEA) of the electric field distribution shows that the highest electric field is at the interface of the ground and electrical insulation layers. The FEA led to the design, fabrication, and experimental characterization of four model cables with stress cones and a direct bond of the ground and insulation layers. Enhanced partial discharge inception voltage (PDIV) was achieved in the model cables by minimizing the electric field enhancements at the ground layer interface. Using a helium gas mixture with 4 mol% H2, with higher intrinsic dielectric strength than pure helium, further enhanced the PDIV. The results warrant further studies on long HTS cables with EP37 as electrical insulation with a direct bond between the insulation and ground layers.

Experimental and numerical investigation on the effect of ease allowance of clothing on thermal comfort

The heat transfer within the microclimate of clothing directly affects the thermal sensation of the human body, holding significant implications for both heat dissipation and cold protection. To investigate the variations in the heat transfer performance of the microclimate under the clothing influenced by distinct air gap thicknesses and diverse body postures, twelve female subjects participated in experiments wearing T-shirts with various ease allowances, conducting tasks in both sitting and standing positions within a climate chamber set at 20 °C and 50 % RH. Physiological parameters and subjective evaluations of comfort were recorded. Additionally, we constructed a three-dimensional model of the air gap featuring realistic morphology for numerical simulations of microclimatic heat transfer in a standing posture. The experimental results indicate that air gap thickness significantly impacts core temperature, mean skin temperature, local skin temperature, and thermal sensation. While postural differences did not show statistical significance, temperatures and thermal sensations were generally higher in the sitting position. Based on the results of numerical simulation, under this environmental condition, approximately 27 % of heat transfer was through radiation, with both the percentage of radiative heat transfer and the overall heat flux increasing with greater ease allowance. Furthermore, airflow under the clothing became more disorganized at thicker air layers, primarily concentrating in folds, hems, and sides of the body. This study provides a theoretical support for the workwear design and similar clothing and helps to reduce energy consumption in office environments.

Experimental study of dam-break-like tsunami loads on vertical structures with overhanging horizontal slabs: Slab with air chamber

Tsunamis pose a significant threat to coastal engineering. A comprehensive physical experiment was conducted to examine the effect of air chambers on vertical structures with overhanging horizontal slabs under tsunami bores. This paper, serving as the second part of the series, contrasts with conditions without air chambers (flat slab as Part I) to underscore the chamber's effects. The experiment employed dam-break waves to simulate tsunamis, and the collected pressure data and experimental images were analyzed. Results show that the chambers restrict water flow, thereby enhancing the impact on the slab. This focusing effect greatly increases both maximum uplift and horizontal pressure (by almost 1.3 times). The uplift pressure rises with increasing chamber volume, while horizontal pressure escalates with greater beam volume. However, both pressures diminish as slab height increases. Water flowing into the chambers disperses air, generating numerous bubbles that accumulate above, forming an air layer that reduces pressure signal fluctuations. This phenomenon of entrained and trapped air is compared and analyzed with existing literature. The maximum pressure of the nearshore air chamber is greater than that of the offshore air chamber by 13% (3.68 kPa vs. 3.27 kPa), while the quasi-steady pressures of the two are almost equal. Differences in pressure between chambers result from the sequence of water flow impacts and reflections. New design envelope equations and conversion coefficients are proposed based on experimental data. The focusing coefficient, considering bore height, slab height, and chamber parameters, is summarized. Novel equations for estimating pressure on a flat slab with specific chambers are proposed, with validation results indicating high accuracy.

A 27 ​GHz, simple 2-bit 1×8 phased array

This study demonstrates a simple 2-bit phased array operating at 27 ​GHz that supports one-dimensional beam scanning with left-handed circular polarization (LHCP). The antenna is constructed using a compact four-layer printed circuit board (PCB) structure, consisting of a 90° phase shifter layer with microstrip structures, a ground (GND) layer, a direct current (DC) control layer, and a circularly polarized annular radiation patch layer with 1-bit phase shifting. Based on the proposed unit structure, a 1×8 array with half-wavelength inter-element spacing was designed and validated. Experimental results show that the array achieves a peak gain of 10.23 dBi and is capable of beam scanning within ±50°.