Bed Thickness Research Articles

Terrestrial records of deglaciation events during terminations V and IV in the central Apennines (Italy) and insights on deglacial mechanisms

40Ar/39Ar geochronology constraints to aggradational phases and grain size variations show that the two large gravel beds occurring in the sedimentary filling of the Liri fluvial-lacustrine basin (central Italy) recorded the occurrence of deglaciation events synchronous within uncertainties with global meltwater pulses at ca. 450 and 350 ka. In particular, we find a precise match between the ages of gravel deposition and the occurrence of moderate sea-level rise events which anticipate those more marked during the glacial termination V and IV in the Red Sea relative sea level curve, as already verified by data from the Tiber River catchment basin. Such correspondence suggests that gravel deposition is facilitated by melting of Apennine mountain range glaciers, which provide the water transport energy and a surplus of clastic input to the rivers draining the mountain regions and flowing into the Tyrrhenian Sea. Therefore, the thick gravel beds intercalated in the sedimentary filling of the catchment basins of the major rivers in central Italy may be regarded as an equivalent proxy of large deglaciation events, similar to the ice-rafted debris in northern Atlantic. Consistent with this hypothesis, we also show the close correspondence between the occurrence of particularly mild (warmer) minima of the mean summer insolation at 65° N and these early aggradational phases, as well as with other anomalous early sea-level rises occurring c. 750 ka and 540 ka at the onset of glacial termination VIII and VI, and 40 ka at the onset of the so-called Heinrich events.

Feasibility study on the use of magnetic susceptibility for recovery of vanadium component in magnetite

ABSTRACT Vanadium in the vanadium-bearing titanomagnetite (VTM) exist by replacing iron in the magnetite crystal, and magnetite should be recovered separately from titanium components in the vanadium-bearing titanomagnetite. In the present study, a sensing system was proposed by measuring magnetic susceptibility of magnetite because the magnetic susceptibility can be easily and quickly measured. The effects of mixing ratio of magnetite and ilmenite with silica and the distance between the magnetic susceptibility meter and the sample bed on the magnetic susceptibility were investigated. The magnetic susceptibility of the mixture of magnetite and ilmenite with 0.1 g or 0.2 g of silica decreased with increasing the ratio of ilmenite in the mixture, but the effect of silica addition was not significant. When the distance between the magnetic susceptibility meter and the sample bed increased, the magnetic susceptibility of magnetite decreased, but the magnetic susceptibility decreased with increasing the thickness of magnetite sample bed of magnetite. Because the magnetic susceptibility depended strongly on the content of magnetite, the sensing system using the magnetic susceptibility measurement could be successfully applied to detect magnetite.

Regional Changes in Posterior Corneal Surface During a 6-Month Follow-up Period After tPRK, FS-LASIK, and SMILE.

To investigate changes in corneal curvature in different zones of the posterior corneal surface during a 6-month follow-up period after transepithelial photorefractive keratectomy (tPRK), femtosecond laser-assisted excimer laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE). The study included a total of 202 eyes, including 65, 77, and 60 that underwent tPRK, FS-LASIK, and SMILE, respectively. Elevation data for the posterior surface were obtained preoperatively (pre), as well as 1 week (pos1w), 1 month (pos1m), 3 months (pos3m), and 6 months (pos6m) postoperatively. Changes in posterior corneal curvature (M) were analyzed in the central (diameter: 0 to 3 mm), paracentral (diameter: 3 to 6 mm), and peripheral (diameter: 6 to 9 mm) regions. Over all follow-up periods, the central region of the posterior surface in all patients became flatter (P < .05), with FS-LASIK showing the largest change, whereas the paracentral and peripheral regions became steeper. The posterior curvature changes between pre and pos6m, determined before and after correction for ablated stromal depth, tended to follow similar trends in the three regions and after the three surgeries. There was also no significant correlation (P > .05) between the changes in the mean curvature (M, recorded between pre and pos6m) and each of the refractive error corrections, the changes in spherical aberration postoperatively, the optical zone diameter, ablated stromal depth, and residual stromal bed thickness in the central and peripheral regions, but the correlation was significant in the paracentral region. The postoperative changes in posterior corneal shape followed different trends in the central, paracentral, and peripheral regions. The FS-LASIK group exhibited the most notable changes in posterior corneal curvature, especially in the central region. These changes were statistically correlated with variations in spherical aberration, and ablated and residential stromal thickness in the paracentral region. [J Refract Surg. 2022;38(11):708-715.].

Rediscovering a valuable manual Deep Anterior Lamellar Keratoplasty (DALK) technique: Outcomes of 42 "Peeling-off" DALK.

Residual bed thickness in DALK should be less than 80μm to provide optimal visual outcomes. "Peeling-off" is a manual DALK technique, which separates the anterior stroma by pulling the deep stromal lamellae following the plane of their lowest adhesion, which is usually very deep. The purpose of this study is to measure the residual bed thickness achievable with this technique. Retrospective case series of "Peeling-off" DALK cases performed between January 2014 and January 2021 with at least 1 year of follow-up. Indications for DALK, intraoperative and postoperative complications, residual recipient bed thickness at 1 day and at 1 month after surgery, and postoperative best corrected visual acuity (BCVA) at 1 year of follow up were evaluated. 42 eyes (42 patients) underwent DALK performed with "Peeling-off" technique. Indications for surgery were keratoconus in 33 eyes and stromal scar in 9 eyes. "Peeling-off" technique was used as a rescue approach to perform a DALK after a failed Big-Bubble in all cases, and also failed Air-Visco-Bubble in some cases. No intraoperative and postoperative complications were recorded. Residual recipient bed thickness was deep and regular, measuring 42 microns at 1 day postoperative (range 21-65 microns) and 23 microns (range 17-26 microns) at 1 month postoperative. Mean postoperative BCVA at 1 year of follow up was 0.18 logMAR ± 0.09. "Peeling-off" DALK is a valuable manual technique that achieves a deep stromal plane with optimal visual outcomes.

Enhanced pool boiling heat transfer of multilayer copper-nanoparticle-packed beds by copper mesh coating

Pool boiling heat transfer has drawn a wide interest in dissipating high density heat flux produced by electronic products etc. In this work, the advantages of the copper mesh and the multilayer nanoparticle-packed beds in improving pool-boiling heat transfer was combined to give a good performance. The copper-nanoparticle-packed beds were firstly prepared, and then the effects of the layer thickness and porosity in the bed on the pool boiling heat transfer were explored. After obtaining the optimal thickness and porosity of the multilayer beds, the copper mesh was further coated on the multilayer beds to further enhance the pool-boiling heat transfer. Results turn out that: The increased thickness of the beds has a negative effect on enhancing heat transfer coefficient (HTC) because of the increased bubble-escape resistance, however, this effect will be set-off by the positive effect of the increased wetted area when the thickness was increase to be larger than 3 mm in this work. The onset of nucleate boiling of the optimal 4-layer beds without coating is about 1.7 °C which is much lower than most reported values, and the HTC is about 9 × 104 W/(m2·k) which is 9 times higher than that of the smooth surface. With the optimal bed further coated with copper mesh, the HTC can be further increased to 9.8 × 104 W/(m2·k). This enhancement arrives from the fact that the copper mesh prevents the continuous merging of bubbles, thus reducing the bubble detachment diameter by 30% and increasing detachment frequency of bubbles by 0.5 times.

Analysis of force–deformation and force–time profiles of 3D-printed specimens of single and binary mineral composition tested with Short Impact Load Cell

In mineral processing, accurate characterisation of the mechanical properties of particles of various mineral composite, texture and scale is critical for the development of improved breakage modelling. Additionally, these models should emphasise the primary breakage properties of the particles on the models rather than breakage in test devices that introduce substantial secondary fragmentation events. This work explores the use of the Short Impact Load Cell (SILC) test to investigate the mechanical properties of fabricated 3D-printed (3DP) specimens of single and binary mineral composition, i.e., iron oxide, silica, and layered specimens with both minerals. The fabricated quasi-identical specimens are useful to explore the repeatability and contrast of controlled additively manufactured 3DP specimens and the SILC testing performance. The fracture characteristics of printed quasi-identical specimens were observed using an ultra-high-speed digital camera. The study showed that the specimen properties, such as tensile strength and fracture energy are strongly influenced by the number of beds, bed thickness, and mineral composition. The force–deformation as well as force–time profiles and specimen fragmentation are studied to understand better the variability of the results and the specimen’s physical response to a single impact. The contour of force–time profiles allows for interpretations of how the striker contacts the specimen and to infer the crack initiation and fracture propagation through beds of brittle or ductile material. The use of hierarchical clusters facilitates the analysis as they enhance contrasts and give more insight into breakage and fragmentation, which is worthwhile investigating for natural rocks in the future.

Pyrolysis of forestry biomass and its effect over bed arrangements and thickness for the production of fuels

The present study highlights the performance of forestry biomass namely Babool wood, Chinaberry wood and Catalpa wood in a fixed bed reactor with varied biomass bed thickness and spacing between consecutive beds. Results revealed that several operating parameters including temperature, particle size, and heating rate greatly affected the pyrolysis process. Increasing the operating temperature from 500 °C to 600 °C increased the gaseous yield, while at low temperatures (350–450 °C), the liquid and char yields decreased due to removal of volatile fractions. Further, to improve the efficiency of the reactor, the biomass was placed in different bed arrangements. Results revealed that all the biomass were significant and gave highest yield of liquid products with four-bed arrangement. This study provides the insight of hardwood biomass having good thermal characteristics that makes them suitable for the production of fuels economically with low energy consumption.

Bed thickness-dependent fracturing and inter-bed coupling define the nonlinear fracture spacing-bed thickness relationship in layered rocks: Numerical modeling

Bed-normal fractures or joints are common in sedimentary basins (reservoirs). Fracture spacing S is an important parameter affecting both the mechanical stability and permeability of rock masses. Many studies have focused on predicting this parameter from the bed thickness T. Field measurements do show that S and T are related but frequently in a very nonlinear way so that at T > T0, S stabilizes at a certain value S0. Both T0 and S0 strongly vary in different settings. To understand this S(T) relationship, we conducted 2-D finite-difference modeling of a three-stratigraphic-layer system, where interfaces between competent and incompetent layers have different shear strength values τ. The models reproduce not only a general trend of the S(T) dependence in nature but also the observed variability of T0 and S0. These parameters are controlled in the models mostly by τ. T0 and S0 rapidly decrease with the τ increase, but the ratio T0/S0 ≈ 1.5 remains constant. At small T, the S(T) curves are linear, with slopes κ, whose reciprocal (1/κ) is linearly related to τ and increases with τ increase. The strong nonlinearity of S(T) relationship is explained by the T-dependence of the fracturing process obtained in the models.

Improving the drying performance of parchment coffee due to the newly redesigned drying chamber

AbstractThe Colombian coffee growers face many complications when using traditional open‐sun drying techniques such as post‐harvest process delays or incomplete grain dryness because of climate conditions. Therefore, local workshops began fabricating low‐capacity dryers simulating the industrial equipment working principles. One of the most commercialized units is a triple tray rectangular‐shaped dryer with a 31.25 kg capacity of dry parchment coffee per batch, providing the issue with an acceptable solution. However, it was redesigned into a circular shape holding a lower grain bed thickness and a vertical air inlet with a diffusive tray. Both units were simulated using the Thompson and the Michigan State University grain drying mathematical models to obtain their theoretical drying time. Then, a computational fluid dynamics simulation was conducted, attaining the unit's drying air behavior, the circular dryer exhibited notable drying times reduction and even air distribution, optimizing the dryer's performance, representing a benefit for the coffee‐growing farmers.Practical ApplicationsA cylindrical arranged coffee dryer with a vertical air inlet reduces the drying time of the grain, allowing a better rentability of the grower and improves the air distribution inside the equipment, meaning that the moisture removal will occur uniformly, safeguarding that the product's final moisture content meets the required conditions for safe storage.

A Finite Element Analysis of the Effects of Preheating Substrate Temperature and Power Input on Selective Laser Melting

Several parameters are defined before the Selective Laser Melting printing process, which may depend on the manufacturer of the equipment, but in general, we commonly encounter hatch distance, scanning speed, layer thickness, laser power input, scanning strategy, overlap distance, and substrate preheating temperature as the parameters that mainly define the printing process. The last parameter is the focus of this study, which is applied to a finite element model to simulate temperature distributions over one layer thickness of the powder bed. The substrate temperature and power input affect the cooling rates and temperature gradients imposed on the powder bed, consequently influencing the component’s final property, surface finishing, and accuracy (dimensioning tolerances). The current FEM model showed that the preheat substrate temperature played different roles depending on which power input is used; however, there is an observed trend that is the reduction in temperature gradients in the powder bed overall when higher substrate temperatures are used.

Research on the Influence of a Cuttings Bed on Drill String Friction Torque in Horizontal Well Sections

Horizontal well drills are difficult to operate and require high borehole cleaning operations. The impact of cuttings accumulation on friction and torque cannot be ignored. In the process of horizontal well drilling, it is very easy to form a cuttings bed in the highly inclined eccentric annulus. The formation of the cuttings bed will not only increase the friction torque but also have a greater impact on the annulus flow. Based on the application of gas drilling in horizontal wells, this paper uses laboratory experiments to study the influence of cuttings with different particle sizes and lithology on the friction coefficient between the drill string and the borehole wall of the horizontal well section. In addition, in view of the difficulty in the migration of cuttings in gas drilling horizontal wells and the formation of cuttings deposits, this paper carries out an experimental study on the effect of the cuttings bed on drill pipe coating height and cuttings bed thickness on friction coefficient. Experimental results show that the friction coefficient of gas drilling horizontal wells is about 0.44–0.58. When the coating height of the cuttings on the drill pipe exceeds a certain value (26 mm), the friction coefficient tends to be stable, but its value is as high as about 0.55. When the thickness of the accumulation of cuttings exceeds a certain value (10 mm), the subsidence hindering effect between the particles in the cuttings bed is weakened, so the friction coefficient of the casing section and the open hole section tends to be stable, about 0.53.

Long-Term Behaviour of Padded Concrete Sleepers on Reduced Ballast Bed Thickness

The positive effects of under sleeper pads have already been proven by track and laboratory tests worldwide. In Austria, padded concrete sleepers reduce track deterioration by 50 percent and have therefore been used as standard components since 2010. As the pads increase material costs, many infrastructure managers have discussed the idea of covering costs by reducing the ballast bed thickness. Technically, this approach (less ballast) is feasible, as the pads increase the track elasticity and protect the ballast. Further, pads lead to higher rail deflection and distribution of the load to more sleepers, and the stresses in sleepers are therefore relieved. Here, we compared Austrian test sections with padded and unpadded concrete sleepers and with a difference in the ballast bed thickness: standard thickness of 30 cm against 20 cm below the sleeper. Fractal analyses and standard deviations of the track’s longitudinal level provided information about the sections’ long-term track behaviour over 20 years. We found that the standard solution with 30 cm ballast performed better in the long term compared to 20 cm. Additionally, the test section with padded sleepers on a reduced ballast bed thickness showed a lower maintenance demand than the unpadded concrete sleeper track on a 30 cm ballast bed.

Palynology, Paleoenvironment and Stratigraphy Relationship of Tungan Buzu Hill with Adjacent Valley Gwandu Formation, Sokoto Basin, Northwestern Nigeria

Palynological study of Tungu Buzum Hill was investigated with a view towards determining the age of the outcrop, compare its miospore content with the adjacent Tungu Buzu Valley of carbonaceous shale, their stratigraphic relationship and paleoenvironment of deposition of the litho-sequence. Field study involved litho-description and logging achieved by noting the rock type, mineralogical composition, bed thickness, texture, sorting, roundness, structure, fossil content and diagenetic effect. Palynological slide preparation involved decarbonisation, digestion, sieving, maceral separation using zinc bromide, mounting on slide and petrographic analysis. The litho-sequence is composed sequentially upward of claystone, siltstone, indurated silty claystone, mudstone and ferruginized ironstone characterized by loadcast, fracture, lithification and bioturbation. Palynologically, the litho-section exhibits few marker forms such as Belskipollis elegans, Peregrinipollis nigericus and Retibrevitricolporites obodoensis depictive of early Miocene age. The paleoenvironment was deduced based on the occurrence of peridinacean forms such as Andalusiella sp., Senegalinium sp., Lejeuncysta diversiforma and Paleocystodinium golzowense indicative of marginal marine, while deeper marginal marine forms of gonyaulacacean phytoplanktons present are Micrhystridium sp., Canningia capillata and Dinogymnium sp. There are similarities in palynomorph assemblages of this study and Tunga Buzu Valley section in terms of age and similarity to Gwandu Formation though varied in paleoenvironment in the valley litho-section, marked by continental to marginal marine settings. Field relationship suggests that the Tunga Buzu Hill is stratigraphically overlying the Tunga Buzu Valley, separated by a fault. The Tunga Buzu Hill section represents the footwall while the Tunga Buzu Valley is situated within the hanging wall of a normal fault structure.

Powder-bed-fusion additive manufacturing of molybdenum: Process simulation, optimization, and property prediction

In this paper, the whole process of laser powder-bed-fusion (LPBF) additive manufacturing (AM) in the fabrication of molybdenum (Mo) material was numerically reproduced. Firstly, parameters of Mo powder with continuous size distribution utilized in actual AM production were calibrated and input into discrete element model (DEM) for parametric study on powder spreading. Then, the laser melting of the spread powder bed was simulated by computational fluid dynamics (CFD). On this basis, a back propagation neural network (BPNN) model was built for powder bed quality and molten track property prediction and evaluation. Results show that properly reducing the spreading velocity V or increasing the gap height H can contribute to the optimal structure of the powder bed. Corresponding mechanism analyses reveal that the residual velocity of particles and force chain block are the main reasons for the decrease of powder bed quality. And the molten track performance is not positively correlated with the packing density of the powder bed due to the defects such as balling and porosity caused by the over-thickness of powder bed. The selection rule of powder bed should satisfy as higher as possible the packing density within the bed thickness threshold. The BPNN model can accurately predict the powder bed quality and the molten track property and develop a reasonable map for the appropriate choice of operating parameters in real processes.

Исследование частоты встречаемости клинически тонкой роговицы у пациентов с миопией средней и высокой степени, обратившихся для выполнения кераторефракционной операции

Purpose. To assess frequency of occurrence patients with insufficient thickness of optical zone of cornea for complete elimination of myopic refraction using FemtoLASIK technology. Material and methods. By random sampling, 100 patients (200 eyes) were selected with varying degrees of myopia who planned refractive surgery using the FemtoLASIK or Smile technology. The selection criterion was presence the prognosis of residual myopia in eyes due to the inability to fulfill the required ablation depth of the optical zone. The share of such patients in the total population of selected patients, their gender, age, magnitude of residual myopic refraction were found out. Results. According to results of the study in 88 patients (176 eyes, 88 %) thickness of optical zone of cornea made it possible to completely eliminate the existing myopic refraction) using the FemtoLASIK or Smile technology. In 12 patients (24 eyes, 12 %) thickness of optical zone of cornea did not made it possible to completely eliminate myopic refraction, without critical thinning of the stromal bed of cornea. The predicted residual myopia in these eyes ranged from –1.0 to –2.5 diopters. Photorefractive keratectomy technology was offered to these patients, which was agreed by 8 patients (16 eyes). Conclusion. The obtained data revealed the high relevance of the development of femtolaser refractive surgery technology, which provides for the complete elimination of myopic refraction in such patients by reducing the thickness of the corneal surface valve and, accordingly, increasing the thickness of the stromal bed. Keywords: refractive surgery, residual myopia, ablation depth, FemtoLASIK, corneal surface valve, residual stromal bed thickness.

NON-MARINE BIVALVES FROM THE MOSPYNE FORMATION (UPPER BASHKIRIAN) OF THE DONETS BASIN: TAXONOMY, PALEOECOLOGY, AND STRATIGRAPHIC SIGNIFICANCE

Remains of non-marine bivalves are widespread in the Carboniferous of the Donets Basin (Eastern Ukraine). The studies of this group of fauna are important for stratigraphy, paleoecology and paleobiogeography. The remains of non-marine bivalves were found in sediments of the Mospyne Formation; Carbonicola obtusa (Hind) and Naiadites sp. were found in the roof shale of the g2 coal bed; Curvirimula trapeziforma (Dewar) and C. tesselata (Jones) were identified in the roof shale of the g12 coal bed, and Carbonicola rectilinearis Trueman et Weir and C. limax Wright were found in the siltstone below G12 limestone layer. The upper part of the lower half of the Mospyne Formation is attributed to the Carbonicola rectilinearis Member, which probably corresponds to the upper part of the lenisulcata Zone (Langsettian) of Western Europe. The lower limit of this member is in the floor of a thick sandstone bed 43 m below G12 limestone layer. The upper boundary of Carbonicola rectilinearis Member is situated at the g12 coal layer. The Carbonicola pseudorobusta Zone, previously identified by M.T. Sergeeva as member with fauna, is distinguished between the roof shale of the g12 coal bed and h61 coal bed. This zone corresponds to the communis Zone in Western Europe. Bivalves from the roof shale of the g12 coal layer and roof shale of the g2 coal layer lived in shallow-water eutrophic freshwater or brackish lakes in the coastal accumulation lowland. These basins were characterized by significantly reduced aquatic organism assemblage and hydrogen sulfide contamination of silts and, possibly, the bottom layer of the water column. Representatives of the genera Curvirimula and Naiadites were found in the sediments of these lakes. These genera apparently led a pseudoplanktonic lifestyle, attaching themselves to various bottom objects with byssus. The bivalves from the siltstones below the G12 limestone layer (Carbonicola) lived in a shallow-water, refreshed lagoon.

Corneal aberrations, densitometry on scheimpflug imaging, and visual acuity after deep anterior lamellar keratoplasty.

To evaluate visual acuity, corneal aberrations, and densitometry post deep anterior lamellar keratoplasty (DALK). Twenty-five eyes of 25 patients who underwent DALK for corneal stromal diseases with normal endothelium were enrolled in a prospective interventional study. Evaluation for corneal aberrations and densitometry postoperatively was performed using Scheimpflug imaging at 6 months. Anterior Segment Optical Coherence Tomography (ASOCT) was done for host-graft morphology. Correlation analysis of postoperative best-corrected visual acuity with corneal aberrations and corneal densitometry (CD) was performed. Big bubble deep anterior lamellar keratoplasty (BB-DALK) was successful in 18 patients, while 7 eyes underwent manual dissection due to failed BB (Big Bubble) technique. The mean BSCVA was 1.35 ± 0.46 logMAR units pre-operatively which improved to 0.36 ± 0.19 logMAR units post DALK at 6 months (P < 0.001). The mean Root Mean Square (RMS) (μm) of the magnitude of total corneal aberrations, HOA and LOA from central 6mm zone of cornea were 14.6 ± 9.2, 4.7 ± 2.9, and 13.8 ± 8.8, respectively. The mean anterior (120μm), central and posterior corneal (60μm) densitometry in 0-2mm zone were 25.8 ± 7.7 GSU, 18.7 ± 4.16 GSU and 10.09 ± 3.9 GSU respectively. A statistically significant correlation of postoperative residual stromal bed thickness, total corneal HOA, LOA, total corneal aberrations, HOA front and posterior corneal densitometry (0-2mm zone) with postoperative BSCVA was found. Though there is a significant improvement in BSCVA after DALK, the quality of vision in terms of aberrometry and densitometry is suboptimal, especially in cases undergoing manual DALK compared to those undergoing big bubble formation.

Controls of dolomitization and bed thickness on fracture networks in Lower Carboniferous carbonates in southern Belgium

Fracture networks in limestone and dolostone quarries in southern Belgium were analyzed as analogues to fractured subsurface Lower Carboniferous carbonates in the Campine-Brabant Basin (northern Belgium, southern Netherlands and westernmost Germany), which are considered as potential geothermal reservoirs. This study focuses on the difference in fracture density, intensity and connectivity in dolostone and limestone quarry walls, as well as on the relationship between bed thickness and fracture density/intensity. Bedding planes and fractures were interpreted based on orthorectified images of quarry walls. Statistical tests show that fracture density and intensity are significantly larger in the dolostones than in the limestones, which is explained by rock mechanical properties. Fracture connectivity is also highest in the studied dolostones. Interpreted bed thickness is significantly larger in limestones than dolostones, but no correlation is present between bed thickness and fracture density or intensity. This may be explained by the low percentage of bed-bounded fractures in the quarry walls. Fracture density, intensity and connectivity are key parameters influencing permeability, especially in carbonates with low matrix porosity. The results suggest that, in light of fracture properties, Lower Carboniferous dolostones might possess better geothermal reservoir characteristics than limestones.

The role of climatic factors in seasonal differences of CO2 emission from the soil and litter of broadleaf forest phytocoenoses

The article presents the results of the study of the intensity of carbon dioxide emission from the forest bedding and soil in the broad-leaved phytocoenosis of the National Nature Park “Holosiivskyi” (Kyiv green belt) in the spring and autumn periods of the year. The research was conducted in the autumn period in October, and in the spring period in April. Site coordinates: 50°17′52.7″N, 30°32′34.4″E. The experimental plot (50 × 50 m) was represented by the association Convallario majali-Quercetum roboris Shevchyk &amp; V. Sl. in Shevchyk &amp; al. 96, union Convallario majali-Quercion roboris Shevchyk, V. Sl. 96. It has been established that more intensive emission of CO2 occurs in the spring period compared to the autumn period. In the spring period of the year, the intensity of carbon dioxide emission from the forest litter and soil in the broad-leaved phytocoenosis ranged from 56.12 to 99.27 μmol CO2·m-2·min-1 and averaged 74.51 μmol of CO2·m-2·min-1. These differences depended on the amount of organic matter in the soil, the density of soil composition, the presence and size of tree roots, as well as the thickness of the forest bedding at the measurement points. In the autumn period of the year, the intensity of carbon dioxide emission from the forest bedding and soil was lower and in average was 68.52 μmol CO2·m-2·min-1. It was found out that higher values of carbon dioxide emissions in the spring period were determined by differences in temperature and humidity. Important factors were the increase in the supply of organic substances in the soil and more intensive processes of decomposition of these substances in the spring. Correlational analysis of the influence of climatic factors on the intensity of carbon dioxide emission proved the predominant role of temperature (r = 0.45) and a smaller influence of humidity (r = 0.15) of air and soil. In general, the conducted research confirmed the importance of monitoring the CO2 emission index of the forest bedding and soil respiration as indicators of the stability of forest ecosystems in the face of climate change.

Characteristics of Pyrolysis and Copyrolysis Products Sewage Sludge in Different Temperature Ranges

Rapid modernization, population growth, and improvement in people’s quality of life have resulted in an increase in urban sewage sludge as the main solid waste. At present, pyrolysis is the main treatment method for sludge due to carbon-free effects and less air pollution compared with incineration. To enhance the energy utilization value of sludge, copyrolysis of sludge and biomass with varying effects has been reported. Herein, biomass and sludge were pyrolyzed and copyrolyzed using self-designed fixed-bed pyrolysis and condensation collection system. The pre-fixed-bed process parameters were optimized by orthogonal test, and it was found that the carrier gas flow rate (a) &gt; bed thickness (b) &gt; constant temperature time (c). The optimum process combinations were 250 mL/min carrier gas, 10 mm bed thickness, and 10 min constant temperature. Experiments show that the ultimate pyrolysis temperature affects the oil production of fixed-bed pyrolysis by up to 15%. Copyrolyzing Sargassum thunbergii and sludge boost oil output at first and then drops; the maximum value is at 20% sludge. When pine sawdust and sludge were copyrolyzed, oil output climbed marginally and subsequently fell fast; the highest value was at 20% sludge. Peanut shell and sludge copyrolysis yield the most oil at 40% sludge content, and the experimental value is smaller than the linear value at 80% sludge content.