Bed Conditions Research Articles

Integrity Assessment of Wall Distorted of Buried Gas Pipeline

In the oil and gas industry, the pipeline is the main mode to transport the product and can be applied for long-distance transportation; hence some pipe segments may be buried underground. Buckling as the main cause of pipeline deformation and failure is often found at the in-service buried pipeline during inspection activity. Changes in laying conditions such as design and operational parameters, human activity and geological movement can affect the redistribution of deformation that may lead to pipe buckling. This paper presents a methodology that integrates inspection results and finite element analysis for the distorted wall of the pipeline. Inspection reported anomaly cases of wall distorted at buried gas pipeline, and the result will be used to do stress analysis using finite element analysis. Three different conditions within the different treatment of bedding conditions were assessed: pipe buried on uncompacted soil, pipe buried with rock bedding, and pipe buried in compacted soil. The result shows that the deteriorated pipe can be considered acceptable when buried in compacted soil. This condition may be used for further action and consideration, such as a mitigation strategy to maintain the safety and integrity of the deteriorated pipe.

Sex differences in addiction-relevant behavioral outcomes in rodents following early life stress

In humans, exposure to early life stress (ELS) is an established risk factor for the development of substance use disorders (SUDs) during later life. Similarly, rodents exposed to ELS involving disrupted mother-infant interactions, such as maternal separation (MS) or adverse caregiving due to scarcity-adversity induced by limited bedding and nesting (LBN) conditions, also exhibit long-term alterations in alcohol and drug consumption. In both humans and rodents, there is a range of addiction-related behaviors that are associated with drug use and even predictive of subsequent SUDs. In rodents, these include increased anxiety-like behavior, impulsivity, and novelty-seeking, altered alcohol and drug intake patterns, as well as disrupted reward-related processes involving consummatory and social behaviors. Importantly, the expression of these behaviors often varies throughout the lifespan. Moreover, preclinical studies suggest that sex differences play a role in how exposure to ELS impacts reward and addiction-related phenotypes as well as underlying brain reward circuitry. Here, addiction-relevant behavioral outcomes and mesolimbic dopamine (DA) dysfunction resulting from ELS in the form of MS and LBN are discussed with a focus on age- and sex-dependent effects. Overall, these findings suggest that ELS may increase susceptibility for later life drug use and SUDs by interfering with the normal maturation of reward-related brain and behavioral function.

Impacts of autochthonous particulate organic matter on redox-conditions and elimination of trace organic chemicals in managed aquifer recharge

Autochthonous carbon fixation by algae and subsequent deposition of particulate organic matter can have significant effects on redox conditions and elimination of trace organic chemicals (TOrCs) in managed aquifer recharge (MAR). This study investigated the impacts of different algae loadings (0–160 g/m2) and infiltration rates (0.06–0.37 m/d) on overall oxygen consumption and elimination of selected TOrCs (diclofenac, formylaminoantipyrine, gabapentin, and sulfamethoxazole) in adapted laboratory sand columns. An infiltration rate of 0.37 m/d in conjunction with an algae load of 80 g/m2 (dry weight) sustained oxic conditions in the sand bed and did not affect the degradation of TOrCs. Thus, the availability of easily degradable organic carbon from algae did not influence the removal of TOrCs at an influent concentration of 1 µg/L. In contrast, a lower infiltration rate of 0.20 m/d in combination with a higher algae loading of 160 g/m2 caused anoxic conditions for 30 days and significantly impeded the degradation of formylaminoantipyrine, gabapentin, sulfamethoxazole, and diclofenac. Especially the elimination of gabapentin did not fully recover within 130 days after pulsed algae deposition. Hence, measures like micro-sieving or nutrient control are required at bank filtration or soil aquifer treatment sites with low infiltration rates.

Factors controlling bed and bank erosion in the Illgraben (CH)

Debris flows can grow greatly in size and hazardous potential by eroding bed and bank materials. However, erosion mechanisms are poorly understood because debris flows are complex hybrids between a fluid flow and a moving mass of colliding particles, bed erodibility varies between events, and field measurements are hard to obtain. Here, we (i) quantify the spatio-temporal patterns of erosion and deposition and (ii) identify the key controls on debris-flow erosion in the Illgraben (CH). We use a dataset that combines information on flow properties, antecedent rainfall, and bed and bank erosion for 13 debris flows that occurred between 2019 and 2021. We show that spatio-temporal patterns of erosion and deposition in natural debris-flow torrents can be highly variable and dynamic, and we identify a memory effect where erosion is strong at locations of strong deposition during previous flows and vice versa. We find that flow conditions and antecedent rainfall (affecting bed wetness) jointly control debris-flow erosion. We find statistically significant correlations between channel erosion/deposition and a wide range of flow conditions, including frontal flow depth, velocity, and discharge, and flow volume, cumulative shear stress and seismic energy, as well as antecedent rainfall. Overall, flow conditions describing the cumulative forces exerted at the bed during an event, such as cumulative shear stress and flow volume, best explain erosion. A shear-stress approach accounting for bed erodibility may therefore be applicable for modelling and predicting debris-flow erosion. This work can provide input for model development by identifying correlations of flow and bed conditions with erosion that models should oblige.

A new statistical method to assess potential debris flow erosion

Debris-flow erosion patterns were investigated for two adjacent catchments, Molinara and Val del Lago creeks (Eastern Alps, Trento Province, Italy), where two debris flows were triggered by an intense storm in the summer of 2010. Both basins have been inactive over the last two centuries. The debris flows were activated by channel and bank erosion under stable bed conditions before the event. The erosive process was analysed by combining a field campaign (two hundred cross sections were surveyed along the creeks) and pre- and post-event LiDAR surveys. Data were analysed by selecting morphologically-homogenous channel reaches and deriving for each reach: erosion depth, creek width, eroded volume and peak discharge. Investigating the frequency distribution of the erosion depth we found out that it follows an EV1 probability distribution. On this basis, a new approach has been proposed to predict event volumes when the expected maximum potential depth erosion is known. The procedure would be of high interest in predicting debris flow volume in mountain channels characterized by long silent periods.

Geochemistry of the Transitional beds between Disang and Barail Successions of the Imphal Valley, Indo-Myanmar Ranges

Major and trace element concentrations were studied from the tansitional beds between Disang and Barail Successions of the Imphal valley, Indo-Myanmar Ranges. Various major and trace element ratios and discrinant diagrams were used to descipher paleoclimate, paleo-redox condition and sedimentary depositional environment of the Disang-Barail Transitional beds. SiO2 vs Al2O3+K2O+ Na2O diagram and Rb/Sr ratios indicates that paleoclimate during the deposition of the sediments changed from arid to semi-arid and humid climate. Ni/Co, V/Cr, V/(Ni+V), V/Sc ratios suggest that these sediments were deposited in oxic, suboxic to anoxic conditions. V/(Ni+V) vs V/Cr diagram suggests paleo-redox environment dominated by sub-reduction to oxidization during Disang –Barail Transitional deposition. The sediments were deposited in transitional to marine depositional environment.

Ash characterisation formed under different oxy-fuel circulating fluidized bed conditions

The CO2-intensive oil shale power industry accounts for more than 70% of the Estonian energy sector, producing large amounts of ash that are mainly landfilled. Adopting oxy-fuel technology in the Estonian energy sector, in conjunction with CO2 storage, can be a critical tool for reducing carbon footprint. Nevertheless, several differences in ash formation under oxy-fuel conditions can be expected, which can lead to additional ash handling/utilization and related environmental concerns. In this context, the composition of oil shale ash was obtained from a series of combustion experiments in a 60 kWth circulating fluidized bed (CFB) test unit under both air and oxy-fuel combustion regimes studied by means of physical, chemical analysis as quantitative X-ray diffraction and element analysis for ashes from different separation ports. During the experimental work, special attention was given to understanding the impacts of the boiler temperature, recycled flue gas (RFG), and elevated oxygen concentration. As a result, the primary goal of this research is to characterise the ash produced by oxy-fuel combustion of oil shale in order to gain a better understanding of its chemical and mineral compositions, including Ca-Mg silicates and clay minerals, as well as to investigate the behaviour of the formation of free lime and anhydrite, which are the major compounds influencing potential ash utilisation routes. The results show that although the decomposition of calcium carbonates was limited during oxy-fuel combustion because of the high CO2 partial pressure, the contents of secondary silicates and anhydrite were slightly higher. The increased particle temperature and the higher SO2 partial pressure (with RFG) can explain this. The particle size distributions (PSDs) were wider under oxy combustion, and the specific surface area (SSA) in Filter ashes were much higher under elevated inlet O2% atmosphere. Oxy-fuel combustion had no significant impact on the concentration of elements in the ash. Overall, the mineralogy of the ashes formed in air and oxy-fuel combustion environments is similar, yet slight differences exist in the formation of clay minerals in the case of increased oxygen concentrations and with the application of RFG as a result of the increased residence time of the particles.

Influence of early-life adversity on responses to acute and chronic ethanol in female mice.

Stressful early-life experiences increase the risk of developing an alcohol use disorder. We previously found that male C57BL/6J mice reared under limited bedding and nesting (LBN) conditions, a model of early-life adversity, escalate their ethanol intake in limited-access two-bottle choice (2BC) sessions faster than control (CTL)-reared counterparts when exposed to chronic intermittent ethanol (CIE) vapor inhalation. However, the alcohol consumption of female littermates was not affected by LBN or CIE. In the present study, we sought to determine whether this phenotype reflected a general insensitivity of female mice to the influence of early-life stress on alcohol responses. In a first experiment, CTL and LBN females with a history of 2BC combined or not with CIE were tested in affective and nociceptive assays during withdrawal. In a second group of CTL and LBN females, we examined ethanol-induced antinociception, sedation, plasma clearance, and c-Fos induction. In females withdrawn from chronic 2BC, CIE increased digging, reduced grooming, and increased immobility in the tail suspension test regardless of early-life history. In contrast, LBN rearing lowered mechanical nociceptive thresholds regardless of CIE exposure. In females acutely treated with ethanol, LBN rearing facilitated antinociception and delayed the onset of sedation without influencing ethanol clearance rate or c-Fos induction in the paraventricular nucleus of the hypothalamus, paraventricular nucleus of the thalamus, central nucleus of the amygdala, or auditory cortex. CIE withdrawal produced multiple indices of negative affect in C57BL/6J females, suggesting that their motivation to consume alcohol may differ from air-exposed counterparts despite equivalent intake. Contrasted with our previous findings in males, LBN-induced mechanical hyperalgesia in chronic alcohol drinkers was specific to females. Lower nociceptive thresholds combined with increased sensitivity to the acute antinociceptive effect of ethanol may contribute to reinforcing ethanol consumption in LBN females but are not sufficient to increase their intake.

Rediscovering wood‐laden debris flow studies: A perspective from Japan

AbstractDebris flow is one of the dominant processes distributing large wood (LW) within mountainous catchments. However, little has been reviewed on wood‐laden debris flow (WLDF), presumably owing to limited reviewable works. This article, therefore, navigates the international readers through 40 years of WLDF studies, most of which have been published only in Japanese. Firstly, we reviewed the historical development of Japanese WLDF particularly focusing on the 1980s and the 1990s. A series of post‐disaster fieldworks from the July 1982 Nagasaki flood to the July 1990 Kumamoto flood provided 32 catchment‐scale wood budgeting data; empirical relationships among drainage area, dominant tree species, sediment yield, and wood loads associated with single debris flow disasters were illustrated. Secondly, the characteristics of WLDF were summarized based on relevant previous studies on the recruitment, transport, and deposition processes of LW during debris flows. Thirdly, we discussed the connectivity between those Japanese WLDF studies and international LW studies by relating/contrasting their research approaches and spatiotemporal scales. In contrast to global LW research trends, Japanese WLDF studies have almost exclusively regarded LW as hazardous materials (i.e., “driftwood” or “woody debris”) that need to be retained upstream of the inhabited areas. Those practice‐oriented WLDF studies were concentrated on drainage areas of 10−2 to 100 km2, representing 1–6 orders of magnitude smaller spatial scales than those generally covered by existing international LW studies. Strongly motivated by engineering requirements, “dynamic” interactions between debris flows and LW during floods have also been physically presented, mainly based on unique laboratory experiments involving steep flume (> 0.05) and mobile bed conditions. Finally, some future works for WLDF were briefly stated from practical and scientific perspectives. By “rediscovering” those WLDF studies domestically developed in Japanese debris flow channels since the 1980s, a more comprehensive understanding of LW dynamics in the river system may be achieved.

The effect of mild to moderate sleep restriction on subjective hunger in healthy young men

There is good evidence to indicate severe sleep restriction increases subjective feelings of hunger, but the impact of mild to moderate sleep restriction (i.e., 5–7 h) on hunger has not been systematically evaluated. Healthy male participants (n = 116; 22.8 ± 2.1 years; 22.9 ± 3.7 kg⋅m−2) were recruited to a ten-day laboratory study. In a between groups design, participants were allocated to one of five time in bed conditions (5 h, 6 h, 7 h, 8 h or 9 h) for seven consecutive nights. Participants were provided a eucaloric diet and ratings of hunger, nausea and desire to eat certain foods were collected using visual analogue scales prior to meals (breakfast, lunch, afternoon snack, dinner and evening snack) on four days during the study. Data were analysed using linear mixed models with time in bed, time of day and study day as fixed effects and participant as a random effect. There was no main effect of time in bed, and no interaction between time in bed and study day, on hunger, nausea, prospective hunger or desire to eat certain foods. However, post-hoc analyses indicated that participants in the 5-h condition had an elevated desire to consume sweet foods and fruit on the final morning of the protocol. There was a main effect of time of day and study day on hunger; participants were hungriest prior to lunch time and hunger decreased over consecutive days of the protocol. When provided with a eucaloric diet, only 5-h time in bed increased desire to consume sweet foods and fruit in healthy young men.

Mapping of quench front propagation in a heated cylindrical particle bed – MONET tests

In case of a severe accident in nuclear reactor, a debris bed may be formed from the fragmentation of the molten core at different stages of the accident. Debris bed coolability is an important issue, as it will determine the accident progression, its termination, and mitigation. One of the major concerns of debris bed coolability investigations is to understand and evaluate the effect of water re-flooding. Many experiments have been conducted to study the two-phase flow and heat transfer in porous medium configuration. However, the understanding of debris bed quenching with multi-dimensional characteristics are limited. Here, a test facility MCCI-mitigatiON through passive cooling Effect Test (MONET) apparatus is established to conduct the porous debris bed re-flooding investigation. The objective is to understand the mechanism of heat transfer and quench front movement inside the cylindrical heated debris bed during quenching by cooling water supplied from the bottom of the bed. Specifically, the effect of Homogeneous bed (with different external boundary conditions) and radially stratified bed (with different internal porosity configurations) conditions of the cylindrical debris bed on the quench front movement has been investigated. The particulate debris bed is formed with two different types of particles (SS 304, alumina) and sizes (2–3.5 mm). The effect on the quench front movement inside the particle bed has been reported by using temperature measurements together with direct visualizations. Present findings suggest non-uniform quench front propagation pattern even for the homogeneous bed conditions. While the tests with the stratified bed indicate a clear influence of low porosity region on the quench front and vapor movement.

Mild to Moderate Sleep Restriction Does Not Affect the Cortisol Awakening Response in Healthy Adult Males.

The cortisol awakening response (CAR) is a distinct rise in cortisol that occurs upon awakening that is thought to contribute to arousal, energy boosting, and anticipation. There is some evidence to suggest that inadequate sleep may alter the CAR, but the relationship between sleep duration and CAR has not been systematically examined. Healthy males (n = 111; age: 23.0 ± 3.6 yrs) spent 10 consecutive days/nights in a sleep laboratory. After a baseline night (9 h time in bed), participants spent either 5 h (n = 19), 6 h (n = 23), 7 h (n = 16), 8 h (n = 27), or 9 h (n = 26) in bed for seven nights, followed by a 9 h recovery sleep. The saliva samples for cortisol assay were collected at 08:00 h, 08:30 h and 08:45 h at baseline, on experimental days 2 and 5 and on the recovery day. The primary dependent variables were the cortisol concentration at awakening (08:00 h) and the cortisol area under the curve (AUC). There was no effect of time in bed on either the cortisol concentration at awakening or cortisol AUC. In all the time in bed conditions, the cortisol AUC tended to be higher at baseline and lower on experimental day 5. Five consecutive nights of mild to moderate sleep restriction does not appear to affect the CAR in healthy male adults.

Slag Flow in the Packed Bed With Varied Properties and Bed Conditions: Numerical Investigation

Molten slag, which is primarily generated in the blast furnace (BF) cohesive zone, trickles down through the coke packed bed in the form of films, rivulets, or droplets in the lower zone of the BF. During its downward flow, there are significant interactions occurring between slag and other phases such as gas, coke particles, hot metal, and fine powders. In terms of these interactions, slag flow behavior can greatly affect BF productivity and be associated with furnace irregularities such as channeling, hanging, and slipping. Hence, understanding the interactions between phases is useful to maximizing BF efficiency in terms of operating cost, reliability, and production capacity. In the current study, a Volume of Fluid (VOF) modeling technique was applied to track the movement of individual slag droplets in the packed bed at a mesoscopic level, considering various bed permeabilities, more wide-ranging slag properties, and different wettability between slag and packing particles. Results demonstrate the significant role of modeling at a mesoscopic level in understanding macroscopic slag flow behavior. Modeling work helps to visualize the trickling behavior of slag droplets in more realistic and complex conditions representing a BF, and clarify the mechanisms of the different flow patterns generated for variations in operating conditions. Transient flow characteristics such as localized slag accumulation and droplet morphology were identified and analyzed in relation to complex condition changes. The current modeling proved to be a valuable tool to provide a foundation for better understanding the slag flow behavior and its interactions with other phases in the BF lower zone.

Improving soil organic carbon predictions from a Sentinel–2 soil composite by assessing surface conditions and uncertainties

Soil organic carbon (SOC) prediction from remote sensing is often hindered by disturbing factors at the soil surface, such as photosynthetic active and non–photosynthetic active vegetation, variation in soil moisture or surface roughness. With the increasing amount of freely available satellite data, recent studies have focused on stabilizing the soil reflectance by building reflectance composites using time series of images. Although composite imagery has demonstrated its potential in SOC prediction, it is still not well established if the resulting composite spectra mirror the reflectance fingerprint of the optimal conditions to predict topsoil properties (i.e. a smooth, dry and bare soil).We have collected 303 photos of soil surfaces in the Belgian loam belt where five main classes of surface conditions were distinguished: smooth seeded soils, soil crusts, partial cover by a growing crop, moist soils and crop residue cover. Reflectance spectra were then extracted from the Sentinel–2 images coinciding with the date of the photos. After the growing crop was removed by an NDVI < 0.25, the Normalized Burn Ratio (NBR2) was calculated to characterize the soil surface, and a threshold of NBR2 < 0.05 was found to be able to separate dry bare soils from soils in unfavorable conditions i.e. wet soils and soils covered by crop residues. Additionally, we found that normalizing the spectra (i.e. dividing the reflectance of each band by the mean reflectance of all spectral bands) allows for cancelling the albedo shift between soil crusts and smooth soils in seed–bed conditions. We then built the exposed soil composite from Sentinel–2 imagery for southern Belgium and part of Noord-Holland and Flevoland in the Netherlands (covering the spring periods of 2016–2021). We used the mean spectra per pixel to predict SOC content by means of a Partial Least Squares Regression Model (PLSR) with 10–fold cross–validation. The uncertainty of the models was assessed via the prediction interval ratio (PIR). The cross validation of the model gave satisfactory results (mean of 100 bootstraps: model efficiency coefficient (MEC) = 0.48 ± 0.07, RMSE = 3.5 ± 0.3 g C kg–1, RPD = 1.4 ±0.1 and RPIQ = 1.9 ± 0.3). The resulting SOC prediction maps show that the uncertainty of prediction decreases when the number of scenes per pixel increases, and reaches a minimum when at least six scenes per pixel are used (mean PIR of all pixels is 12.4 g C kg–1, while mean SOC predicted is 14.1 g C kg–1). The results of a validation against an independent data set showed a median difference of 0.5 g C kg–1 ± 2.8 g C kg–1 SOC between the measured (average SOC content 13.5 g C kg–1) and predicted SOC contents at field scale. Overall, this compositing method shows both realistic within field and regional SOC patterns.

Intravenous Nicotinamide Riboside Administration Has a Cardioprotective Effect in Chronic Doxorubicin-Induced Cardiomyopathy.

Doxorubicin, which is widely used to treat a broad spectrum of malignancies, has pronounced dose-dependent side effects leading to chronic heart failure development. Nicotinamide riboside (NR) is one of the promising candidates for leveling the cardiotoxic effect. In the present work, we performed a comparative study of the cardioprotective and therapeutic actions of various intravenous NR administration modes in chronic doxorubicin-induced cardiomyopathy in Wistar rats. The study used 60 mature male SPF Wistar rats. The animals were randomized into four groups (a control group and three experimental groups) which determined the doxorubicin (intraperitoneally) and NR (intravenous) doses as well as the specific modes of NR administration (combined, preventive). We demonstrated the protective effect of NR on the cardiovascular system both with combined and preventive intravenous drug administration, which was reflected in a fibrous tissue formation decrease, reduced fractional-shortening decrease, and better antioxidant system performance. At the same time, it is important to note that the preventive administration of NR had a more significant protective effect on the animal organism as a whole. This was confirmed by better physical activity parameters and vascular bed conditions. Thus, the data obtained during the study can be used for further investigation into chronic doxorubicin-induced cardiomyopathy prevention and treatment approaches.

Neuropathic pain treatment with xenon

THE AIM: This study aimed to evaluate the effects of xenon on neuropathic pain during parapulmonal injections in the rat model. Xenon is a drug for inhalation anesthesia that is assumed to have an analgesic effect when administered parapulmonary (similar to nitrous oxide and cyclopropane) and can later be used as an alternative analgesic drug in patients with pain syndrome that is not controlled by standard methods.&#x0D; MATERIALS AND METHODS: The experiment used in vivo model of neuropathic pain by Bennet and Xie (1988) on rats with sciatic nerve transection. Additionally, a special scoring was adopted based on known behavioral changes of experimental animals (self-harm of limbs, neatness, activity, and bedding conditions). The control group was subcutaneously administered air daily for 5 days, and the experimental group received medical xenon at 40 ml/kg. The pain was assessed with the subcutaneous introduction of air and xenon in the experimental and control groups.&#x0D; RESULTS: Study results revealed that rats from the experimental group (xenon) showed fewer signs of neuropathic pain syndrome development compared to the control group (air).&#x0D; CONCLUSION: Therefore, parapulmonal injections of xenon showed a high analgesia effect in animal models of chronic neuropathic pain.

Comparison of Powder Flow Analysis by Particle Image Velocimetry with Discrete Element Method Simulation

To obtain an optimal powder bed condition for laser powder bed fusion (L-PBF), it is essential to clarify powder flow behaviors during the recoating process. In this work, the flow behaviors of Ti-6Al-4V powders were experimentally analyzed using a simple slope model by Particle image velocimetry (PIV) and were subsequently compared with the behaviors simulated using the similar model by discrete element method (DEM). The velocity of particles and the distribution were able to be obtained experimentally using PIV. In the DEM simulation, when the coefficient of restitution was increased, the angle between restituted particles and the slope and the average particle velocity were increased. Comparing those obtained by the DEM simulation, it was found that the velocity and distribution obtained by PIV analyses were close to those obtained by the DEM simulation at the coefficient of restitution of 0.3. These results suggest that the powder flow velocity analysis on the slope using PIV analyses is an effective method to validate the parameter of powder properties in DEM simulations.

Uncovering Basal Friction in Northwest Greenland Using an Ice Flow Model and Observations of the Past Decade

AbstractGlaciers move under the pull of gravity due to a combination of internal deformation (creep) and basal sliding. Basal sliding dominates ice motion in fast flowing areas, and an accurate description of sliding in ice flow models is therefore critical to adequately capture ice dynamics and its temporal evolution. However, there is currently no consensus on the exact form of basal friction law, as direct observations of basal properties remain limited. Using an ice flow model and observations of the past decade, we evaluate a variety of friction laws and determine their ability to reproduce the observed acceleration and mass loss of marine‐terminating glaciers in northwest Greenland. We find that friction laws that include an explicit dependence on the effective pressure better reproduce the observed acceleration and mass loss overall, with semi‐plastic basal laws describing some glaciers well. Our glacier‐scale model evaluation suggests heterogeneous bed conditions under northwest Greenland, which cannot be detected from the results of regional changes. Accounting for heterogeneous bed conditions, this region might contribute 15 mm to sea level rise by 2100, twice as much as predicted from models based on commonly used uniform bed conditions.

Study on Creep Characteristics of Water Saturated Phyllite

Phyllite is affected by its own bedding, stress environment and water-saturated conditions. There are great differences in its deformation and failure in engineering, and its creep characteristics are an important basis for evaluating the long-term stability of phyllite engineering. Therefore, this study carried out creep tests of water-saturated phyllite under different bedding angles and confining pressures, studied the coupling effect of factors that affect the creep characteristics of phyllite, and investigated and analyzed the deformation characteristics of a phyllite roadway support on site to provide basic support for phyllite roadway mine disaster control and collaborative mining research. The results showed the following: (1) When the bedding dip angle was 30~60°, under the control of the bedding, the sliding deformation along the bedding suddenly increased under the low-stress condition and the specimen did not undergo structural damage. It could continuously bear multi-level stress and generated creep deformation. In this case, a phyllite roadway should adopt the support method of combining flexibility and rigidity. (2) In the process of multi-stage stress loading, the creep instantaneous stress was directly proportional to the initial stress. When the stress was loaded to 50% of the failure strength, the instantaneous stress tended to be stable and maintained a linear, slightly increasing relationship with the stress. When the bedding angle was 30~60°, the creep deformation accounted for more than 50% of the total deformation. The bedding angles of 0° and 90° were dominated by the instantaneous strain during the stress loading process. For the flexible support of the roadway, the deformation caused by disturbance stress should be fully considered. (3) The uniaxial creep specimen mainly displayed compression shear tensile failure, with a small number of parallel cracks along the main fracture surface. The triaxial creep fracture mode changed to single shear failure. The confining pressure showed greater inhibition of the creep of the specimen with a bedding inclination of 0° and 90°. The strength design of the rigid support should refer to the original rock stress value of the roadway. The creep deformation and failure of the specimen with a bedding inclination of 30~60° were mainly controlled by the bedding. The included angle between the bedding dip angle and the maximum principal stress should be kept within 30~60° as far as possible in the roadway layout.

Effect of the Precursor and Synthesis Mode on the Properties of Hematite for the Preparation of Promoted Iron Oxide Catalysts

The fine crystal structure of hematite samples used to prepare potassium-promoted iron oxide dehydrogenation catalysts has been studied by X-ray diffraction and scanning electron microscopy. Samples of α-Fe2O3 were obtained under nonequilibrium conditions from several precursors under different thermolysis regimes. The most important characteristic of hematite, which determines the activity and selectivity of the catalyst based on it, is the fine crystal structure (TCS). The TCS of hematite determines the phase composition of the catalyst. The TCS of hematite is formed during the synthesis of hematite and is determined by the nature of the precursor, the temperature of sample synthesis, and the temperature gradient of the rate of removal of gaseous thermolysis products. The highest activity was demonstrated by a catalyst prepared on the basis of hematite with mosaic blocks of 70–90 nm, with a minimum concentration of SF due to half and quaternary dislocations. Such hematite was obtained by thermolysis of iron sulfate at 950 K under fluidized bed conditions and a low temperature gradient. Hematite from iron carbonate is not recommended for the synthesis of a catalyst due to the high concentration of low-temperature SF, which leads to the formation of catalytically inactive potassium β-polyferrite.