Increase In Water Content Research Articles

Experimental study on deformation characteristics of seasonal subgrade soil under dynamic load.

In Northwest China, the highway infrastructure often faces challenges due to the widespread presence of subgrade soil. This soil undergoes significant changes in performance under cyclic loading and freeze-thaw cycles. To effectively design and construct highways in these regions, it is crucial to understand the impact of various factors on the deformation characteristics and mechanical properties of subgrade soil. This study aims to investigate the influence of freeze-thaw cycles, water content, confining pressure, and loading rate on the deformation behavior and mechanical properties of subgrade soil under cyclic loading conditions. Experimental tests were conducted to analyze the deformation characteristics and mechanical properties of the subgrade soil. The test results revealed the following: 1) Dynamic loading leads to a noticeable decrease in the strength of subgrade soil, resulting in a softening effect on the stress-strain curve. The cumulative strain of the soil is positively correlated with the number of freeze-thaw cycles and water content, while negatively correlated with confining pressure. The final cumulative strain remains below 1%. 2) The failure stress of subgrade soil decreases exponentially with an increase in freeze-thaw cycles, dropping from 224.52 kPa to 196.76 kPa. 3) An increase in water content linearly decreases the failure stress of subgrade soil, ranging from 377.1 kPa to 151.5 kPa. 4) Confining pressure exhibits a linearly increasing relationship with the failure stress of subgrade soil, ranging from 151.6 kPa to 274.5 kPa. 5) The failure stress of subgrade soil demonstrates a linear increase with the loading rate, ranging from 200.46 kPa to 210.62 kPa. These findings provide valuable insights for the design and construction of highways in seasonal frozen areas. They also offer guidance for preventing and mitigating subgrade freeze-thaw issues in the future.

Experimental study on characterization of resilient modulus and prediction model of saline aeolian sand

The dynamic resilience characteristics of aeolian sand subgrade are influenced by salt content and water content, exhibiting significant stress dependence and anisotropy. The resilient modulus(MR) of aeolian sand represents the stress-strain nonlinearity under cyclic loading, serving as an important parameter for the design of aeolian sand subgrade in desert areas. In order to investigate the variation of MR of aeolian sand subgrade with salt content and water content under traffic loading, as well as the MR characteristics under these conditions, three types of aeolian sand samples with varying water content and four sulphate contents were prepared. The variation of MR of aeolian sand under different confining pressures and deviator stress levels, as well as the influences of water content and salt content, was studied through indoor dynamic triaxial testing. Based on the pattern of the fitting parameters of the benchmark model, a prediction model suitable for the MR of aeolian sand was constructed. The results indicate a rise in aeolian sand's MR with increasing deviator stress and confining pressure, with confining pressure having a more significant impact than deviator stress. With the increase in water content, the MR of aeolian sand decreases nonlinearly, and with the increase in salt content, it exhibits a wave-shaped trend of "increasing-decreasing-increasing," which is related to the dissolution state of sodium sulfate in the soil. Based on the experimental results, a prediction model of the MR of aeolian sand was established, derived from the benchmark model, which can reflect the influence of salt content and water content on the MR, introducing them as variables within the model.

Low-density granite-based geopolymer for well cementing: The role of burnt lime in enhancing early strength

In the pursuit of sustainable solutions within the oil and gas industry, the environmental and mechanical limitations of Ordinary Portland Cement (OPC) have led to the evaluation of more sustainable alternative materials for oilwell cementing applications. Particularly in shallow-depth cementing operations, where low-density slurries are essential to prevent formation breakdown, current solutions fall short in balancing environmental impact with the industry's performance requirements. Geopolymers, known for their reduced carbon footprint and comparable mechanical properties, have been seen as a promising alternative. However, increasing water content to lower the slurry density remains a challenge for geopolymers due to the weakening effect and prolonged reaction. The specific role of burnt lime (CaO) has the potential to enhance the early strength of low-density geopolymers yet remains under-explored for this particular case. This study aims to fill this gap by examining the effects of two different reactivities of CaO on a low-density granite-based geopolymer at low temperatures and investigate the potential of CaO to enhance the early strength of low-density geopolymers, aiming to provide a sustainable alternative to traditional cementing materials in oil well operation. The investigation consists of viscosity measurements, pumpability tests, and compressive strength evaluations. Additionally, isothermal calorimetry, TGA, XRD, and SEM were conducted to gain a deeper understanding of the behavior of each sample. Supplementary tests were conducted to evaluate the effect of varying CaO concentrations and the impact of mud contamination on the performance of low-density geopolymers. The investigation revealed that calcium oxide did not significantly impact the initial viscosity of the slurry however, it affects gelation and rate of the reaction. Short-term strength was shown to be affected by CaO at two different temperatures, yet negligible effects were seen in the long-term period for geopolymers with a high water-to-solid ratio. The findings suggest that CaO can significantly enhance the early strength of geopolymers, which are crucial properties for cementing operations in oil and gas wells. This could contribute to accelerate the possibility of geopolymers as a viable sustainable replacement for Portland cement especially in shallow and low-temperature well-cementing applications.

Experimental study on freezing temperature and its influencing factors of loess contaminated by heavy metals

This paper attempts to reveal the freezing temperature and its influencing factors of heavy metal-contaminated loess by adopting two cooling methods: fast and slow grading. As a result, Lanzhou loess was used as an experimental material to make polluted soil with varying heavy metal concentrations and initial water content. The pollutant elements included Zn, Ni, Cu, Cr, Cd, and Pb. The findings demonstrate that: 1) The slow cooling rate causes supercooling, jumping, and a progressive decrease in the temperature of the polluted soil. Different cooling methods have no obvious effect on freezing temperature. Furthermore, the freezing temperature of contaminated soil varies depending on its water content. The impact of increasing water content on freezing temperature is not evident; 2) The freezing temperature of loess decreases with the increase of heavy metal ion content. The freezing temperature of loess polluted by Zn, Ni and Cd ions decreased linearly with the increase of ion content. The influence of cations on the freezing temperature of loess is as follows: Zn2+> Ni2+> Cd2+> Cr3+> Pb2+> Cu2+. The influence order of anions is Cl− > SO42−; 3) The freezing temperature of loess containing heavy metal ions is about equal to the freezing temperature of the corresponding heavy metal solution plus the freezing temperature of loess itself. The freezing temperature of heavy metal-polluted loess follows the temperature superposition principle.

Tribological properties of diamond-like carbon films lubricated with water-emulsified engine oil

In this work, the tribological properties of two diamond-like carbon (DLC) films were investigated at different temperatures using water-engine oil emulsions as lubricants, considering emerging fuel systems such as hydrogen and ammonia. The results revealed that the friction coefficient of a-C film raised with the increasing water content at 80 °C. The friction coefficient of a-C:H film initially raised and then decreased with varying water fractions at different temperatures. Elevated temperature exacerbated the wear of both DLC films at high water contents. The most significant wear was observed for a-C film at 80 °C and a-C:H film at 50 °C. The a-C:H film exhibited more sensitive wear characteristics to water content than the a-C film. Surface analysis indicated that water-engine oil emulsions prevented the formation of phosphate tribo-film on steel friction pair for two DLC films but promoted the tribo-oxidation of steel pair sliding contact with a-C film, especially at higher temperatures. Distinct reactivities of two DLC films towards water molecules could affect the adsorption of lubricants on DLC surfaces, leading to their different friction and wear behavior. It suggests that the water-caused emulsification of lubricating oil will be a pivotal consideration in tribological applications of DLC films in future internal combustion engines.

Stability of Pure Biodiesel (B100), Biodiesel Mixture (B40), and Petroleum Diesel (B0) Due to Storage

Biodiesel is produced from synthetic ester compounds of vegetable and animal oils through a process of refining, bleaching, degumming, transesterification, and esterification. The quality and characteristics of the fuel are greatly influenced by the storage. The purpose of this research is to determine and analyze the effect of storage conditions on the physical and chemical changes of biodiesel (B100), biodiesel blend (B40), and petro diesel (B0). Experiment was conducted by storage fuels using glass bottle for 35 days arranged into four conditions based on cap and wrapping using aluminum foil, namely P1 (with cap, with wrapping), P2 (with cap, no wrapping), P3 (no cap, with wrapping), and P4 (no cap, no wrapping). Results showed that fuel quality decreases due to storage indicated by an increase in water content, density, acid number, and color parameters, as well as a decrease in the specific calorific value of all fuels. The condition of the storage container affected the changes the quality parameters. Based on its impact on fuel quality decline, the order of storage container conditions from the best is P1 (with cap, with wrap) > P2 (with cap, no wrap) > P3 (no cap, with wrap) > P4 (no cap, no wrap). Keywords: Biodiesel, Biodiesel blend (B40), Diesel fuel, Stability, Storage time.

Experimental study on the shear characteristics of frozen soil‐concrete interface under the constant normal stiffness

AbstractThe interaction between the structure and soil is a crucial factor in infrastructure stabilization in cold region engineering, both transversely and vertically. During interface deformation, the transverse action is reflected in the change of constraints, including normal stiffness, normal stress, and normal volume, while the vertical action is reflected in the change of shear properties. However, the study of different transverse constraints is not systematic, especially considering the normal stiffness and shear properties at different hydrothermal states. This study investigated the shear behavior of the interface between concrete and frozen soil under different normal stiffness, temperature, and water content using the interface direct shear test under temperature‐controlled conditions. The results show that with the increase in temperature and water content, the initial shear stiffness of the interface shear stress‐shear displacement curve gradually increases, and the interface shear strength gradually increases. Different normal stiffnesses have a small effect on the morphology of the interfacial shear stress‐shear displacement curve but significantly affect the peak shear strength. The peak shear strength increases significantly with the increase of normal stiffness, and this trend is more obvious with the decrease in temperature. The corresponding interfacial cohesion and friction angle also increases with the increase in normal stiffness.

Mechanical properties of teguline clay pellet mixtures during continuous oedometric compression

Clay pellet mixtures are generally compressed to improve their engineering performance. Deepening the comprehension of the mechanical properties of these mixtures in the complete compression process facilitates the benefit to the engineering design and their utilization. In this study, the effects of soil grain size distribution, water content and dry density on the mechanical properties and microstructure of Teguline clay pellet mixtures during a continuous oedometric compression process are explored. Three types of soil pellet mixtures, including mixture A (grain size ≤5 mm), mixture B (≤ 0.4 mm) and mixture C (2–5 mm), were prepared with different water contents of 7%, 8% and 12% respectively. Subsequently, continuous oedometeric compression was undertaken to explore their mechanical behaviours of the soil pellet mixtures. After that, the microstropic structures of the compacted pellet mixtures were investigated using mercury intrusion porosimetry (MIP). The results indicated that mixture A has a minimal initial packing density of pellet mixtures, while mixture C has a maximum one at the initial compression stage. After completion of compression, the compression curves of the pellet mixtures tended to converge uniformity at a semilogarithm coordinate as the vertical stress increased. All of the compression curves presented a concave shape at the plastic compression stage, which is significantly influenced by grain size distribution and water content. In contrast, the elastic compression and rebound behaviours are little affected by the grain size distribution and water content. As far as the microstructure is concerned, compacted samples prepared by mixture A or C presented a unimodal pore structure, while those by mixture B showcased a bimodal pore structure. In comparison with the unimodal pore distribution of the undisturbed stiff clay, the compacted samples displayed a pseudo-unimodal pore distribution because the inter-aggregate pores still existed. A double tangent method was proposed to determine the delimiting pore diameter of the pseudo-unimodal pore distribution curves and found that the delimiting pore diameter decreased with the increase of dry density and water content. Moreover, the inflexion point for the pore diameter of compacted samples prepared by coarse soil was larger than that of fine soil. Combining this work with previous research, it was found that the high compression of coarse soil easily causes the pseudo-unimodal shape, which is also impacted by water content and particle properties. This work could help deepen the understanding of the mechanical characteristics and microstructure of the stiff clay pellet mixtures during continuous oedometric compression.

Root tensile strength and suction-characteristic as indicators for screening species for slope stabilization in extreme climates

Root water potentials, essential for understanding drought tolerance and transpiration, can also influence root tensile strength, which is valuable for selecting plants for slope stabilization and erosion control in extreme wet and dry climates. This study investigated the relationships between root suction, water content, diameter and tensile strength of Cnidoscolus aconitifolius and Bougainvillea glabra to explore their potential for slope stabilization. Both species showed an increase in root water content and a decrease in suction with larger root diameter, despite their inherent difference in the tensile strength and suction relationship. The tensile strength versus suction plots clearly showed that Bougainvillea glabra can sustain higher load as root suction increases and is likely to perform better in extremely dry condition than Cnidoscolus aconitifolius. Observation of field performance indicated that this is the case which warrants further study on root suction for selecting species in stabilization of slopes in extreme climates.

Rising damp in heritage sites under urban expansion: A comprehensive case study of the Jinsha Earthen Site

Rising damp poses a significant threat to cultural heritage, yet its dynamics within actual heritage sites remain inadequately understood, particularly regarding its evolution and the impact of urbanization. The Jinsha Site, an earthen site from the Shang periods, is primarily composed of silt, with a layer of sand beneath and pebbles at the bottom, making it susceptible to rising damp. This study investigates the Jinsha Site as a case, monitoring soil water content and electrical conductivity, tracking changes in groundwater, precipitation, and river water levels, and investigating the relationship between urbanization and rising damp. The study aims to understand the process, causes, and influencing factors of rising damp and evaluate previous preservation strategies. The findings indicate that groundwater level in the sand layer trigger dampness, whereas the pebble layer exhibits dryness. Urban construction from 2006 to 2013 and 2014–2017 caused fluctuating groundwater levels, leading to repeated transitions between dryness and dampness at the site. Rainfall and river levels have negligible effect; even rainfall exceeding 100 mm (frequency <0.0056) only raises groundwater levels by approximately 1 m and increases water content by less than 2 % for a brief duration, typically less than half a month. The 2022 groundwater pumping strategy effectively maintained levels beneath the pebble layer (506 m), decreasing moisture by 12.71 % and conductivity by 0.27 dS/m. This study reflects on previous protection effortsand offers evidence-based strategies for heritage conservation amidst urban expansion.

Experimental study of the effect of crude oil water content on boilover fire

When a tank experiences a boilover fire, oil droplets splash, heat release rate and flame height increase, posing significant hazards. Water is a necessary condition for boilover to occur, but current research mainly focuses on boilover caused by water layer, neglecting the influence of water content inherent in crude oil on boilover phenomena. In this study, crude oil with a water content ranging from 0.26 % to 3 % was utilized, and a series of boilover fire experiments were conducted by varying the presence or absence of a water layer and the initial oil thickness and by carrying out a series of boilover fire experiments focusing on the effect of water content on the boilover phenomenon. The results indicate that emulsified crude oil has a droplet micro-explosion phase during the stable combustion stage. When no water layer is present, the boilover process duration is brief, and the transient injection effect is notable, with boilover intensity increasing with water content. Upon adding a water layer, emulsified water abbreviates the boilover onset time, diminishes the combustion rate, and promotes the formation of the hot zone. The upper and lower limit values of the hot zone temperature decrease with increasing water content, while the temperature difference remains essentially unaffected, remaining constant at about 50 °C. Boilover intensity exhibits a nonlinear relationship with increasing water content, peaking at 2 % water content. The pre-boilover burned mass ratio remains relatively stable, maintained between 12 % and 15 % across all working conditions. Both the splash range and maximum heat flux increase with initial oil layer thickness but show no significant change with water content. Moreover, the safety distance corresponding to the heat radiation threshold exceeds the splash distance, indicating that heat radiation hazards predominate. The results of this paper will help provide guidance for fighting emulsified crude oil fires.

The Role of Water Content and Binder to Aggregate Ratio on the Performance of Metakaolin-Based Geopolymer Mortars

Geopolymers are in many applications a perfect alternative to standard cements, especially regarding the sustainable development of green building materials. This experimental study therefore deals with the investigation of different factors, such as the water content and the binder to aggregate ratio, and their influence on the workability of fresh mortar and its mechanical properties and porosity on different size scales. Although increasing the water content improved the workability and flow behaviour of the fresh mortar, at the same time, a reduction in compressive strength in particular and a lesser reduction in flexural strength could be demonstrated. This finding can be attributed to an increase in capillary porosity, as demonstrated by capillary water uptake and mercury intrusion porosimetry measurements. At the same time, the increasing water content led to an improved deaeration effect (low air void content) and to initial segregation (see the µXCT measurements). An alternative approach to enhance the compressive and flexural strengths of the mortar specimens is optimization of the binder to aggregate ratio from 1 to 0.25. This study paves the way for a comprehensive understanding of the underlying chemistry of the geopolymerization reaction and is crucial for the development of sustainable alternatives to cementitious systems.

Humidity-Controlling Ceramic Bricks: Enhancing Evaporative Cooling Efficiency to Mitigate Urban Heat Island Effect

Passive evaporative cooling technology using the building envelope is a crucial measure to mitigate the urban heat island effect. This study aims to enhance the cooling efficiency of the surface of enclosure structures by utilizing volcanic ash, potassium–sodium stone powder, and silica-based mesoporous oxide (SMO) as primary materials. These components are incorporated into the ceramic brick production process to create innovative humidity-controlling ceramic bricks (HCCTs). This study extensively investigates the impact of SMO and the amount of applied glaze on the physical and mechanical characteristics of these HCCTs. Additionally, it examines the water absorption and evaporative cooling properties of the studied materials under optimal substitution conditions. Numerical calculations are used to determine the heat and moisture transfer properties of HCCTs. The results indicate that incorporating 2% SMO and applying 70 g/m2 of glaze results in a moisture absorption capacity of 385 g/m2 and a moisture discharge capacity of 370 g/m2. These conditions also yield a notable flexural strength of 15.2 MPa. Importantly, the HCCTs exhibit significantly enhanced capillary water absorption and water retention capabilities. Increased water absorption reduces surface temperature by 2–3 °C, maintaining the evaporative cooling effect for 20 to 30 h. It is also found that the temperature of HCCTs decreases linearly with increasing water content and porosity, while the temperature difference gradually decreases with thickness. Water migration in HCCTs with greater thickness is notably influenced by gravity, with water moving from top to bottom. Therefore, it is recommended that brick thickness does not exceed 15 mm.

Study on the influence of different factors on the performance of centrifugal supergravity oil-water separator

As the development of oil fields progresses, an increasing number of fields are entering high water-cut stages.Onsite oil-water separation and wastewater reinjection are crucial for reducing water treatment loads and energy consumption in crude oil transportation. Traditional oil-water separators suffer from issues such as large size and low separation efficiency. Therefore, this paper investigates a highly efficient centrifugal supergravity oil-water separator. Numerical simulations examined the impact of flow parameters, structural parameters, and physical properties on the separator’s flow field and performance. The research findings reveal that the oil-water separation efficiency decreases with an increase in water content. As the inlet flow increased, the oil content at the water outlet continuously rose. With an increase in motor speed, the separation efficiency initially increased and then stabilized. Within the simulated range, the number of blades was positively correlated with the separation effect, while the blade ripple radius, oil density, and viscosity were negatively correlated with the separator's effectiveness. An increase in orifice diameter caused fluctuations in the separation effect and the oil content at the water outlet.

Proton Transport in Aqueous Phosphoric, Sulfuric, and Nitric Acids: An Ab Initio Study

Proton transport plays a pivotal role in various electrochemical processes and technologies. It occurs through two primary mechanisms: the vehicular mechanism where a protonic defect moves with the aid of a molecular entity; and the ‘Grotthuss mechanism’ where a proton diffuses by being transferred between host molecules via hydrogen bonds. Recently, results from ab initio molecular dynamics (AIMD) simulations combined with dielectric spectroscopy, light, and quasielastic neutron scattering revealed that protons in neat phosphoric acid indeed move by surprisingly short jumps (~0.5-0.7 Å)1,2. In the present work, we continue to delve into the solvation and transport of protons in aqueous acid using AIMD simulations.Aqueous systems of phosphoric acid (PA), sulfuric acid (SA), and nitric acid (NA) were examined at two different ratios of acid to water 1:1 and 1:3 to understand the similarities and differences in proton transport mechanisms in these aqueous acids. The solvation structure of H3O+ in these acid solutions resembles that in the slightly acidic water but varies in the strength of hydrogen bonds formed with the acid molecules. Our results demonstrate that the strong hydrogen bonds between the PA molecules are slightly influenced by the presence of water molecules. Furthermore, the simulations reveal that H3O+ diffuses significantly faster in the aqueous PA systems than in the solutions of either SA or NA due to the assistance of PA molecules. Proton transfer events in the process of H3O+ transport show that the acid molecule can accept a proton from H3O+, either enhancing the H3O+ diffusion by shuttling a proton through a collective proton hopping or impeding it via rattling. The shuttling event significantly contributes to the H3O+ diffusion in aqueous PA, rarely occurring in the aqueous SA and never in the aqueous NA. Moreover, decomposition of H3O+ diffusion into vehicular and structural diffusion components indicates that the higher diffusion in aqueous PA is primarily due to the structural mechanism aided by the PA molecules. In the aqueous NA systems, however, the vehicular diffusion is dominant at low water contents, while increasing water content enhances the structural diffusion via connected hydrogen bonds between the water molecules. These findings shed light on the role of acid molecules in proton transport within their aqueous solutions, advancing our understanding of these fundamental mechanisms.

Microscopic Characterization of Deformation Behavior during Kerogen Evolution: Effects of Maturity and Skeleton Moisture Content.

The CH4 storage and seepage capacity of shale kerogen are the main controlling factors of the natural gas production rate, and the porosity and permeability of kerogen are greatly affected by kerogen deformation. Therefore, the study of the deformation rule and CH4 adsorption characteristics of kerogen at different maturities and skeleton moisture contents has an important impact on the proper understanding of the development potential of shale gas reservoirs. In this paper, kerogen maturity (II-A, II-B, II-C, and II-D) and skeleton moisture content (0.0, 0.6, 1.2, 1.8, and 2.4 wt %) were considered. The deformation of kerogen, the adsorption of CH4 after deformation, and the quadratic deformation induced by CH4 were studied by using Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD). The results show that the kerogen volume strain increases with increasing skeleton moisture content, following the order II-A < II-B < II-C < II-D for the same moisture content. The density of the kerogen matrix decreases, and porosity increases with rising moisture content. The void fraction of immature kerogen decreases with increasing water content, while the opposite is true for postmature kerogen. The presence of skeleton moisture decreases the CH4 adsorption capacity of immature kerogen and increases the CH4 adsorption capacity of postmature kerogen. The chemical structure of immature kerogen is relatively soft, making its volume more affected by CH4 adsorption compared with postmature kerogen. In the same water environment, postmature kerogen has greater CH4 storage, diffusion, and seepage capacity compared to those of immature kerogen, suggesting that reservoirs with high organic matter maturity should be prioritized for development.

Understanding and Controlling Reactivity Patterns of Pd1@C3N4-Catalyzed Suzuki-Miyaura Couplings.

Using heterogeneous single-atom catalysts (SACs) in the Suzuki-Miyaura coupling (SMC) has promising economic and environmental benefits over traditionally applied palladium complexes. However, limited mechanistic understanding hinders progress in their design and implementation. Our study provides critical insights into the working principles of Pd1@C3N4, a promising SAC for the SMC. We demonstrate that the base, ligand, and solvent play pivotal roles in facilitating interface formation with reaction media, activating Pd centers, and modulating competing reaction pathways. Controlling the previously overlooked interplay between base strength, reagent solubility, and surface wetting is essential for mitigating mass transfer limitations in the triphasic reaction system and promoting catalyst reusability. Optimum conditions for Pd1@C3N4 require polar solvents, intermediate base strength, and increased water content. Our investigations reveal that high selectivity requires minimizing competitive coordination of bases and phosphine ligands to the Pd centers, to avoid homocoupling and alternative reductive elimination mechanisms giving rise to phosphonium side-products. Furthermore, in situ XAS investigations probing electronic structures and coordination environments of Pd sites further rationalize the base and ligand coordination, confirming and expanding upon previous computational hypotheses for Pd1@C3N4. This understanding allows for designing a more selective ligand-free reaction pathway using the solvent and base to modulate the chemical environment of the active sites. We highlight the importance of environment-compatible surface tension, the creation of coordinatively available active sites, and the stabilization of partially reduced Pd centers, emphasizing the importance of mechanistic studies to advance the design of SACs in organic liquid phase reactions.

Effects of curdlan on the quality of frozen steamed bread: quality changes, water state and starch crystallinity

SummaryThe purpose of the study was to explore the effects of curdlan on the textural and sensory qualities of frozen steamed bread (FSB), as well as water state and starch properties during freezing. The results showed that incorporation of curdlan improved the springiness and resilience, while it reduced the hardness and chewiness of FSB. The quality deterioration of FSB was largely caused by the growth and recrystalisation of ice crystals. However, incorporation of curdlan mitigated this adverse impact by regulating water state. Specifically, it increased water content, inhibited water migration, and significantly decreased freezable water content. Additionally, curdlan also decreased starch relative crystallinity, which hindered its retrogradation and thus maintained the overall quality of FSB. Notably, inclusion of 0.5% curdlan exhibited optimal effectiveness in improving quality as evidenced by the highest sensory score obtained.

FTIR Monitoring of Polyurethane Foams Derived from Acid-Liquefied and Base-Liquefied Polyols.

Polyalcohol liquefaction can be performed by acid or base catalysis, producing polyols with different properties. This study compared the mechanical properties of foams produced using polyols from liquefied Cytisus scoparius obtained by acid and base catalysis and using two different foam catalysts. The differences were monitored using FTIR analysis. Acid-catalyzed liquefaction yielded 95.1%, with the resultant polyol having an OH index of 1081 mg KOH/g, while base catalysis yielded 82.5%, with a similar OH index of 1070 mg KOH/g. Generally, compressive strength with dibutyltin dilaurate (DBTDL) ranged from 16 to 31 kPa (acid-liquefied polyol) and 12 to 21 kPa (base-liquefied polyol), while with stannous octoate (TIN), it ranged from 17 to 42 kPa (acid) and 29 to 68 kPa (base). Increasing water content generally decreased the compressive modulus and strength of the foams. Higher water content led to a higher absorption at 1670 cm-1 in the FTIR spectrum due to the formation of urea. Higher isocyanate indices generally improved compressive strength, but high amounts led to unreacted isocyanate that could be seen by a higher absorption at 2265 cm-1 and 3290 cm-1. DBTL was shown to be the best foam catalyst due to higher trimer conversion seen in the spectra by a higher absorption at 1410 cm-1. Acid- and base-derived polyols lead to different polyurethane foams with different FTIR spectra, particularly with a higher absorption at 1670 cm-1 for foams from acid-derived liquefaction.

Study on characteristics of the resistivity parameter and its coupling model of Chazangcuo copper-lead-zinc deposits based on microscopic analysis

Abstract The resistivity exploration has made a great contribution to prospecting at the macro level, but the resistivity exploration at the micro level is relatively weak. In this paper, the corresponding resistivity is analyzed through a geochemical element test, temperature and pressure test, water content and porosity test, and the resistivity parameter model of the rock and ore is established based on the response surface. The main conclusions and understandings obtained are as follows: with the increase of Cu-Pb-Zn content, the rock-ore resistivity shows an obvious decreasing trend, with sphalerite resistivity (72.8×10−2 Ω·m) &gt; pyrite resistivity (32.5×10−2 Ω·m) &gt; galena resistivity (76.5×10−3 Ω·m) &gt; chalcopyrite (11.3×10−3 Ω·m). The resistivity increases with the temperature, showing a quadratic term function trend increases. The resistivity decreases with the increase of pressure, decreasing rapidly at the beginning of loading and gradually slowing down. The resistivity decreases rapidly with the increase of water content and porosity in an exponential function trend. The degree of influence of four factors, temperature, pressure, porosity, and water content, on the resistivity of the ore samples, is the order of water content, porosity, pressure, and temperature. The coupled model of resistivity of Cu-Pb-Zn ores established by multivariate quadratic regression analysis is more reliable, and the predicted value of rock and ore resistivity is more consistent with the test data.