Core Hole Research Articles

A portable microfluidic device for thermally controlled granular sample manipulation.

Effective granular sample manipulation with a portable and visualizable microfluidic device is significant for lots of applications, such as point-of-care testing and cargo delivery. Herein, we report a portable microfluidic device for controlled particle focusing, migration and double-emulsion droplet release via thermal fields. The device mainly contains a microfluidic chip, a microcontroller with a DC voltage control unit, a built-in microscope with a video transmission unit and a smartphone. Five microheaters located at the bottom of the microfluidic chip are used to unevenly heat fluids and then induce thermal buoyancy flow and a thermocapillary effect, and the experiments can be conveniently visualized through a smartphone, which provides convenient sample detection in outdoor environments. To demonstrate the feasibility and multifunctionality of this device, the focusing manipulation of multiple particles is first analyzed by using silica particles and yeast cells as experimental samples. We can directly observe the particle focusing states on the screen of a smartphone, and the particle focusing efficiency can be flexibly tuned by changing the control voltage of the microheater. Then the study focus is transferred to single-particle migration. By changing the voltage combinations applied on four strip microheaters, the single particle can migrate at predetermined trajectory and speed, showing attractiveness for those applications needing sample transportation. Finally, we manipulate the special three-phase flow system of double-emulsion drops in thermal fields. Under the combined effect of the thermocapillary effect and increased instability, the shell of double-emulsion droplets gradually thins and finally breaks, resulting in the release of samples in inner cores. The core release speed can also be flexibly adjusted by changing the control voltage of the microheater. These three experiments successfully demonstrate the effectiveness and multifunctionality of this thermally actuated microfluidic device on granular manipulation. Therefore, this portable microfluidic device will be promising for lots of applications, such as analytical detection, microrobot actuation and cargo release.

Shell-dependent photofragmentation dynamics of a heavy-atom-containing bifunctional nitroimidazole radiosensitizer.

Radiation therapy uses ionizing radiation to break chemical bonds in cancer cells, thereby causing DNA damage and leading to cell death. The therapeutic effectiveness can be further increased by making the tumor cells more sensitive to radiation. Here, we investigate the role of the initial halogen atom core hole on the photofragmentation dynamics of 2-bromo-5-iodo-4-nitroimidazole, a potential bifunctional radiosensitizer. Bromine and iodine atoms were included in the molecule to increase the photoionization cross-section of the radiosensitizer at higher photon energies. The fragmentation dynamics of the molecule was studied experimentally in the gas phase using photoelectron-photoion-photoion coincidence spectroscopy and computationally using Born-Oppenheimer molecular dynamics. We observed significant changes between shallow core (I 4d, Br 3d) and deep core (I 3d) ionization in fragment formation and their kinetic energies. Despite the fact, that the ions ejected after deep core ionization have higher kinetic energies, we show that in a cellular environment, the ion spread is not much larger, keeping the damage well-localized.

Integrating random forest and morphological spatial pattern analysis for predicting future land surface temperature dynamics: insights from urbanizing Saudi Arabia

In the face of rapid urbanization in Saudi Arabia, understanding the impact of landscape changes on land surface temperature (LST) is crucial for sustainable urban planning. This study assesses the influence of landscape morphology on LST and predicts future LST changes. A multi-temporal land use and land cover (LULC) analysis using random forest (RF) quantified urban expansion and its ecological impacts. Accuracy assessment using the kappa coefficient illustrated the precision of the classification techniques. Morphological Spatial Pattern Analysis (MSPA), developed in Python, analyzed the structural evolution of urban areas, vegetation and exposed rocks. Polynomial regression models established the relationship between landscape morphology and LST and predicted future temperature trends. Results for Asir show a significant improvement in accuracy of the LULC models over three decades, with overall accuracy increasing from 89.99% in 1990 to 91.72% in 2020. The bootstrapping trend analysis showed an urban expansion with a positive slope of 9.27 and a decline in water bodies with a negative slope of −0.03. The MSPA analysis reflected a significant urban expansion, with the core area growing from 45.19 km2 in 2001 to 230.33 km2 in 2021. The vegetated areas showed resilience and dynamic connectivity despite slight reduction and fragmentation. The polynomial regression predicted an increase in future average LST by 2030, with urban core areas reaching 58.47 °C, vegetated cores 42.19 °C and exposed rock cores 55.79 °C. These results highlight the link between urban expansion and LST rise and make the case for integrating green infrastructure and cooling strategies into urban development.

Main minerals of the Araxá alkali-carbonatite complex, Minas Gerais State, Brazil

The Araxá alkali-carbonatitic complex is a significant source of niobium and phosphate and accounts for approximately 75% of global niobium production. The complex contains magmatic niobium ore minerals, such as natrium-pyrochlore and calcium-pyrochlore, and hydrothermal niobium ore minerals in the form of kenopyrochlore and natrium-pyrochlore. The magmatic micas in the complex are tetraferriphlogopites that exhibit Mg-rich cores surrounded by one or two rims of tetraferriphlogopites formed by hydrothermal alteration. These rims have lower IVAl and Mg apfu (atom per formula unit) values but higher IVFe3+ and Fe2+ contents than the original phlogopite. Microphlogopitite dikes that formed during several episodes of magmatism between 83.48 and 77.4 Ma contain tetraferriphlogopites, phlogopite, eastonite, biotite, and annite-siderophyllite. These micas exhibit variations in Mg2+ and Fe2+ concentrations owing to the magmatic differentiation and subsequent hydrothermal alteration, resulting in rims with higher Mg and lower Fe2+ concentrations than the mica core. The Araxá complex also contains magmatic magnetite that has been further altered by hydrothermal processes, resulting in the formation of ilmenite and the oxidation and crystallization of titaniferous hematite. Magnetite within the microphlogopitites displays variations in the concentrations of Fe3+ and Ti, likely owing to the timing of the intrusion of the microphlogopitites into the Araxá complex. The degree of oxidation of the oxidized ilmenite of the Araxá complex varies based on the intrusions, which occurred before or during hydrothermal activity. Apatite is concentrated in carbonatites, which form a ring around the core of the complex, and disseminated in phlogopite-rich rocks hosting norsethite carbonatite veins in the center of the complex. The apatite in the core rocks exhibits complex zonation with unexpected changes in Ca, P, and Sr concentrations. Apatite in the carbonatite ring was generated during the differentiation of the carbonatite magma, whereas that in the core rocks exsolved from the phosphorus-saturated carbonatite magma (in press). The carbonate minerals dolomite, norsethite, and calcite exhibit compositions grouped around their end-members, suggesting that they formed during different stages of magmatic source differentiation. Strontium differentiation occurs in the magmas corresponding to each endmember, and carbocernaite is exsolved from the Sr-saturated crystals, thus forming micro-inclusions in some carbonate crystals that have been displaced by late-magmatic hydrothermal fluids.

Chlorinated ethenes characterization using high-resolution rock core analysis in a weathered crystalline rock aquifer in São Paulo, Brazil

Chlorinated ethenes characterization using high-resolution rock core analysis in a weathered crystalline rock aquifer in São Paulo, Brazil

A Comparative Analysis of Mechanical Properties Between Granite and Basalt Rock Core Samples

Structural failure occurs when a load-bearing component of a structure fails to support and transfer loads to another element, leading to a breakdown in the performance of the materials in that structural component. The potential for structural failure is influenced by various variables, emphasizing the importance of understanding the behavior and parameters specific to rocks and soils in construction. In order to prevent failures in construction, engineers must possess a fundamental geological knowledge of rocks during the design process, recognizing the limitations of this construction material. Consequently, it is imperative to conduct tests to determine the precise strength of the rock being utilized. This study focused on granite and basalt, employing the Portable Ultrasonic Non-Destructive Digital Indicating (PUNDIT) test, Uniaxial Compressive Strength (UCS) test, and Brazilian test. The selected rock samples adhered to a diameter and thickness ratio of 1:2 or 2:1, depending on the specific test to be conducted. Density, compressive strength, and tensile strength of the rock samples were evaluated following the guidelines provided by the American Society for Testing and Materials (ASTM). The findings revealed that basalt exhibited higher density, compressive strength, and tensile strength compared to granite, with variations in results ranging from 13% to 40%.

Critical Condition of the Depth Limit of Oil Accumulation of Carbonate Reservoirs and Its Exploration Significance in the Lower Ordovician of the Tazhong Area in the Tarim Basin

Critical Condition of the Depth Limit of Oil Accumulation of Carbonate Reservoirs and Its Exploration Significance in the Lower Ordovician of the Tazhong Area in the Tarim Basin

Establishment of temperature‐strength response prediction model of supramolecular gel temporary plugging agent by response surface method analysis

AbstractIn this study, response surface methodology (RSM) was applied to optimize the preparation of a supramolecular gel temporary plugging agent. According to single‐factor experiments, results showed that the gelling temperature was preset at 100°C, and the gelling strength reached the maximum. Three‐factor RSM model prediction was carried out to explore the determination coefficient (R2) of the gelling temperature and strength and their degree of influence, and the predicted results were verified by experiments. No difference was found between the experimental results and the predicted results, indicating that this model could be used to optimize the preparation of DMF supramolecular gels. DSC, FT‐IR, XRD, and SEM were used to investigate the formation mechanism of the optimized supramolecular gel temporary plugging agent (CD‐Da), and its compatibility, stability, rheology, and plugging performance were evaluated. Experimental results showed that CD‐Da has the characteristics of good injectability in low‐permeability rock cores, strong plugging capacity, self‐breaking, and less damage to the formation. Therefore, this study not only provides a stable and efficient supramolecular gel plugging agent for tight oil and gas reservoirs, but also establishes a prediction model between each component and supramolecular gel, providing a new optimization method for the preparation of supramolecular gel.

Auger spectroscopy beyond the ultra-short core-hole relaxation time approximation

We present a time-dependent computational approach to study Auger electron spectroscopy (AES) beyond the ultra-short core-hole relaxation time approximation and, as a test case, we apply it to the paradigmatic example of a one-dimensional Mott insulator represented by a half-filled Hubbard chain. The Auger spectrum is usually calculated by assuming that, after the creation of a core-hole, the system thermalizes almost instantaneously. This leads to a relatively simple analytical expression that uses the ground-state with a core-hole as a reference state and ignores all the transient dynamics related to the screening of the core-hole. In this picture, the response of the system can be associated to the pair spectral function. On the other hand, in our numerical calculations, the core hole is created by a light pulse, allowing one to study the transient dynamics of the system in terms of the pulse duration and in the non-perturbative regime. Time-dependent density matrix renormalization group calculations reveal that the relaxation process involves the creation of a polarization cloud of doublon excitations that have an effect similar to photo-doping. As a consequence, there is a leak of spectral weight to higher energies into what otherwise would be the Mott gap. For longer pulses, these excited states, mostly comprised of doublons, can dominate the spectrum. By changing the duration of the light-pulse, the entire screening process can be resolved in time.

Influence of rock properties on thrust and torque during rock coring operations a case study

The most important parameters for rock strength evaluations in excavation, mining, and mechanical engineering projects are the uniaxial compressive strength, Brazilian tensile strength, density, abrasivity, and impact strength index. To estimate these parameters, several laboratory investigations and nondestructive methods were proposed. The possibility of using time-saving models for predicting uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), density, abrasivity, and impact strength index was investigated because of the difficulties in core specimen preparation. The novelty of this investigation was the prediction of rock properties using thrust and torque generated during rock coring operations. For this purpose, drilling experiments were conducted on seven different types of rock samples using a computer numerical control drilling machine. Based on the statistical analysis, simple linear regression equations were proposed for estimating rock properties, such as compressive strength, tensile strength, density, abrasivity, and impact strength index. The coefficient of determination (R 2), values obtained for thrust are 90.8, 93.3, 80.7, 87.6, and 96.3%, for compressive strength, tensile strength, density, abrasivity, and impact strength index, respectively. Whereas the corresponding torque values are 84.9, 83.9, 95.9, 81.6, and 82.6%. The developed models can be used in the exploration and excavation developments for the prediction of rock properties.

3D Carbonate Digital Rock Reconstruction by Self-Attention Network and GAN Structure

Amidst the rapid advancements in digital technology, the pursuit of simulating geologic and mineralogic samples in a digital domain has garnered considerable attention, becoming a linchpin in modern earth science and petrological research. This manuscript intricately explores the deployment of state-of-the-art generative models for the meticulous reconstruction of digital rock core samples. Central to this investigation was the innovative incorporation of the self-attention mechanism—a pioneering endeavor in the domain of digital rock core studies. By harnessing the prowess of this sophisticated model, we endeavored to produce samples that echo the nuanced geological and mineralogical attributes emblematic of authentic rock specimens. Distinguishing our approach, the generative architecture, bolstered by the self-attention mechanism, demonstrated unparalleled proficiency in replicating quintessential rock features, ranging from porosity and granular texture to contiguous core sequences. Additionally, the idiosyncrasies of carbonate rocks were meticulously captured, highlighting phenomena like dissolution. Empirical evaluations, rooted in stringent statistical analyses, attested to the model’s capability to generate outputs that resonate closely with genuine samples. This exploration not only amplifies the potential applications of our proposed model in geoscientific endeavors but also signals a transformative stride in digital rock physics, emphasizing the harmonious amalgamation of innovative computational models with profound geological insights.

Effect of Core Hole Diameter on Tensile and Fatigue Properties of the Helically Formed Internal Thread in AlSi10MnMg Cast Alloys

The manufacturing of internal thread using the helical thread forming process (Punch Tap) as a novel high-performance manufacturing technology provides high productivity by reducing the tool path, which can save manufacturing time up to 75% compared to the conventional thread forming process. For instance, cast gearboxes in the transport sector consisting of numerous internal threads can benefit from this manufacturing method to realize detachable joints. While the required core hole diameter for conventional (cut) tapping depends on the thread dimension, this diameter depends either on the material properties for the thread forming process. The proper core hole diameter according to material flow possibility enables forming of complete thread profiles, which can consequently enhance the mechanical properties of the thread. This study aims to analyze the effect of the core hole diameter on the quality of the formed threads in AlSi10MnMg cast profiles. M6 threads were formed into the pre-drilled core holes with two different diameters. CT-scan analysis indicated that reducing the core hole diameter decreases the inner volume of the formed internal thread, which is justified by better material flow and complete forming of the thread profiles. Adaptation of the manufacturing parameters according to the material properties enhanced the geometry of the formed thread profiles. This enhancement increased the tensile and fatigue strengths of the detachable joints by subjecting the four initially formed threads at the top of manufactured nuts to the static and cyclic loads.

Synthesis of cost-effective Si-CQD for effective oil separation from core rock

Nanomaterials (NMs) based on carbon are suitable candidates for separating oil from core rock. Nowadays, the application of carbon-based NMs to enhanced oil recovery (EOR) is far less. The production of NMs based on carbon (water-wet) is of great importance due to the high recovery they create in reservoirs. The purpose of this study was to change the wettability of oil-wet (OW) carbonate rock (CR) towards water-wet (WW) conditions using cheap synthetic materials. In this regard, the effect of three quantum carbon dots (CQDs) on saltwaters has been used. The CQDs were synthesized by hydrothermal procedure and tetraethyl orthosilicate (TEOS) was used as the initial source of carbon. In this regard, Si-CQDs indicated great colloidal sustainability in saltwaters solutions. Therefore, to determine the morphological characteristics and structure of the synthesized NMs, Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR) were done. The stability of NMs was investigated using the zeta potential (ZP). The new compound showed acceptable results at a very low concentration of 100 ppm. The findings indicated that the nanofluid (100 ppm Si-CQDs + Seawater (SE)) reduced the interfacial tension value from 23.34 mN/m to 7 mN/m. Also, the results showed the solution of SE + 100 ppm Si-CQDs improved the oil recovery by 24 % and 23 %. Generally, this paper opens the door for the development of carbon-based NMs with the ability to absorb sediments in the porous media of the reservoir for the efficient separation of oil from core rock. Generally, our analysis supports the use of Si-CQDs as an efficient and economical additive for further oil recovery in carbonate reservoirs.

Inverse Modeling of Core Flood Experiments for Predictive Models of Sandstone and Carbonate Rocks

AbstractField‐scale observations suggest that rock heterogeneities control subsurface fluid flow, and these must be characterized for accurate predictions of fluid migration, such as during CO2 sequestration. Recent efforts characterizing multiphase flow in heterogeneous rocks have focused on simulation‐based inversion of laboratory observations with X‐ray imaging. However, models produced in this way have been limited in their predictive ability for heterogeneous rocks. We address the main challenges in this approach through an algorithm that combines new developments: a 3‐parameter capillary pressure model, spatial heterogeneity in absolute permeability, improved image processing to capture more experimental data in the calibration, and the constraint of history match iterations based on marginal error improvement. We demonstrate the improvements on two sandstones and three carbonate rocks, with varying heterogeneity, some of which could not be previously modeled. The algorithm results in physically representative models of the rock cores, reducing non‐systematic error to a level comparable to the experimental uncertainty.

Gas transport model in pore heterogeneous bedded salt rock: Implications for tightness evaluation of salt cavern gas storage

To address the gas flow behaviors in bedded salt rock, an apparent permeability model considering Knudsen diffusion, pore surface diffusion, and pore heterogeneity was presented. The evolutions of gas permeability and gas flow behaviors with pressure were hinted by a gas seepage experiment carried out for model verification. The results show that the new apparent permeability model could accurately invert the seepage behaviors in the cores of salt rock and interlayer, with an average error of 2.39% and 1.22% for helium and nitrogen, respectively. When the pore pressure is 0.5 MPa, the permeability contribution of Knudsen diffusion accounts for 82.35% of the apparent permeability. When the pore pressure is higher than 1.24 MPa, the permeability of Knudsen diffusion is lower than that of viscous flow. Once the gas pressure is higher than 2 MPa, the permeability contribution of Knudsen effect is basically equal to 0. A special focus was given to the different gases in salt cavern gas storage, which indicated that the leakage ratio of hydrogen is the highest, followed by methane, and helium is the lowest, with 7.27%, 5.76%, and 4.58%, respectively during the 30 years operation period. This work could add further insights into the gas flow behaviors in the pore heterogeneous salt rock and be employed for tightness evaluation of salt cavern gas storage and pillar width design of adjacent salt caverns.

Petrological insights into connections between the S- and I-type magmatic associations in metamorphic core complexes: a case study of the Çataldağ metamorphic core complex (NW Turkey)

As one of the Cordilleran-type metamorphic core complexes in the western Anatolian extensional province and the broader Aegean region, the Çataldağ metamorphic core complex is composed of a granite-gneiss-migmatite complex and a synkinematic pluton, bounded by a detachment fault zone. The plutonic rocks within the footwall of the Çataldağ metamorphic core complex consist of Eo-Oligocene anatectic S-type leucogranites associated with gneiss-migmatite complex forming the core rocks and an I-type synkinematic pluton that emplaced into the core rocks in the Early Miocene. This paper presents the petrography, mineral chemistry, major-trace element geochemistry, and Sr-Nd-Pb isotope compositions of the Çataldağ I-type synkinematic pluton. It discusses the magma source evolution from the Eo-Oligocene to the Early Miocene and their relations to the Çataldağ metamorphic core complex formation by comparing two contrasting granitic associations from a petrological perspective. The Çataldağ I-type synkinematic pluton primarily comprises porphyritic granodiorite, granite, and peripheral rocks including evolved granite and pegmatite dikes. Thermobarometry calculations estimate crystallisation conditions of approximately 795 °C at 1–2 kbar (averaging 1.5 kbar), corresponding to a shallow crustal magma chamber (⁓5 km deep). The pluton is metaluminous to slightly peraluminous and of a high-K calc-alkaline character. The 87Sr/86Sr(i) and εNd values of the studied samples range from 0.70684 to 0.70772 and from −6.1 to −2.3, respectively. Pb isotopic compositions are 18.74–19.29 for 206Pb/204Pb, 15.69–15.78 for 207Pb/204Pb, and 38.89–39.39 for 208Pb/204Pb. Geochemical modelling shows that a large amount of metasomatised lithospheric mantle-derived melt component (up to 70%) and a minor crustal component (<50%) contributed to the source region of the magma. The combination of isotopic data and thermodynamic modelling suggests that the compositional variations within the pluton were primarily the result of open system processes, predominantly the assimilation of crustal rocks with a dominance of fractional crystallisation. The Sr-Nd-Pb isotopic signatures and trace element characteristics of I-type pluton, as well as their comparisons with those of S-type leucogranites within the Çataldağ core complex, indicate heterogeneous magma sources, evolving from crust-dominated to mantle-dominated magma from Eo-Oligocene to the early Miocene, reflecting mantle upwelling beneath NW Anatolia. We infer that the long-lived, mantle-driven Eocene plutonic activity that preceded the development of core complexes may have led to thermal weakening, melting, and crustal flow in the lower-middle crust beneath NW Anatolia, facilitating the formation of the granite-gneiss-migmatite complex during the incipient phase of extension in the Eo-Oligocene. Coinciding with the rapid exhumation of the S-type granite and migmatite complex, the formation and emplacement of I-type synkinematic pluton along the detachment fault zone of the Çataldağ core complex were developed as a result of asthenospheric upwelling driven by lithospheric removal processes. This inferred lithospheric removal was triggered by Hellenic slab rollback affecting the entire western Anatolia since the Oligocene. The transition from S- to I-type granites observed in the Çataldağ core complex and other Aegean massifs may indeed be a manifestation of the intensity or accumulation of this crustal extension.

Machine learning approach to predicting the macro-mechanical properties of rock from the meso-mechanical parameters

The determination of fundamental rock mechanical properties, uniaxial compression strength (UCS) and elastic modulus (E), constitutes a pivotal facet of rock engineering design. However, deriving these properties directly from standard laboratory tests on rock core samples can be challenging, especially when dealing with deep high-stress rock formations and weak fractured strata. Thus, it is crucial to establish a cost-effective and practical approach for predicting the macro-mechanical properties of rocks in situ. In this study, a machine learning approach was proposed to predict UCS and E by upscaling meso-mechanical parameters at particle scale in low-porosity crystalline rocks. To expand the correlation database of rock meso-macro mechanical properties, the meso-mechanical parameters, including the fracture toughness, tensile strength of the rock crystal interface, and the elastic modulus of rock crystal, were accurately measured, using a newly designed mechanical apparatus and a nanoindentation device. The grain-based models implemented in the combined finite discrete element method (FDEM-GBM) were developed based on these experimental results, and their reliability was validated though standard tests. Subsequently, a database, including 225 groups of data, was established using the numerical method. Five machine learning algorithms were applied to develop prediction models for UCS and E through data training in the database. Excellent performance improvement was achieved through the application of the grid-search method. The results indicate the optimized kernel ridge regression (KRR) and gaussian process regression (GPR) models demonstrated excellent performance with relative average errors of 4.9% and 1.1% in predicting UCS and E, respectively. Finally, the predicted values of UCS and E were compared with the experimental results, validating the feasibility of the optimized KRR and GPR models.

Experimental Study on SiO2 Nanoparticles-Assisted Alpha-Olefin Sulfonate Sodium (AOS) and Hydrolyzed Polyacrylamide (HPAM) Synergistically Enhanced Oil Recovery

The purpose of this study is to investigate the use of SiO2 nanoparticles in assisting with surfactants and polymers for tertiary oil recovery, with the aim of enhancing oil recovery. The article characterizes the performance of SiO2 nanoparticles, including particle size, dispersion stability, and zeta potential, evaluates the synergistic effects of nanoparticles with alpha-olefin sulfonate sodium (AOS) surfactants and hydrolyzed polyacrylamide (HPAM) on reducing interfacial tension and altering wettability, and conducts core flooding experiments in rock cores with varying permeabilities. The findings demonstrate that the particle size decreased from 191 nm to 125 nm upon the addition of SiO2 nanoparticles to AOS surfactant, but increased to 389 nm upon the addition of SiO2 nanoparticles to HPAM. The dispersibility experiment showed that the SiO2 nanoparticle solution did not precipitate over 10 days. After adding 0.05% SiO2 nanoparticles to AOS surfactant, the zeta potential was −40.2 mV, while adding 0.05% SiO2 nanoparticles to 0.1% HPAM resulted in a decrease in the zeta potential to −25.03. The addition of SiO2 nanoparticles to AOS surfactant further reduced the IFT value to 0.19 mN/m, altering the rock wettability from oil-wet to strongly water-wet, with the contact angle decreasing from 110° to 18°. In low-permeability rock core oil displacement experiments, the use of AOS surfactants and HPAM for enhanced oil recovery increased the recovery rate by 24.5% over water flooding. The recovery rate increased by 21.6% over water flooding in low-permeability rock core experiments after SiO2 nanoparticles were added and surfactants and polymers were utilized for oil displacement. This is because the nanoparticles blocked small pore throats, resulting in increased resistance and hindered free fluid flow. The main causes of this plugging are mutual interference and mechanical entrapment, which cause the pressure differential to rise quickly. In high-permeability rock core oil displacement experiments, the use of AOS surfactants and HPAM for oil recovery increased the recovery rate by 34.6% over water flooding. Additionally, the recovery rate increased by 39.4% over water flooding with the addition of SiO2 nanoparticles and the use of AOS surfactants and HPAM for oil displacement. Because SiO2 nanoparticles create wedge-shaped structures inside highly permeable rock cores, they create structural separation pressure, which drives crude oil forward and aids in diffusion. This results in a comparatively small increase in pressure differential. Simultaneously, the nanoparticles change the rock surfaces’ wettability, which lowers the amount of crude oil that adsorbs and improves oil recovery.

PSIII-11 Effects of Inoculation of Alfalfa Hay with Pediococcus Pentosaceus and α-Amylase on Hay Temperature, Microbial Ecology, Nutrient Composition, and Feed Value

Abstract Haying in the Midwest is challenging, with excessive spring and early summer precipitation followed by unpredictable rain events throughout the growing months, forcing farmers to be innovative and resort to novel haying practices. High moisture haying with lactic acid bacterial (LAB) inoculants allows farmers to harvest earlier with less expenditure. This study examined how inoculating high-moisture alfalfa hay with Pediococcus pentosaceus and α-amylase (Magniva for Hay; Lallemand Animal Nutrition, Milwaukee, WI) affected hay temperature, microbial ecology, nutritional content, and feed value. Alfalfa was harvested at the late flowering stage and allowed to wilt in windrows for two days until the moisture level dropped to 20-25%, at which point half of the field was baled (20 bales) with the inoculant at 1.25 L ton-1, providing 1.0 × 106 cfu g-1 fresh forage of Pediococcus pentosaceus (NCIMB 12675) and 2.5 × 106 units of α-amylase (INOC). Uninoculated alfalfa baled at 15–18% moisture (20 bales) served as control (CON). The hay bales were stored under cover and sampled using a hay corer on days 0, 60, 120, and 180 to evaluate nutrient composition, microbial ecology, and feed value. Dallas Thermochron iButton sensors (Embedded Data Systems, Lawrenceburg, KY) were inserted into the center of hay bales during day 0 sampling (20 sensors per treatment) to measure the temperature every 4 h over 180 days. The core holes were air-tightened with alfalfa hay after installing the iButton sensors. SAS (SAS Institute Inc., 2012) mixed model technique was used to assess repeated measurements with treatment (T), day (D), and T × D effects. CON had greater LAB counts (log10 cfu g-1 DM) than INOC (7.45 vs. 7.11; P = 0.03) during storage. On days 0, 120, and 180 of storage, INOC had lower yeast counts (P &amp;lt; 0.02) than CON (T × D interaction). INOC exhibited higher core temperatures (P &amp;lt; 0.03) than CON on days 14, 21, and 28 of storage, peaking at 46.7°C on day 14. INOC reported lower DM than CON on days 60 and 120 of storage (P &amp;lt; 0.03). INOC had a higher CP concentration (18.0 vs. 16.9; P &amp;lt; 0.0001) than CON throughout storage. On days 60, 120, and 180 of storage, INOC had increased ADICP and NDICP (% DM) concentrations than CON (P &amp;lt; 0.05). Results indicated that inoculation of high moisture alfalfa hay with LAB inoculants is a viable alternative for farmers in the Midwest severely impacted by unpredictable weather events due to global warming. Further studies will provide detailed information on nutrient degradability and utilization for livestock production.

Exploring the impact of ions on oxygen K-edge X-ray absorption spectroscopy in NaCl solution using the GW-Bethe-Salpeter-equation approach.

X-ray absorption spectroscopy (XAS) is a powerful experimental tool to probe the local structure in materials with the core hole excitations. Here, the oxygen K-edge XAS spectra of the NaCl solution and pure water are computed by using a recently developed GW-Bethe-Salpeter equation approach, based on configurations modeled by path-integral molecular dynamics with the deep-learning technique. The neural network is trained on abinitio data obtained with strongly constrained and appropriately normed density functional theory. The observed changes in the XAS features of the NaCl solution, compared to those of pure water, are in good agreement between experimental and theoretical results. We provided detailed explanations for these spectral changes that occur when NaCl is solvated in pure water. Specifically, the presence of solvating ion pairs leads to localization of electron-hole excitons. Our theoretical XAS results support the theory that the effects of the solvating ions on the H-bond network are mainly confined within the first hydration shell of ions, however beyond the shell the arrangement of water molecules remains to be comparable to that observed in pure water.