The obesity epidemic has been on the rise due to changes in living standards and lifestyles. To combat this issue, sleeve gastrectomy (SG) has emerged as a prominent bariatric surgery technique, ...offering substantial weight reduction. Nevertheless, the mechanisms that underlie SG-related bodyweight loss are not fully understood.
In this study, we conducted a collection of preoperative and 3-month postoperative serum and fecal samples from patients who underwent laparoscopic SG at the First Affiliated Hospital of Shandong First Medical University (Jinan, China). Here, we took an unbiased approach of multi-omics to investigate the role of SG-altered gut microbiota in anti-obesity of these patients. Non-target metabolome sequencing was performed using the fecal and serum samples.
Our data show that SG markedly increased microbiota diversity and Rikenellaceae,
,
, Bactreoidales, and Enterobacteraies robustly increased. These compositional changes were positively correlated with lipid metabolites, including sphingolipids, glycerophospholipids, and unsaturated fatty acids. Increases of Rikenellaceae,
, and
were reversely correlated with body mass index (BMI).
In conclusion, our findings provide evidence that SG induces significant alterations in the abundances of Rikenellaceae,
,
, and Bacteroidales, as well as changes in lipid metabolism-related metabolites. Importantly, these changes were found to be closely linked to the alleviation of obesity. On the basis of these findings, we have identified a number of microbiotas that could be potential targets for treatment of obesity.
Non-aqueous or gaseous stimulants are alternative working fluids to water for hydraulic fracturing in shale reservoirs, which offer advantages including conserving water, avoiding clay swelling and ...decreasing formation damage. Hence, it is crucial to understand fluid-driven fracture propagation and morphology in shale formations. In this research, we conduct fracturing experiments on shale samples with water, liquid carbon dioxide, and supercritical carbon dioxide to explore the effect of fluid characteristics and in situ stress on fracture propagation and morphology. Moreover, a numerical model that couples rock property heterogeneity, micro-scale damage and fluid flow was built to compare with experimental observations. Our results indicate that the competing roles between fluid viscosity and in situ stress determine fluid-driven fracture propagation and morphology during the fracturing process. From the macroscopic aspect, fluid-driven fractures propagate to the direction of maximum horizontal stress direction. From the microscopic aspect, low viscosity fluid easily penetrates into pore throats and creates branches and secondary fractures, which may deflect the main fracture and eventually form the fracture networks. Our results provide a new understanding of fluid-driven fracture propagation, which is beneficial to fracturing fluid selection and fracturing strategy optimization for shale gas hydraulic fracturing operations.
The incidence rate of pancreatic neuroendocrine neoplasms （pNENs） has increased rapidly in recent years. However, the clinicopathological characteristics of pNENs are poorly understood. Medical ...records of patients who underwent surgery and were confirmed as pNENs by pathological examination from January 2003 to February 2015 in Qilu Hospital were reviewed retrospectively. A total of 100 patients, 36 males and 64 females, were included with a mean operation age of 46.26 ± 13.41 years. Among the 100 cases, 76 had insulinomas and 24 had non-functional pNENs. Tumor size ranged from 0.5 cm to 9 cm, and the mean size was 2.20 ± 1.40 cm. The percentages of TNM stages I, II, III, and IV tumors were 89.0%, 8.0%, 0.0%, and 3.0%, respectively. Based on the WHO classification, pNENs were classified into three grades： G1, G2, and G3. G1, G2, and G3 tumors were confirmed in 72.9%, 23.7%, and 3.4% patients, respectively. The positive rates of CgA and Syn immunohisto- chemical staining were 94.5% （69/73） and 100% （74/74）, respectively. Compared with insulinoma, non-functional pNENs have larger tumor sizes, more advanced TNM staging, a higher Ki-67 index, and a higher rate of liver metastasis （P 〈 0.05）. In conclusion, pNENs are heterogeneous tumors with varying clinical manifestations, diverse tumor biological characteristics, and different prognoses. Non-functional pNENs present a more aggressive behavioral model and have poorer prognosis than functional pNENs.
The greater adsorption ability of shale to CO2 offers an alternative method to enhance shale gas recovery, where a potential solution for CO2 sequestration into a deep shale reservoir can also be ...realized. Clay minerals are the important storage space for shale gas. In this work, the isotherm adsorption curves of CH4 and CO2 on montmorillonite at 288 K, 308 K and 328 K were obtained using gravimetric apparatus. The selectivity factor of CO2 over CH4 (SCO2/CH4) and Henry's constants (KH) of CH4 and CO2 were calculated. More importantly, the thermodynamics parameters of CH4 and CO2, including Gibbs free energy change (ΔG), surface potential (Ω), isosteric heat of adsorption (Qst) and entropy change (ΔS), were thoroughly analysed. The results indicate that all SCO2/CH4 values are obviously greater than one, and injecting CO2 into a clay-rich shale reservoir to enhance the shale gas recovery is feasible. CH4 has smaller KH than CO2, which shows that CH4 has a weaker affinity on the montmorillonite surface. Low temperature helps to enlarge KH and promote the adsorption of CH4 and CO2. Increasing the pressure causes the increase in ΔG and Ω of CH4 and CO2. The higher ΔG and Ω of CO2 compared to CH4 reveal that the CO2 adsorption on montmorillonite is more favourable and spontaneous. When the loading increases, the Qst values of CH4 and CO2 reduce. CH4 has a smaller Qst than CO2, which suggests the stronger interaction of CO2 with montmorillonite. CH4 and CO2 have decreasing ΔS with the loading. Under larger surface coverage conditions, the disorder of the adsorbed molecules is larger, and most of the injected molecules are trapped as a free state in the pore space. The higher ΔS of CO2 illustrates that CO2 molecules constitute a much more stable rearrangement than CH4 molecules. The temperature has a slight effect on the ΔS of CH4 and CO2.
•Montmorillonite has a stronger adsorption affinity for CO2 than CH4.•Displacing CH4 by CO2 on montmorillonite-bearing shale is feasible.•Adsorbed CO2 has more orderly arrangement than CH4 on montmorillonite.
Understanding the adsorption behaviors of CH4, N2, CO2, and their mixture in clay minerals is crucial to the approach of enhanced hydrocarbon recovery using gas injection with application in ...clay-rich gas-shale reservoirs. In this study, the adsorption measurements of CH4, N2, CO2, and their mixture on montmorillonite were conducted using a gravimetric technique. The underlying competitive adsorption mechanism of CH4, N2, and CO2 on montmorillonite was discussed using Henry's constant, adsorption selectivity, and thermodynamic variables. The adsorption selectivity of CO2 over N2 (αCO2/N2) was the highest, followed by the selectivity of CO2 over CH4 (αCO2/CH4) and that of CH4 over N2 (αCH4/N2). The αCO2/CH4 value was greater than one, confirming that CO2 can stimulate CH4 desorption through molecular swapping. Reducing the temperature increased the selectivity and the desorption of the pre-adsorbed gas was more easily triggered by the injection of the favorably adsorbing gas at lower temperatures. The uptake and affinity of CO2 were the highest, whereas N2 exhibited the smallest uptake and affinity. In addition, CO2 adsorption was more spontaneous than CH4 and N2 adsorption. Although N2 adsorption was less favorable than CH4 adsorption, injecting N2 could lower the spontaneity of CH4 adsorption by decreasing the CH4 partial pressure. The adsorbed CO2 molecules were the most ordered, and the freedom of adsorbed N2 molecules was the highest. The adsorption isotherm of the mixed gases was closer to that of the strong adsorption component. Thus, a strong adsorption gas plays a leading role in the adsorption of mixed gases.
•The order of affinities of gases on montmorillonite is as follows: CO2 > CH4 > N2.•Adsorbed CO2 molecules are more orderly than adsorbed CH4 and N2 molecules.•Strong adsorption gas plays a dominant role in adsorption process of mixed gases.
Based on the coupling algorithm of smoothed particle hydrodynamics and finite element method, numerical simulation of high-velocity water jet impacting heterogeneous concrete containing aggregates ...according to the real concrete CT slices was conducted to study the damage evolutions and fracture characteristics of concrete with real structure. The damage evolution and fragmentation process of heterogeneous concrete were obtained, and the fracture characteristic was compared with homogeneous concrete. The internal energy change laws and the damage and stress evolutions in homogeneous and heterogeneous concretes at different time were investigated. And the failure mechanisms of water jet crushing heterogeneous concrete were revealed. The results show that the concrete elements mainly suffer multi-stage plastic damage accumulation failure induced by water jet impact due to stress wave effect, pressured water wedge effect, water flow scouring effect, squeezing effect of aggregate, and stress concentrations. The failures of upper and deep concrete elements are mainly caused by compressive shear stress, which is combined with tensile stress. In homogeneous concrete, the bowl-shaped broken pit with smooth sidewall and the symmetrically distributed cracks are formed. In heterogeneous concrete, the aggregate will prolong the damage accumulation process and lead to the formation of the abnormal broken pit with irregular and rough contour. Cracks prefer to propagate at interface between aggregate and mortar, and concrete elements at interfaces will suffer the sudden brittle failure caused by stress concentration when the damage accumulates to a certain extent. Overall, the internal energy in concrete first rapidly and then slowly increases, and there is a poorer absorption efficiency of jet kinetic energy for heterogeneous concrete, in which the internal energy of aggregates and mortar is closely related to the specific impact object of water jet. The research results would lay the theoretical foundation for water jet efficiently crushing concrete.
Display omitted
•Water jet impacting concrete with actual aggregates was simulated and verified.•Damage evolution and fragmentation process were investigated.•Energy changes and damage-stress evolutions were compared.•Failure mechanisms of heterogeneous concrete were revealed.
Research on the physicochemical reactions between supercritical carbon dioxide (Sc-CO2) and shale at different temperature is essential for geological CO2 sequestration. In this paper, shale from the ...Longmaxi formation in Sichuan basin of China was collected to study the changes in mineral composition, pore structure, and organic functional groups treated with Sc-CO2 at fixed pressure 8 MPa and temperatures 40 °C to 80 °C. Samples were analyzed with x-ray diffraction, CO2/N2 gas adsorption, and Fourier transform infrared spectroscopy. The results show that the dissolution of clay minerals by Sc-CO2 first declined, but then increased when the temperature increased; dissolution reached a minimum at 60 °C. The specific surface area, total pore volume, predominant pore type (mesopores), and fractal dimension of the shale pore structure first increases and then decreases with increasing temperature. The destruction of hydroxyl structures by Sc-CO2 is related to the destruction of OH–N and ring hydroxyls. As the temperature increases, the hydroxyl destruction first increases and then decreases. The aromatic hydrocarbons are mainly dominated by 3H and 2H, and their abundances increase significantly as temperature increases, whereas the 4H shows a decreasing trend; the 1H abundance does not change appreciably. The relative abundances of aromatic and aliphatic hydrocarbons decrease linearly as the temperature increases. These research results provide theoretical support for the geological storage of Sc-CO2 in shale at different temperatures.
Display omitted
•Lots of experiments on water jets impinging rocks with different structures were conducted.•Breakage patterns, failure mechanisms, erosion depth and area, and cracks distribution of ...the eroded rocks with different structures were obtained.•Damage field distribution in eroded rocks were characterized quantitatively.
This paper aims to investigate the damage and fracture characteristics of rocks with different structures under water jet impact. Three types rocks including heterogeneous coal, homogeneous sandstone, and transversely isotropic shale, were selected as the impact target rock. Water-jet impingement experiments with jet velocities varying from 447 m/s to 774 m/s were conducted. The rock macro-breakage characteristics were obtained by describing the breakage patterns, measuring the erosion depth and area, and counting the cracks number. A 3D reconstruction method based on the computed tomography and digital image processing technology was proposed to visualize the internal breakage characteristics and quantitatively analyze the damage field distribution. Combined with fracture morphology from scanning electron microscope, the failure mechanisms of rocks with three structures under water jet impact were revealed. The results indicate that coal, sandstone and shale will experience different breakage patterns with the increasing jet velocity: layered transverse cracks → “十”-type crack network → splitting crack, only one spindle-shape erosion pit, surface debris spalling → layered transverse cracks → “T”-type crack network. The effects of jet velocity and rock structure on the evaluation indexes (such as erosion depth and damage area, the number and angle of transverse cracks) were investigated thoroughly. In addition, the relationships between total damage degree based on breakage volume and jet velocity, and between damage variable based on breakage area and erosion depth, were compared and discussed. The failure mechanisms of three rocks impacted by water jets are as follows: (i) the reflection and interference of stress wave combined with the pressured water wedge effect cause the layered breakage and longitudinal splitting breakage of heterogeneous coal; (ii) the grinding effect of back flow mainly accounts for the formation of spindle-shape erosion pit in homogeneous sandstone; (iii) the shock stress wave effect and bedding structure lead to the spalling of large shale block and layered breakage, and the reflected wave tensile accompanied with pressured water wedge effect cause the tensile splitting breakage.
In this paper, the adsorption behaviors of water vapor in non-swelling clays (chlorite and kaolinite) and swelling clay (montmorillonite) were researched, and the thermodynamics characteristics about ...the adsorption for water vapor in three clays were systematically analyzed. The results display that montmorillonite has the highest adsorption affinity and adsorption ability for water vapor, while the adsorption affinity and uptake for water vapor on chlorite are the lowest. In montmorillonite, the uptake for secondary adsorption is smaller than the primary adsorption uptake during the entire pressure range. In chlorite and kaolinite, the secondary adsorption center possesses a smaller adsorption capacity at low vapor pressure condition, and the primary adsorption quantity is lower in the high vapor pressure region. With improving pressure, the water vapor adsorption spontaneity in chlorite and kaolinite first increases and then decreases. Contrarily, the spontaneity degree for adsorption of water vapor in montmorillonite can be constantly improved by enhancing the vapor pressure. The values for entropy loss and isosteric heat of adsorption in the three clays for water vapor are as follows: montmorillonite > kaolinite > chlorite. Compared with chlorite and kaolinite, the montmorillonite surface possesses the strongest interaction with water molecules, and the water molecules adsorbed in montmorillonite are the most stable. The trapping of water molecules within shale sediments is mainly resulting from swelling clay. Attention should be paid to mineral composition and content before the hydraulic fracturing process.
PDF
