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Intraoperative blood loss is a significant concern in patients with metastatic spinal disease. Early identification of patients at high risk of experiencing massive intraoperative blood loss is crucial as it allows for the development of appropriate surgical plans and facilitates timely interventions. However, accurate prediction of intraoperative blood loss remains limited based on prior studies. The purpose of this study was to develop and validate a web-based artificial intelligence (AI) model to predict massive intraoperative blood loss during surgery for metastatic spinal disease. An observational cohort study. Two hundred seventy-six patients with metastatic spinal tumors undergoing decompressive surgery from two hospitals were included for analysis. Of these, 200 patients were assigned to the derivation cohort for model development and internal validation, while the remaining 76 were allocated to the external validation cohort. The primary outcome was massive intraoperative blood loss defined as an estimated blood loss of 2,500 cc or more. Data on patients' demographics, tumor conditions, oncological therapies, surgical strategies, and laboratory examinations were collected in the derivation cohort. SMOTETomek resampling (which is a combination of Synthetic Minority Oversampling Technique and Tomek Links Undersampling) was performed to balance the classes of the dataset and obtain an expanded dataset. The patients were randomly divided into two groups in a proportion of 7:3, with the most used for model development and the remaining for internal validation. External validation was performed in another cohort of 76 patients with metastatic spinal tumors undergoing decompressive surgery from a teaching hospital. The logistic regression (LR) model, and five machine learning models, including K-Nearest Neighbor (KNN), Decision Tree (DT), XGBoosting Machine (XGBM), Random Forest (RF), and Support Vector Machine (SVM), were used to develop prediction models. Model prediction performance was evaluated using area under the curve (AUC), recall, specificity, F1 score, Brier score, and log loss. A scoring system incorporating 10 evaluation metrics was developed to comprehensively evaluate the prediction performance. The incidence of massive intraoperative blood loss was 23.50% (47/200). The model features were comprised of five clinical variables, including tumor type, smoking status, Eastern Cooperative Oncology Group (ECOG) score, surgical process, and preoperative platelet level. The XGBM model performed the best in AUC (0.857 [95% CI: 0.827, 0.877]), accuracy (0.771), recall (0.854), F1 score (0.787), Brier score (0.150), and log loss (0.461), and the RF model ranked second in AUC (0.826 [95% CI: 0.793, 0.861]) and precise (0.705), whereas the AUC of the LR model was only 0.710 (95% CI: 0.665, 0.771), the accuracy was 0.627, the recall was 0.610, and the F1 score was 0.617. According to the scoring system, the XGBM model obtained the highest total score of 55, which signifies the best predictive performance among the evaluated models. External validation showed that the AUC of the XGBM model was also up to 0.809 (95% CI: 0.778, 0.860) and the accuracy was 0.733. The XGBM model, was further deployed online, and can be freely accessed at https://starxueshu-massivebloodloss-main-iudy71.streamlit.app/. The XGBM model may be a useful AI tool to assess the risk of intraoperative blood loss in patients with metastatic spinal disease undergoing decompressive surgery. [ABSTRACT FROM AUTHOR]

Background: Blood loss in posterior surgery patients with thoracolumbar metastasis posed a significant challenge to surgeons. This study aimed to explore the risk factors of blood loss in posterior surgery for patients with thoracolumbar metastasis.Methods: One hundred forty-two patients were retrospectively reviewed. Their baseline characteristics were recorded. The Gross equation was used to calculate blood loss on a surgical day. Multivariate linear regression was used to analyze the risk factors.Results: Mean blood loss of 142 patients were 2055 ± 94 ml. Hypervascular primary tumor (kidney, thyroid and liver) (P = 0.017), wide or marginal excision (en-bloc: P = 0.001), metastasis at the lumbar spine (P = 0.033), and the presence of extraosseous tumor mass (P = 0.012) were independent risk factors of blood loss in the posterior surgery. Sub-analysis showed that wide or marginal excision (en-bloc: P < 0.001) and metastasis at lumbar spine (P = 0.007) were associated with blood loss for patients with non-hyper vascular primary tumors. Wide or marginal excision (piece-meal: P = 0.014) and the presence of an extraosseous tumor mass (P = 0.034) were associated with blood loss for patients with hypervascular primary tumors.Conclusion: Hypervascular primary tumor (kidney, thyroid, and liver) was an independent risk factor of blood loss in the posterior surgery. The presence of extraosseous tumor mass and wide or marginal excision (piece-meal) were independent risk factors for patients with hypervascular primary tumors. Metastasis at the lumbar spine and wide or marginal excision (en-bloc) were independent risk factors for patients with non-hyper vascular primary tumors. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the effect of timing of surgery on neurological recovery for patients with metastatic spinal cord compression (MSCC).Methods: According to the timing of surgery, 75 patients with incomplete paraplegia caused by MSCC were assigned to 3 groups: within 3 days (group A), between 4 days and 7 days (group B), and after 7 days (group C). T-test, one-way ANOVA, Mann-Whitney U-test, and Chi-square test were used to evaluate the difference in the improvement of American Spinal Injury Association Impairment Scale (AIS) and ambulatory status, the incidence of perioperative complications, surgical site infection, and the length of hospital stay between 3 groups.Results: Patients with incomplete paraplegia treated in our department had an average of 17.4±1.8 days delayed and most occurred before hospitalization (4.0±0.4 vs 13.2±1.8, P<0.001). There was no significant difference in the AIS improvement between patients with different pre-op AIS. The timing of surgery was significantly correlated with AIS improvement (correlation coefficient=-0.257, P=0.019). Sub-analysis showed that patients who underwent surgery within 7 days (group A and group B) had significantly better AIS improvement compared with group C (improved at least 1 grade, P=0.043; improved more than 1 grade, P=0.039) and the surgery timing was more important for patients with AIS B and C. The timing of surgery was significantly correlated with the length of hospital stay (correlation coefficient=0.335, P=0.003). Patients of group C had the longest length of hospital stay (P=0.002). The incidence of perioperative complications and surgical site infection did not differ significantly between the 3 groups.Conclusion: Delay surgery was common in incomplete paraplegia patients with MSCC. Patients with AIS B and C who underwent surgery within 7 days had better AIS improvement. [ABSTRACT FROM AUTHOR]

Background: Cement leakage into venous blood posed significant challenge to surgeons. The aim of the study was to create a Peking University First Hospital Score (PUFHS) which could evaluate the probability of vascular cement leakage among spine metastases patients following percutaneous vertebroplasty.Methods: The study retrospectively enrolled 272 spine metastases patients treated with percutaneous vertebroplasty. We randomly extracted all enrolled patients as the training or validation group and baseline characteristic comparison was assessed between the two groups. Creation of the PUFHS was performed in the training group and validation of the PUFHS was performed in the validation group.Results: Of all the 272 patients, the total number of included vertebrae was 632 and the median treated levels were 2 per patient. Vascular cement leakage occurred in 26.47% (72/272) of patients. The baseline characteristics were comparable between the two groups (P > 0.05). Three risk predictors (primary cancer types, number of treated vertebrae levels, and vertebrae collapse) were included in the PUFHS. The area under the receiver operating characteristic curve (AUROC) of the PUFHS was 0.71 in the training group and 0.69 in the validation group. The corresponding correct classification rates were 73.0 and 70.1%, respectively. The calibration slope was 0.78 (95% confidence interval[CI]: 0.45-1.10) in the training group and 1.10 (95% CI: 0.73-1.46) in the validation group. The corresponding intercepts were 0.06 (95% CI: - 0.04-0.17) and - 0.0079 (95% CI: - 0.11-0.092), respectively.Conclusions: Vascular cement leakage is common among spine metastases after percutaneous vertebroplasty. The PUFHS can calculate the probability of vascular cement leakage, which can be a useful tool to inform surgeons about vascular cement leakage risk in advance. [ABSTRACT FROM AUTHOR]

An oilfield has been developed with waterflooding for a long time, and the water cut has reached a high level. Surfactant-polymer (SP) flooding is considered as the following enhanced oil recovery (EOR) technique. To determine the feasibility of SP flooding in this oilfield, the microscopic oil displacement experiments are performed, and the distribution of remaining oil after waterflooding and SP flooding is observed. The recovery rates are measured by the producing liquid amount and nuclear magnetic resonance (NMR) technique. The two methods show similar measurement results, with deviations of about 10%. The contributions of different pore and throat diameters are analyzed with the NMR technique. The results show that SP flooding has a much lower contribution limit of pore and throat diameter than waterflooding, indicating that SP flooding can effectively improve sweep efficiency. The SP flooding can improve by about 30% EOR rate. The frozen slicing technique and ultraviolet fluorescence excitation are applied to observe the status and distribution of remaining oil. The results show that both waterflooding and SP flooding can effectively reduce all types of remaining oil. Comparing the remaining oil proportions in the high and low permeability cores, we can conclude that the high permeability contributes to the performance of waterflooding and SP flooding. This work proves the efficiency of SP flooding in this oilfield development and provides a microscopic explanation of remaining oil distribution after waterflooding and SP flooding. • SP flooding is an effective approach for EOR compared with waterflooding. • Both waterflooding and SP flooding can effectively reduce all types of remaining oil. • High permeability contributes to the performance of waterflooding and SP flooding. • Recovery after waterflooding and SP flooding can reach 43.58% and 8.21% respectively. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the migration and blocking mechanism of self-aggregated divinylbenzene-co-acrylamide (DCA) microspheres as a novel profile control. Scanning electron microscopy (SEM) and laser diffracting measurement experiments were conducted to examine the shape and size of the microspheres. The optimal matching factor between microsphere diameter and the pore throat was from 0.15 to 0.19. The migration position of DCA microspheres in porous media was studied via SEM. The images revealed that DCA microspheres can exhibit long-distance migration. Moreover, the effects of different matching factors on oil recovery rate have been investigated by the core displacement experiments. The enhanced oil recovery was the highest when the DCA microspheres with the optimum matching factor was injected. Additionally, the oil saturation distribution demonstrates that DCA microspheres with optimal matching factors can enhance sweep efficiency by plugging high-permeability water channels. Image 1 • Self-aggregating microspheres with particle sizes ranging from 50 nm to 102 μm were synthesized. • Self-aggregating microspheres have shell-core structures and can be aggregated by high-valence metal ions. • The optimum matching factor of self-aggregating microspheres is from 0.15 to 0.19. • Self-aggregating microspheres gathered in the pore throat and formed a partial seal inside the core. • Self-aggregating microspheres can block the high-permeability zones and increased sweep efficiency. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the perioperative safety and efficacy of the Mini-open and trans-tubular approach in patients with spinal metastases who underwent decompression surgery. Methods: 37 consecutive patients with spinal metastases who underwent decompression surgery through a Mini-open or trans-tubular approach were retrospectively reviewed between June 2017 and June 2022. Thirty-four patients were included in this study. 19 underwent decompression surgery through the Mini-open approach, and 15 underwent the Trans-tubular approach. T-test and chi-square test were used to evaluate the difference between baseline data and primary and secondary outcomes. Results: Baseline characteristics did not differ significantly between Trans-tubular and Mini-open groups except for the Ambulatory status (P < 0.001). There was no significant difference in blood loss between the two groups (P = 0.061). Operative time, intraoperative blood transfusion, intraoperative complication (dural tear), and postoperative hospitalization were comparable in the two groups (P > 0.05). The trans-tubular group had significantly less amount of postoperative drainage (133.5 ± 30.9 ml vs. 364.5 ± 64.2 ml, p = 0.003), and the time of drainage (3.1 ± 0.2 days vs. 4.6 ± 0.5 days, p = 0.019) compared with Mini-open group (P < 0.05). Sub-group analysis showed that for patients with hypo-vascular tumors, the Trans-tubular group had significantly less blood loss than the Mini-open group (951.1 ± 171.7 ml vs. 1599.1 ± 105.7 ml, P = 0.026). Conclusions: Decompression through Mini-open or Trans-tubular was safe and effective for patients with spinal metastases. The trans-tubular approach might be more suitable for patients with hypo-vascular tumors. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of C-reactive protein (CRP) on the prognosis of adult patients with Immune thrombocytopenia purpura (ITP). A retrospective study of 628 adult ITP patients, as well as 100 healthy and 100 infected patients, attending the Affiliated Hospital of Xuzhou Medical University from January 2017 to June 2022 was performed. The ITP patients were grouped according to their CRP levels, and the differences in clinical characteristics of each group and the influencing factors of efficacy in newly diagnosed ITP patients were analyzed. CRP levels were significantly higher in the ITP and infected groups compared with healthy controls (P < 0.001), and platelet counts were significantly lower in the ITP group (P < 0.001). Between the CRP normal and elevated group, their age, white blood cell count, neutrophil count, lymphocyte count, red blood cell count, hemoglobin, platelet count, complement C3 and C4, PAIgG, bleeding score, proportion of severe ITP, and proportion of refractory ITP were significantly different (P < 0.05). Patients of severe ITP (P < 0.001), refractory ITP (P = 0.002), and with active bleeding (P < 0.001) had significantly higher CRP levels. Patients with no response after treatment had significantly higher CRP levels than those who achieved CR or R (P < 0.001). Platelet counts (r = − 0.261, P < 0.001) in newly diagnosed ITP patients and treatment outcomes (r = − 0.221, P < 0.001) were negatively correlated with CRP levels, and bleeding score was positively correlated with CRP levels (r = 0.207, P < 0.001). Treatment outcome was positively correlated with decrease in CRP levels (r = 0.313, P = 0.027). A multifactorial regression analysis of the influencing factors of treatment outcomes on newly diagnosed patients found that CRP was an independent risk factor of the prognosis (P = 0.011). In conclusion, CRP can help assess the severity and predict the prognosis of ITP patients. [ABSTRACT FROM AUTHOR]

To explore the prognostic value of red blood cell distribution width (RDW) in newly diagnosed aplastic anemia (AA) patients treated with cyclosporine A (CsA) plus androgen or CsA alone. We retrospectively analyzed the clinical outcome of 220 patients with AA. According to the baseline level of RDW before treatment, the patients were divided into the high-RDW group (RDW ≥ 15%) and the normal-RDW group (RDW < 15%). The median RDW of non-severe AA (NSAA) and severe AA (SAA) patients was 15.65% and 15.35%, respectively; this were significantly higher than that of very severe AA (VSAA) patients (13.35%). With median follow-up being 46 months, AA patients in the high-RDW group showed better 5-year OS and PFS than the normal-RDW group (93%: 75.3%; 74.3%: 61%). There was a higher ORR in the high-RDW group than the normal-RDW group (68.7%: 52.3%). The ORR of NSAA patients in the high-RDW group was better than that in the normal RDW group (75.8%: 60%). The 5-year OS of SAA/VSAA patients in the high-RDW group was significantly higher than the normal-RDW group (81.8%: 50.8%). This is the first documentation on the prognostic value of RDW in AA patients receiving CsA treatment with long-term follow-up, which had shown that high RDW at diagnosis was a better prognostic factor. [ABSTRACT FROM AUTHOR]

Abstract Pseudo threshold pressure gradient (PTPG) is a significant parameter that characterizes fluid flow in low permeability and tight reservoirs, which would illustrate pressure derivative curves anomaly caused by low-velocity non-Darcy flow. During the development of low-permeability and tight reservoirs, PTPG is a dynamic parameter influenced by effective stress. A series of core flooding experiments have been conducted in this paper to conclude the relationship between effective stress and PTPG with the unique experimental method. In the experiment, the precision of pressure measurement is greatly improved by a novel device and the influence of the core-end effect and the defects of the core holder on the experimental results is eliminated. The results show that PTPG increase along with the increase of effective stress. Based on the conclusion, a dynamic PTPG model is established, and the corresponding parameters are derived by fitting the experimental data. The well performance of a vertical well estimated by this model shows the production rate and recovery factor of non-Darcy flow considering dynamic PTPG are smaller than that of Darcy flow but larger than that of conventional non-Darcy flow. The recovery factor of non-Darcy flow considering dynamic PTPG is 21.2% higher than that of conventional non-Darcy flow when the production time is 800 days. The production rate and recovery factor curves of different overburden pressure show that the higher the overburden pressure is, the worse the productivity of the well is. The recovery factor at an overburden pressure of 50 MPa is 11.1% lower than that at an overburden pressure of 30 MPa. Highlights • Novel experimental device and method are designed to measure the pseudo threshold pressure gradient (PTPG). • Accurate mathematical relationship between effective pressure and PTPG is proposed. • A model with dynamic PTPG is established and used to study the vertical well production performance. • The recovery factor of non-Darcy flow considering dynamic PTPG is larger than that of conventional non-Darcy flow. • The well productivity in low-permeability and tight reservoirs decrease with the increase of overburden pressure. [ABSTRACT FROM AUTHOR]

Coffee is one of the most valuable agricultural commodities worldwide, second only to oil in terms of international trade. Coffea arabica L. is a widely cultivated and economically important crop that is responsible for about 90% of the global production of coffee. In this study, we selected five C. arabica cultivation sites at different altitudes to clarify the effects of altitude on rhizospheric soil physical–chemical characteristics and microbial communities. The samples collected at low altitudes were more nutrient-deficient and acidic than the soil samples collected at medium–high altitudes. The Proteobacteria-to-Acidobacteria ratio increased from lower altitudes to medium–high altitudes. Additionally, although Ascomycota was the dominant fungal phylum, it was unaffected by the altitude. Furthermore, the alpha richness and diversity of the bacterial and fungal communities were higher at medium–high altitudes than at low altitudes. Moreover, the redundancy analysis indicated that microbial phyla were closely associated with pH. These findings suggest that C. arabica should be cultivated at medium–high altitudes, which is conducive to sustainable management and the production of high-quality C. arabica beans. [ABSTRACT FROM AUTHOR]

Amomum villosum, which is an important perennial medicinal plant, easily suffers from continuous cropping obstacles in the plantation. The aim of this study is to find an effective method to solve the problem of A. villosum continuous cropping. In this study, we analyzed four fields in which A. villosum was continuously cropped and a fallow field to reveal the effects of continuous cropping on the rhizosphere soil physicochemical properties, enzyme activities, and bacterial and fungal communities. Most of the soil nutrient contents gradually increased as the number of years of continuous cropping increased, whereas the soil pH decreased slightly. The soil urease and acid phosphatase activities tended to increase as the length of the continuous cropping period increased, which may have accelerated the conversion of soil substances. Furthermore, the alpha diversity of the bacterial and fungal communities decreased as the duration of the continuous cropping period increased. Additionally, the redundancy analysis revealed that bacterial and fungal community structures at the phylum level were the most correlated with pH value and catalase activity, respectively. This study may be useful for promoting the continuous cropping and sustainable development of A. villosum. [ABSTRACT FROM AUTHOR]

A great deal of oil field is currently produced using water flooding and the water cut has reached a high level, which requires enhanced oil recovery (EOR) techniques to improve the recovery. Surfactant-polymer (SP) flooding is the combination of surfactant flooding and polymer flooding. The polymer is added to increase the viscosity and viscoelasticity of the fluid while the surfactant is included to decrease the oil–water interfacial tension and change the wettability. Although the mechanism of SP flooding has been deeply investigated, the application of SP flooding on a specific oil field requires the selection of optimal SP system. Therefore, for the first time, we performed a series of experiments to determine the optimal SP system for high water-cut oil field. In the injection capability experiment, we observe that the SP system is injected into the core with less resistance compared with single polymer solution. In the flooding experiment, regardless of the polymer types, the improvement of recovery becomes significant when the injected PVs increases. SP flooding shows the higher improvement of recovery compared with single polymer flooding or surfactant flooding. Based on the performance of recovery improvement, we recommend the optimal SP system for the studied case is the combination of DQ-TSRP01 polymer and surfactant. The optimal injection parameters of this SP system are 1500 mg/L polymer concentration, 0.3 injection PV and the injection timing of 96% water cut. The finding of this study can help for better understanding of the application of SP flooding in high water-cut oil field production. • SP system (DQ-TSRP01 + surfactant) significantly improves the oil recovery. • Optimal injection parameters are 1500 mg/L polymer concentration, 0.3 injection PV. • Existence of surfactant in the SP system reduces the residual resistance coefficient. • Improvement of recovery becomes significant when the injected PVs increases. [ABSTRACT FROM AUTHOR]

Recently, as the demand for fossil and renewable energy continuously increases, enhancing oil recovery has become one of the key methods to meet the increased requirement. However, most of the oilfields are facing serious problems, including formation heterogeneity and low recovery factor. Therefore, further analysis is required to study the distribution of remaining oil and how to enhance oil recovery effectively. In this study, the core samples of different reservoir types were employed and characteristics of pore structure were measured by a high‐pressure mercury porosimeter. The recovery factor and distribution of remaining oil with different reservoir types were determined by core flooding experiments and nuclear magnetic resonance tests. According to the results, the heterogeneity of pore structure becomes weaker as the permeability of the reservoir increases. The recovery during different periods improved as the core permeability increased. The distribution of remaining oil in different pore sizes has an obvious difference. The contribution of the recovery factor is highest in smallpores and mesopores for type II reservoir while is greatest in mesopores and macropores for type III reservoir. These results can provide theoretical and technical support for further enhancing oil recovery. [ABSTRACT FROM AUTHOR]

Background: The study aimed to identify the risk factors of cement leakage following percutaneous vertebroplasty for spinal metastases.Methods: 230 consecutive patients with 530 vertebrae were retrospectively reviewed. Characteristics including age, primary cancer, location, pathological fracture, the integrity of the posterior wall, and the volume of bone cement were considered as potential risk factors. Cement leakage was evaluated by postoperative imaging examination and classified into three subtypes with different potential sequelae: spinal canal leakage, intravascular leakage around vertebrae, intradiscal and paravertebral leakage. Univariate and multivariate analyses were used to assess the risk factors.Results: Leakage was detected in 185 vertebrae (34.9%), 18.3% for intradiscal and paravertebral, 13.2% for intravascular around vertebrae, and 7.0% for spinal canal. Multivariate analysis showed that incomplete posterior wall (P = 0.001) and breast cancer (P = 0.015) were strong predictive factors for spinal canal leakage, incomplete posterior wall (P = 0.024) was for intravascular leakage around vertebrae, thoracic (P = 0.010) and pathological fracture (P = 0.000) were for intradiscal and paravertebral leakage.Conclusions: Our findings suggest that cement leakage is common following percutaneous vertebroplasty for spinal metastases. The incomplete posterior wall is an unfavourable factor for intravascular leakage around vertebrae. Vertebrae with incomplete posterior wall and breast cancer metastases are more likely to develop spinal canal leakage. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to develop an algorithm to predict cement injection volumes in patients with spine metastases treated with percutaneous vertebroplasty (PVP). Risk factors were also analyzed for intra-spinal canal cement leakages.Patients and Methods: A retrospective analysis of 584 vertebrae in 251 patients. Patients and vertebrae were divided into three groups based on grades of tumor invasion to the spinal cord. Patients with the complete posterior wall of vertebrae were classified into group A, patients without the complete posterior wall of vertebrae but with normal Dural sac were classified into group B, and patients with deformation of the Dural sac but without neurological symptom were classified into group C. We systematically reviewed demographic data, clinical parameters, radiology features, and cement leakages among the three groups. The multiple linear regressions were used to screen potential risk factors and develop the algorithm to predict injected cement volumes in vertebrae. Significant factors were included in the algorithm. Potential risk factors for intra-spinal canal cement leakage were analyzed using the multiple logistic regressions.Results: In the study, 17.1% (100/584) of vertebrae occurred cement leakages. Vertebrae in group C (28.6%, 8/28) had the highest cement leakage rate than patients in group A (14.4%, 61/424) and B (23.5%, 31/132) (P=0.014). Vertebrae in group C (14.3%, 4/28) were also more prone to intra-spinal canal leakages (P=0.003). The multiple logistic analysis showed that the Bilsky scale was significantly associated with intra-spinal canal cement leakages (P<0.001). The multiple linear regression analysis showed that intercept (P<0.001), treated vertebrae level (P<0.001), cortical osteolytic destruction in posterior wall (P<0.001), and Bilsky scale (P=0.014) were significant and those variables were included in the algorithm. The algorithm was Y=3.1627－0.8677×treated vertebrae level－0.6182×cortical osteolytic destruction in the posterior wall－0.2819×Bilsky scale.Conclusion: An algorithm is proposed and can be used to calculate cement injection volumes in spine metastases treated with PVP. This algorithm can facilitate surgical planning and guide cement injections. Bilsky scale is an independent risk factor for intra-spinal canal cement leakages. We do not recommend PVP treated in patients with a Bilsky scale of 2 and 3 mainly due to a high rate of intra-spinal canal cement leakages. [ABSTRACT FROM AUTHOR]

This study explores oil recovery mechanisms of static imbibition in a tight sandstone under different imbibition pressures, simultaneously optimizing imbibition agents. To this end, the static imbibition experiments of two common agents, polyacrylamide (PAM) slick water and anion–nonionic surfactants, are conducted under atmospheric and reservoir pressure (20 MPa). The interfacial tension and contact angle of these two imbibition fluids are also measured. Herein, the entire recovery period and imbibition equilibrium time vs. pressure are determined. Based on NMR and high-pressure mercury injection measurements, the contributions of pores with different sizes to the displacement recovery during imbibition are quantified. Under atmospheric pressure, the recovery rate with the surfactant was measured higher than that of the PAM slick water. The main reason was that the former has a lower interfacial tension (0.0961 mN/m), stronger hydrophilicity (average contact angle 27.7°), and stronger oil-displacing effect. Under a reservoir pressure of 20 MPa, the surfactant had lower recovery rate than the PAM slick water, while the latter enhanced the recovery further. Under atmospheric pressure, both agents recovered the crude oil in the medium-sized and larger pores whereas, under reservoir pressure (20 MPa), they mainly recovered oil from the smaller and medium-sized pores. At higher imbibition pressures, both agents recovered more oil from the smaller and medium-sized pores, and less from micropores and larger pores. This indicated that higher pressures can further improve the driving force of fluid replacement, to improve oil production from finer and medium-sized pores significantly. Under atmospheric pressure, both agents reached imbibition equilibrium in approximately 20 days while this period was reduced for the surfactant and slick water to 16 and 12 days, respectively. Based on the results PAM slick water is recommended for EOR purposes in tight sandstone which can be generalized to similar formations around the globe. • Oil recovery experiments in tight sandstone to find the best imbibition agent are performed. • PAM slick water is recommended while pressure improves production from small and medium-sized pores. • Both utilized agents reach equilibrium in 20 days in P(atm) while reservoir pressure reduces the time for the slick water. [ABSTRACT FROM AUTHOR]

Background. This retrospective review evaluated the clinical features and surgical outcomes of parosteal osteosarcoma (POS). Methods. Nine patients were surgically treated and followed up. Their mean age was 30.8 years. Clinical information and oncologic outcomes of each case were analyzed. Results. Sites of involvement were all in the femur, and all tumors arose from the metaphyseal area of the distal femur. Biopsies for definite diagnoses were performed in just two of the nine cases. Wide resection was applied for all tumors. Surgical evaluations were a 1-cm-wide procedure in six cases and a 2-cm-wide procedure (or more) in three cases. All patients were found to be continuously disease free during the follow-up period of 115.1 months. Conclusion. POS showed characteristic findings on radiographic images. Therefore, wide resection without biopsy could be performed in 77.8% (7/9) of the cases. This procedure may contribute to attaining better limb function, because of preventing contamination of healthy surrounding tissue and minimizing the extent of resection. The safety margin was evaluated as a 1-cm-wide procedure. For the choice of reconstruction, indication of autobone grafting (3/9) or total knee replacement (TKR) (6/9) depended on tumor size, location, and shape. With no adjuvant treatments, all cases have shown good clinical courses during the entire follow-up period of about 10 years. [ABSTRACT FROM AUTHOR]