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Objective To explore the possible molecular regulation mechanism of COPB2 on human osteosarcoma cells based on the bioinformatics analysis of ingenuity pathway analysis (IPA). Methods RT-qPCR was used to detect the expression levels of COPB2 in human osteosarcoma cell lines U-2OS, MG-63, HOS and Saos-2. U-2OS was used as the research object and divided into silence group (KD) and control group (NC). U-2OS cells were infected by green fluorescent protein-labeled lentivirus and the KD group contained COPB2 silenced sequence. Human gene expression profiling microarray was used to detect the difference in gene expression profile of U-2OS cells after COPB2 silencing. The detection information was input into the IPA software for bioinformatics analysis, including classical pathway analysis, upstream regulation analysis, disease function analysis, regulatory effect analysis and interaction network analysis. Results COPB2 had a high expressive abundance in four human osteosarcoma cell lines. There were significant differences in the expression of 1393 genes between KD group and NC group; 831 genes were up-regulated and 562 genes were down-regulated. After COPB2 knockdown, the inhibition of angiogenesis by TSP1 pathway and acute phase response pathway were significantly activated, while cyclins and cell cycle regulation pathway were significantly inhibited. COPB2 mainly affected neoplasia, invasion and anoikis of osteosarcoma cells. Conclusion COPB2 is highly expressed in human osteosarcoma cell lines, and might be involved in the development of osteosarcoma through cyclins and cell cycle regulation pathway. In addition, COPB2 is associated with neoplasia, invasion and anoikis of osteosarcoma cells.

Background: This retrospective cohort study explores a practical approach to acquiring pathogenic microorganisms in patients with bone and joint infections. Methods: From Aug 2018 to Mar 2022, 68 consecutive patients (87 cultures) with bone and joint infection were recruited in this study. All cultures followed the Peking University First Hospital Procedure of Culturing Pathogenic microorganisms for bone and joint infection. Tissue samples were obtained through fluoroscopy-guided biopsy or open debridement. Tissue samples were divided into manual homogenization (MH), manual mixture (MM), and pathological examination. The baseline, antibiotic exposure, laboratory, surgical, and microbial data were reviewed. Independent sample T-test, Mann–Whitney U-test, and Chi-square test were used to detect the difference between patients who received different processing measures. Results: The average age was 55.8± 2.4 years old. Thirty-nine patients were male. The total positive culture rate of the manual homogenization group was 80.5% (70/87). Thirty-five patients had mixed infections with more than one microorganism cultured. Staphylococci accounted for 60.23% of all microorganisms. Staphylococcus aureus (18.2%) and Staphylococcus epidermidis (15.9%) were the two most common bacteria cultured in this study. Patients with positive culture in the manual mixture group had significantly higher WBC (p = 0.006), NE% (p = 0.024), ESR (p = 0.003), CRP (p = 0.020) and IL6 (0.050) compared to patients with negative culture. After tissue homogenization, only ESR is still statistically different. Patients without SIRS had a low positive culture rate (59.4%). Tissue homogenization could significantly increase the positive culture rate of patients without SIRS. Pre-culture antibiotic exposure was not an independent risk factor for culture results. Conclusion: Peking University First Hospital Procedure for Culturing Pathogenic microorganisms for Bone and Joint Infections was a practical approach for obtaining pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

Objective To evaluate the safety and efficacy of percutaneous vertebroplasty(PVP) in the treatment of spinal metastases with incomplete posterior wall. Methods We retrospectively analyzed 106 spinal metastases patients with incomplete posterior wall treated with PVP. Demographic and pre- and post-operative clinical characteristics were reviewed. Pain relief and functional activities recovery, systemic complications and the local leakage of the bone cement were evaluated before and after operation. Results All patients successfully underwent surgery, VAS score was 3.0(2.0-5.0) after operation and decreased for 5.0(3.0-7.0). Among 70 patients who received the assessment, 10 patients had a better Barthel Index(BI) and 46 patients were with the same activity of daily living. None had systemic complications during the injection of bone cement. Among the 160 vertebrae with incomplete vertebral posterior wall, 39(24.4%) vertebrae showed bone cement leakage and 7(4.4%) vertebrae were intraspinal leakage. None had bone cement leakage-related neurological symptoms after operation. Conclusion Percutaneous vertebroplasty is effective and safe in the treatment of spinal metastases with incomplete posterior wall.

The spine is the most common site of bone metastases. Massive pain, spinal cord compression and neurological dysfunction are common manifestations of spine metastases, negatively impacting the patients' quality of life. Previously, treatment options for spinal metastases, including radiotherapy and surgical treatment, were based primarily on prognostic scores such as Tomita or Tokuhashi. We now have a better understanding of which factors influence survival and quality of life after surgery, and several new techniques have been developed over the past decade to make surgery for spinal metastases safer and more acceptable to patients by decreasing postoperative pain and length of hospital stay. Especially, stereotactic body radiation therapy, minimally invasive techniques and targeted therapy have revolutionized the management of metastatic spine tumors.

The genetic relationships between Coffea arabica resources were analyzed via specific length amplified fragment sequencing (SLAF-seq) and transcriptome sequencing to provide the theoretical basis for breeding new varieties. Twenty C. arabica accessions were used to analyze genetic diversity on the basis of SNPs identified in SLAFs and the transcriptome data. For the SLAF-seq analysis of 20 C. arabica accessions, two Coffea canephora accessions, one Coffea liberica accession, and one Coffea racemosa accession, the number of reads ranged from 2,665,424 to 7,210,310, with a GC content of 38.49%–40.91% and a Q30 value of 94.99%–96.36%. A total of 3,347,069 SLAF tags were obtained, with an average sequencing depth of 13.90×. Moreover, the 1,048,575 SNPs identified in the polymorphic SLAFs were filtered, then the remaining 198,955 SNPs were used to construct a phylogenetic tree, perform a principal component analysis, and characterize the population structure. For the transcriptome analysis, 128.50 Gb clean reads were generated for the 20 C. arabica accessions, with a GC content of 44.36%–51.09% and a Q30 value of 94.55%–95.40%. Furthermore, 25,872 genes' expression levels were used for the correlation analysis. The phylogenetic relationships as well as the results of the principal component analysis, population structure analysis, and correlation analysis clearly distinguished C. arabica Typica-type accessions from the C. arabica Bourbon-type accessions. Notably, several C. arabica local selections with unknown genetic backgrounds were classified according to all four clustering results. [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]

The forest–medicinal plant management system has benefited the commercial production of Amomum villosum. However, little is known about the influence of different forestlands on the cultivation of A. villosum. The present study investigated the potential differences in the A. villosum yield and quality parameters, rhizosphere soil properties, and rhizosphere soil microbiota between a rubber plantation (RP) and a natural secondary forest (NSF). No significant differences in yield or rhizosphere soil properties of A. villosum were observed between RP and NSF, although most of the A. villosum yield parameters, the rhizosphere soil physicochemical properties, and soil enzyme activities were higher in NSF than in RP. Furthermore, the 38 volatile components had significantly higher relative abundances in NSF than in RP. Furthermore, the alpha diversity indices for the microbiota communities in the A. villosum rhizosphere soil indicated that the richness of the bacterial and fungal communities was significantly higher in NSF than in RP. These findings suggest that NSF conditions may be more appropriate than RP conditions for growing A. villosum. The data generated in this study may be useful for increasing the production of high-quality A. villosum via the exploitation of natural environments. [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]

aimed to investigate the effects of manual homogenization on the sensitivity of microbiological culture for patients with pyogenic spondylitis. Methods: From October 2018 to March 2021, patients undergoing fluoroscopy-guided biopsy or open debridement due to pyogenic spondylitis were recruited. Their demographic data and baseline characteristics were recorded. Tissue samples were obtained through fluoroscopy-guided biopsy or open debridement. Tissue samples were divided into three parts: manual homogenization (MH), manual mixture (MM), and pathological examination. Sterile normal saline was set as the negative control to exclude false-positive culture results. The Chi-square test was used to detect the difference of microbiological culture results. Results: Twenty-four consecutive patients (33 tissue cultures) with pyogenic spondylitis treated in our department between October 2018 and March 2021 were recruited in this study. The average age was 61.7± 3.2 years old and 10 patients were female. The MH group had a significantly higher positive rate compared with the MM group in aerobic conditions: 78.8% (26 isolates) vs 54.5% (18 isolates), P=0.037 and anaerobic condition: 63.6% (21 isolates) vs 39.4% (13 isolates), P=0.049. The results of subgroup analyses showed that MH could improve the culture sensitivity for patients with previous antibiotics use and without paravertebral abscesses but not reach a significant level on statistics. Conclusion: Based on the present study, manual homogenization could improve the sensitivity of microbiological cultures for patients with pyogenic spondylitis. [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]

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: This study aimed to evaluate the perioperative safety and efficacy of minimally invasive tubular surgery for patients with spinal metastasis. Methods: A total of 161 consecutive patients with spinal metastasis between June 2017 and June 2020 were retrospectively reviewed. A total of 36 patients were included in this study, 14 patients underwent minimally invasive tubular surgery (M), and 22 patients underwent conventional surgery (C). T-test and chi-square tests were used to evaluate demographic and perioperative data differences between the two groups. Results: Baseline characteristics did not differ significantly between M and C groups except for the SINS (p=0.002) and preoperative Alb (p=0.026). There was no significant difference in operative time and complications between M and C groups (p< 0.05). The M group had less mean blood loss than the C group (1275 vs 718mL, p=0.045). Blood transfusion was comparable between the two groups (p< 0.05). The mean amount and drainage time were lower than the C group (141 vs 873mL, p< 0.001; 3.1 vs 7.0 days, P< 0.001). The mean postoperative hospitalization of the M group was 8.8 days, which was lower than the C group (11.3 days, p=0.045). Sub-analysis showed that for patients with hyper-vascular tumor, the M group had less mean amount and time of drainage compared with the C group (p< 0.05); for patients with hypo-vascular tumor, the mean blood loss and amount of blood transfusion were also reduced in M group (p< 0.05). The mean blood loss and drainage time of patients with hypo-vascular tumors were less than patients with hyper-vascular tumors in the M group (p< 0.05). Conclusion: In selected cases, minimally invasive tubular surgery is safe and effective for patients with spinal metastasis. Patients with hypo-vascular tumors were more suitable for this technique with less blood loss, fewer blood transfusions, minor drainage, and shorter postoperative hospitalization. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to assess the risk variables for predicting intra-spinal canal cement leakage, especially among elderly patients with spine metastases after being treated with percutaneous vertebroplasty (PVP). Furthermore, we proposed and validated a nomogram to stratify risks of intra-spinal canal cement leakage. Methods: We retrospectively analyzed 163 elderly patients (age ≧65 years) with spine metastases who underwent PVP. Patients were randomly divided into a training cohort (n=100) and a validation cohort (n=63). The multivariate logistic regression analysis was used to screen potential risk variables in the training cohort. Significant risk variables were included in the nomogram, and the nomogram was developed according to the estimates of the each included variable. The predictive effectiveness of the nomogram was validated using discrimination and calibration performance. Results: The overall prevalence of intra-spinal canal cement leakage was 9.82% (16/163). In the training cohort, female patients (14.71%, 5/34) showed a higher rate of intra-spinal canal cement leakage as compared with male patients (4.55%, 3/66). The nomogram consisted of sex, cortical osteolytic destruction in posterior wall, and load-bearing lines of spine. The nomogram had acceptable discrimination, with the area under the receiver operating characteristic (AUROC) of 0.75 in the training cohort, 0.64 in the validation cohort, and 0.69 in the entire cohort, and also showed favorable calibration based on the goodness-of-fit test. According to the nomogram, three risk groups were developed: the low risk group had an actual probability of 7.03%, the medium risk group was 11.54%, and high risk group was 44.44%. The difference between the three groups was significant (P ˂ 0.01). Conclusion: Intra-spinal canal cement leakage after PVP is not scarce among elderly patients. We proposed and internally validated a nomogram that is capable of calculating the risk of intra-spinal canal cement leakage among elderly patients with spine metastases. Careful surgical plan should be conducted among patients with a high risk of developing intra-spinal canal cement leakage. [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]

Purpose: The study aims to investigate and compare the efficacy and safety of intraoperative 125I implantation and postoperative irradiation after surgical decompression and stabilization in the treatment of patients with metastatic epidural spinal cord compression (MESCC). Methods: The study retrospectively enrolled 122 MESCC patients treated with surgical decompression and pedicle stabilization combined with 125I brachytherapy (the brachytherapy group) or postoperative radiotherapy (the irradiation group). Operation time, intraoperative blood loss, pain relief, postoperative ambulatory status, postoperative survival outcome, complications, and length of hospitalization were collected and compared between the two groups. Ten potential risk factors were analyzed for postoperative survival outcome. Results: No significant difference was found in baseline characteristics between the two groups (P> 0.05). Postoperative VAS score was significantly decreased, as compared with preoperative scores in both groups (P˂0.001). The VAS in the brachytherapy group was significantly lower than that in the irradiation group at postoperative 1 month, 3 months, and 6 months (P˂0.05). The postoperative ambulatory rates were 90.0% (54/60) in the brachytherapy group and 83.9% (52/62) in the irradiation group (P=0.32). The median overall survival time was similar between the two groups (7.43 months vs 7.27 months, P=0.37). Of all patients in the brachytherapy group, 25.0% (15/60) of patients suffered from complications, while 46.8% (29/62) of patients had complications in the irradiation group (P=0.0086). According to the multiple Cox regression, primary sites (P=0.038), ECOG performance status (P=0.014), and visceral metastases (P=0.0016) showed significance for postoperative survival outcome. Conclusion: Surgical decompression and spine stabilization combined with 125I brachytherapy is a relatively safe and useful method in MESCC patients. [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]

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]

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]