Search

Hydroxyalkyl-functionalized organosilicon compounds have been prepared from hydrogen-containing organosilicon compounds by hydrosilylation. Various carboxyalkyl-modified organosilicon compounds were then prepared by reacting the hydroxyalkyl-functionalized organosilicon compounds with various cyclic acid anhydrides under solvent and catalyst free. The effects of the nature of the hydroxyalkyl functional groups and the structure of the organosilicon compounds on the ring-opening reaction have been investigated. The synthesized carboxyalkyl-modified organosilicon compounds have been used to treat cotton fabric samples, and the effects of their structures on the softness, whiteness, breaking strength, hydrophilicity, and fiber surface morphology of the cotton have been studied.

Summary The technique of stimulated reservoir volume (SRV) is becoming a key measure to enhance vertical-well productivity and ultimate recovery in tight oil reservoirs. After the SRV treatment, microseismic monitoring results strongly show approximately rectangular stimulated reservoir volumes with a single biwing fracture. However, most published works assumed that the SRV is approximately circular, and few works have considered a rectangular SRV. In this paper, a new analytical pressure-transient solution for vertically fractured wells (VFWs), with rectangular SRV and a single biwing fracture, is derived under constant rate. First, a two-region composite model is established to model the VFW. The inner region is simplified as rectangle dual-porosity with a single biwing fracture. In addition, this model also considers the effect of other multiple factors including stress-sensitivity effect of permeability and unsteady crossflow between matrix and fracture. Then, the trilinear flow model is extended to handle the rectangle boundary and biwing fracture; the Pedrosa's perturbation and Laplace transformation are used to solve the nonlinear equation; the Kazemi's method is adopted to simulate the unsteady crossflow; and the pressure equation for VFW is solved. After that, this analytical solution is applied to a real case from Ordos Basin to conduct equation validation. Finally, sensitivity studies are conducted to evaluate the effect of some critical parameters on the pressure behavior of VFW. The results of model validation show that there is close agreement. Results from this study show that the special flow regimes for a VFW are: (1) linear flow dominated by the biwing fracture with high conductivity, (2) SRV-width-effect flow, and (3) inner boundary-dominated flow. The linear flow is stronger with the increase of biwing-fracture length, biwing-fracture conductivity, and SRV width. As the permeability of SRV increases, the inner boundary-dominated flow becomes more dominant. Moreover, the SRV linear flow will become stronger as the SRV volume increases. This work provides a significant reference for reservoir engineers in pressure-transient analysis as well as fracturing evaluations of vertically fractured wells in tight oil reservoirs.

The complement system plays an important role in cardiovascular disease in patients on hemodialysis. Vascular calcification is also one of the major causes of cardiovascular disease. We want to investigate the relationship between complement activation and vascular calcification in dialyzed patients. One hundred eight hemodialysis patients and 65 heathy controls were enrolled prospectively. Plasma C3a, C5a, mannose-binding lectin (MBL), and membrane attack complex (MAC or C5b-9) levels were detected using ELISA. Plasma C3c, fB, fH, C1q, and C4 levels were measured by immunity transmission turbidity. Abdominal aortic calcification (AAC) was measured by abdomen lateral plain radiograph, and the AAC score was calculated. We identified increased level of MBL and decreased level of C3c and complement factor B compared with normal control. However, C1q, complement factor H, and C4 levels remained at a similar level compared with individuals with normal renal function. The C3a and C5a levels increased, without change of MAC. Forty two of 108 HD patients had the AAC score. C3a levels were correlated with AAC score (r = 0.461, p = 0.002). The median C3a concentration was 238.72 (196.96, 323.41) ng/mL. When evaluated as AAC categories (≤ 4, > 5) with ordinal logistic regression, univariate analyses revealed that higher C3a levels were associated with severe AAC, while multivariate analyses adjusted for age, sex, and calcium level showed that higher C3a levels (OR, 6.28 (1.25–31.69); p = 0.03) were associated with severe AAC. The areas under the curve (AUC) for C3a to diagnose severe abdominal aortic calcification were 0.75(0.58–0.92, 0.01). The complement system was activated in patients on hemodialysis. Higher C3a levels are independently associated with severe AAC. Plasma C3a might have a diagnostic value for the severe AAC in HD patients.

Abstract Storage CO2 in shale formation is considered as a promising option to reduce CO2 emissions and enhance shale gas recovery. Many simple analytical and semi-analytical techniques have been proposed to support screening analysis and performance assessment for potential carbon sequestration sites. However, these analytical techniques have ignored the effect of fracture occurrences, which are important to the carbon sequestration in shale formation. In this paper, numerical simulation technology is applied to model different complex hydraulic fracture occurrences and evaluate the CO2 seepage rule during carbon sequestration. First, multi-component Langmuir isotherm is applied to simulate the adsorption desorption phenomenon of CO2. Combining Langmuir isotherm with the reservoir parameters of Barnett shale formation, shale reservoir simulation model is constructed to simulate the CO2 seepage law during the CO2 sequestration. Then, based on the shale reservoir simulation model, local grid refinement technology is used to characterize the five typical fracture occurrences caused by hydraulic fracturing. Subsequently, the numerical simulation cases with five different fracture occurrences are run to evaluate the performance during CO2 storage process. Finally, some critical important parameters, including engineering and geologic parameters, are evaluated through the sensitivity study. In order to identify and illustrate the performance which progressively occur over time, the log-log plot of CO2 injection rate versus time is adopted. The simulation results indicate that the flow regimes of CO2 injection can be classified into eight flow regions. Among these flow regions, the inner boundary dominated flow regime is a unique one which can occur only when realizing strongly stimulated reservoir volume. Further, the sensitivity study indicates that the fracture topologies and the primary fracture conductivity are the two key factors dominating the early-time flow behavior during the carbon sequestration. And the final-time flow behavior is dominated by the shale reservoir parameters. This work systematically analyzes the effect of fracture topologies on carbon sequestration and enlarges our knowledge of CO2 storage in shale gas systems. 1. Introduction Shale gas has become an increasingly important source of natural gas (CH4) in the United States over the last decade. Due to its unconventional characteristics, injecting carbon dioxide (CO2) to enhance shale gas recovery (CO2-EGR) is a potentially feasible method to increase gas-yield while realizing CO2 sequestration (CS). Therefore, it is more and more important to quantitatively demonstrate the influence of various reservoir and completion parameters on performance of multiply-hydraulic fractured horizontal wells (MFHW) in the process of CO2 injection.

Background: Bioelectrical impedance analysis (BIA) is a promising technique to evaluate dry weight. We compared the dry weight calculated by the three BIA equations Carlo Basile (CB) , Yanna Dou (YD) and the body composition spectroscopy (BCS) with clinical evaluation in maintenance hemodialysis (MHD) patients. Methods: The dry weight of enrolled MHD patients (DWClin) was evaluated under strict clinical surveillance. The whole-body resistances at 50 kHz, intra- and extracellular resistances were measured to calculate the dry weight (DWCB, DWYD and DWBCS) using each of the three equations. Results: Neither DWCB nor DWBCS were statistically different compared to DWClin (DWCB 63.2 ± 17.2 vs. 63.1 ± 16.1 kg; DWBCS 62.8 ± 16.8 vs. 63.1 ± 16.1 kg, p > 0.05). DWYD was significantly lower than DWClin (DWYD 62.0 ± 16.1 vs. 63.1 ± 16.1 kg, p < 0.05). The bias between DWCB and DWClin was the smallest among these three methods (ΔDWCB -0.1 ± 1.4 kg; ΔDWYD 1.1 ± 2.9 kg; ΔDWBCS 0.3 ± 1.8 kg). Conclusion: The CB equations have better consistency with clinical dry weight in MHD patients.

Tight matrix blocks and fractures normally have high stress-sensitivity. In addition, due to the tightness, unsteady cross-flow (UCF) often occurs between matrix and fractures. Those two factors can affect the shapes and characteristics of bottom hole pressure (BHP) and thereby the reliability of well test interpretation. In this study, a physical model of a fractured vertical well with stimulated reservoir volume (SRV) was developed for the purpose of pressure propagation simulation, based on micro-seismic data monitored at SRV fractured vertical wells in different typical tight oil reservoirs. Then a mathematical model was presented to describe BHP of SRV fractured vertical wells by considering stress sensitivity and UCF. Later, the proposed BHP analysis model was applied to a typical SRV fractured vertical well. The results reveal that compared to models without stress sensitivity and UCF, the proposed model can provide more accurate estimates of the inner fractured zone's radius and other relevant reservoir parameters. [Received: March 15, 2017; Accepted: July 17, 2017]

Background. Immune responses are tempered in immunologically privileged sites including the testis. Previous studies have shown that islet transplantation in the testis significantly prolongs islet allograft survival. However, mechanisms underlying testicular immune privilege and intratesticular allograft survival remain unclear. Methods. Allogeneic murine islets were transplanted in the testis. Programmed death-1 ligand-1 (PD-L1) expression was detected by immunohistochemstry and real-time polymerase chain reaction. Infiltrating T-cell proliferation was measured by bromodeoxyuridine uptakes, whereas their apoptosis was quantified by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling methods. Transgenic T cells were used to track allospecific memory T-cell generation. Results. We found that programmed death-1 (PD-1):PD-L1 negative costimulation is essential for prolonged survival of intratesticular islet allografts, as blocking PD-L1 or PD-1, but not PD-L2 and cytotoxic T-lymphocyte antigen 4, abrogated long-term survival of intratesticular islet allografts. As controls, blocking PD-1 or PD-L1 did not significantly accelerate the acute rejection of islet allografts transplanted under the renal capsule, a conventional islet-grafting site. We also found for the first time that PD-L1 is constitutively expressed mainly by spermatocytes and spermatids in seminiferous tubules of the testis. Moreover, infiltrating T cells underwent less vigorous proliferation but faster apoptosis in the testis than in the kidney. Blocking PD-1:PD-L1 costimulation largely abolished the suppression of T-cell proliferation and acceleration of T-cell apoptosis. Importantly, testicular immune privilege significantly suppressed the generation and proliferation of donor-specific memory CD8 + T cells. Conclusions. The constitutive expression of PD-L1 in the testis is an important mechanism underlying testicular immune privilege and long-term survival of intratesticular islet allografts.

We designed a cross-sectional study to investigate plasma vitamin C level in patients who underwent maintenance haemodialysis (MHD) and continuous ambulatory peritoneal dialysis (CAPD) to explore whether there is a difference in vitamin C deficiency between MHD patients and CAPD patients. This investigation included 382 dialysis patients without vitamin C supplement before the study. Demographic characteristics, laboratory tests, ascorbic acid and total plasma vitamin C level were measured. A linear regression model was built to explore the association between vitamin C deficiency and dialysis modalities after adjusting for age, dialysis vintage, gender, Charlson index, modality of dialysis and hsCRP. The range of plasma vitamin C level was from 0.48 µg/mL to 31.16 µg/mL. 35.9% (n = 137) patients had severe vitamin C deficiency (2 µg/mL). Plasma vitamin C level was inversely associated with age and dialysis vintage. After age and dialysis vintage were adjusted, vitamin C deficiency was associated with MHD. R square for model fitting was relatively low, which implied that there were other vitamin C influencing factors not included in the model. Vitamin C deficiency is common in dialysis patients, especially in patients treated with MHD.

Background: We proposed a new method to estimate dry weight (DW) using single frequency bioimpedance. Methods: We hypothesized that the change in whole body resistance at 50 kHz (R50) was proportional to the ultrafiltration volume (UFV) during a hemodialysis (HD) session. When the targeted resistance estimated in healthy subjects was reached, the patient achieved his/her DW. UFV and R50 were monitored in 40 HD patients. Another 43 HD patients were stratified into 2 groups to validate this method. Results: The change in whole body resistance was proportional to UFV in each of the 40 HD patients. In the DWdecrease group, pre-dialysis systolic blood pressure (n = 29, 154.5 ± 22.8 vs. 146.9 ± 22.3, p < 0.05) and antihypertensive medicine (4.7 ± 3.6 vs. 3.3 ± 2.2, p < 0.05) decreased without adverse symptoms change. In the DWincrease group, the number of adverse symptoms in 1 week (n = 14, 26 vs. 6, p < 0.05) decreased without a change in systolic blood pressure. Conclusion: This method may become a convenient and cheaper way to estimate DW in HD patients.