Sustained casing pressure (SCP) is a crucial issue in the oil and gas production lifecycle. Epoxy resins, exhibiting exceptional compressive strength, ductility, and shear bonding strength, have the ...potential to form reliable barriers. The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations. This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage. The investigation evaluated the viscosity, compressive strength, and brittleness index of the epoxy resin sealant, as well as its tangential and normal shear strengths in conjunction with casing steel. The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks. The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin, ranging from 1.5 to 6 h, and reduced the initial viscosity from 865.53 to 118.71 mPa⋅s. The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease. The epoxy resin containing 30% curing agent exhibited optimal mechanical properties. After a 14-day curing period, the epoxy resin's compressive strength reached 81.37 MPa, 2.12 times higher than that of cement, whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin. The brittleness index of epoxy resin is only 3.42, demonstrating high flexibility and toughness. The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times, respectively. In a 0.5 mm-wide crack, the injection pressure of the epoxy resin remained below 0.075 MPa, indicating superior injection and flow capabilities. Conversely, the injection pressure of cement surged dramatically to 2.61 MPa within 5 min. The breakthrough pressure of 0.5 PV epoxy resin reached 7.53 MPa, decreasing the crack's permeability to 0.02 D, a mere 9.49% of the permeability observed following cement plugging. Upon sealing a 2 mm-wide crack using epoxy resin, the maximum breakthrough pressure attained 5.47 MPa, 3.48 times of cement. These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.
β-Sialon powders were synthesized via salt-assisted nitridation synthesis from Al, Si, SiO2 powders and molten salt medium (NaCl and NaF) with the addition of different content of NaN3 at different ...temperature for 3 h. NaN3 were employed as auxiliary nitrogen source which effectively provide sufficient nitrogen. The results indicated that the growth of β-Sialon powders had better effect when the NaN3 was added. And the β-Sialon powders grew more completely and the morphology of β-Sialon powders showed the rod-like crystal with hexagonal smooth tips instead of conical tips. In addition, the products displayed different sizes when the content of NaN3 was changed. These results of this work suggested that β-Sialon could be synthesized with specific morphology by adding different content of NaN3.
To explore the association between polycyclic aromatic hydrocarbons (PAHs) exposure and telomere length (TL), so as to investigate the effective biomarkers to evaluate the genetic damage in ...peripheral blood of workers exposed to PAHs.
The exposure group consisted of 145 coke-oven workers (including 30 top-oven workers, 76 side-oven workers and 39 bottom-oven workers), and the non-exposure control group comprised 68 medical staffs. At 6 hours after the weekend duty shift, the samples of urine and 1 ml venous blood were collected from each subject. Airborne benzene-soluble matter (BSM) and particulate-phase B(a)P in the working environment of coke-oven and controls were sampled and analyzed. The concentration of urinary 1-hydroxypyrene (1-OHPyr) was determined. A real-time PCR method was used to determine the relative telomere length (RTL) of genomic DNA in peripheral blood. The relationship between the RTL and external exposure of PAHs, the potential factors which might have influence on TL were analyzed.
The
Rice husk ash is a kind of volcanic ash material with high silicon. This also provides a feasibility for rice husk ash as cement-based auxiliary cementing material. China is rich in rice husk ...resources, and the rice husk ash is stacked. Using rice husk ash (RHA) instead of traditional cementitious materials can effectively solve the environmental pollution caused by the accumulation of rice husk ash. Domestic and international scholar have added rice husk ash as mineral admixture to concrete, but the utilization rate is very low. In order to increase the added value of rice husk ash, the high silicon property of rice husk ash was used to solidify soil. The application range of solidified soil is wide, the requirements for materials are not high, and the functions are different, which can realize the extensive use of rice husk ash. This paper summarizes the literature on comprehensive utilization of rice husk ash at home and abroad, systematically expounds the physicochemical properties and production process of rice husk ash, introduces the application of rice husk ash in solidified soil, and points out the unsolved problems in this field, which provides a direction for the further development.
To investigate the association between the polymorphisms of metabolic genes and telomere length of genomic DNA in peripheral blood of workers exposed to polycyclic aromatic hydrocarbons (PAHs).
One ...hundred and forty five coke-oven workers exposed to PAHs and sixty eight non-exposed medical staffs were recruited in this study. Urinary 1-hydroxypyrene (1-OHP) served as the internal exposure dose of PAHs for all subjects. Relative telomere length (RTL) of genomic DNA in peripheral blood was used as telomere length and measured by real-time PCR. Polymorphisms of metabolic genes were detected by PCR-based methods.
Compared with control group, the exposure group shown a decreased RTL (1.10 +/- 0.75 vs 1.43 +/- 1.06, P < 0.05). In the coke-oven workers, after adjusting the sex, age, cigarettes per day and urinary 1-OHP, RTL (1.25 +/- 0.93) of workers with CT genotype at the CYP1A1 3801 T > C was significantly longer than that (0.93 +/- 0.51) of workers with TT genotype (P < 0.05). RTL (0.90 +/- 0.58) of individuals
During June and July 2003, CO, NO2, THC and PM10 were sampled at the four highway toll gates in Chongqing. Air temperature, air pressure, wind velocity and traffic flow were also monitored ...simultaneously. The relation between air pollution parameters and influencing factors was analyzed by applying the methods of bivariate correlation and partial correlation. As shown in the monitoring result, the outdoor average concentrations of CO and PM10 exceed indoor ones, but NO2 and THC are reverse. The average concentrations of CO and NO2 at the toll gates don't exceed the indoor and outdoor air quality standards except for the toll gate in Chongqing and Chayuan. One-hour average concentrations of outdoor and indoor THC are 7.728 mg/m3 and 7.216 mg/m3 respectively, and exceed ten times of the indoor air quality standard. One-hour average concentrations of indoor and outdoor PM10 change acutely respectively, and the their maximum concentrations are 0.631 mg/m3 and 0.217 mg/m3 which exceed indoor air quality standard a
To seek new effect biomarkers as to evaluating the chromosomal damage in peripheral blood lymphocytes in coke-oven workers who were exposed to polycyclic aromatic hydrocarbons (PAHs).
One hundred and ...fifty-eight coke-oven workers and 69 controls were recruited in this study. Nucleoplasmic bridges and nuclear buds were counted as indicators of chromosomal damage in terms of cytokinesis-block micronucleus (CBMN) test. Occupational history, age, sex, smoking and alcohol using status of all subjects were collected by questionnaire.
Frequencies of nucleoplasmic bridge in coke-oven workers were (9.41 +/- 3.73)% per hundred, and the frequencies of nuclear buds were (7.13 +/- 4.01)% per hundred, which were significantly higher (P < 0.01) than those of controls (1.88 +/- 1.49)% per hundred and (2.20 +/- 1.73)% per hundred respectively. The dose-effect relationships between nucleoplasmic bridges or nuclear buds and PAHs exposure levels were identified. Compared with male coke-oven workers, female workers had less nucle
To compare the effects of Computer-assisted navigation (CAS) and conventional location technique in total knee arthroplasty (TKA).
Eight patients (11 knees) underwent CAS and 9 patients (11 knees) ...underwent conventional location technique for TKA. Follow-up was conducted for 5 - 12 months. The outcomes were compared.
The mechanical axe error of the CAS group was (2.14 +/- 0.25) degrees, significantly less than that of the conventional group (5.12 +/- 2.13) degrees, P = 0.005. The soft tissue balance angle variable of the CAS group was (1.04 +/- 0.18) degrees, significantly less than that of the conventional group (4.12 +/- 1.72) degrees, P = 0.005. The soft tissue separation variable of the CAS group was (3.4 +/- 1.2) mm, significantly less than that of the conventional group (6.1 +/- 2.4) mm, P = 0.005. No fat embolism occurred in these 2 groups. The operating time of the CAS group was (82 +/- 18) min, significantly longer than that of the conventional group (59 +/- 11) min, P = 0.005.
CAS causes mor
To investigate the clinical effects of total knee arthroplasty in treatment of ankylosed knee caused by various reasons.
Four patients with 7 ankylosed knees, caused by ankylosing spondylitis in 1 ...case, septic arthritis with bony ankylosis in 1 case, and rheumatoid arthritis in 2 cases, underwent artificial knee replacement. Before the operation joint activity was 0 degrees , Knee Society score (KSS) was 42 (11 - 63), and the function score was 17. Follow-up was conducted for 5 - 27 months.
Follow-up showed that the average joint activity was raised to 83 degrees (60 degrees - 110 degrees ), KSS score to 83 (64 - 91) points, and function score to 77 points. No infectious case was found.
Total knee arthroplasty has a satisfactory effect in treatment of ankylosed knee. Computer assisted navigation system is helpful in femoro-tibial osteotomy and soft tissue balance. Individualized and directed rehabilitation is a pivotal factor.
To evaluate the associations between genetic polymorphisms of glutathione S-transferase M1 and T1 (GSTM1 and GSTT1), smoking and susceptibility to colorectal cancer.
A case-control study of 126 ...patients and 343 healthy controls was conducted to investigate the role of GSTM1 and GSTT1 polymorphisms in colorectal cancer. Genotypes of GSTM1 and GSTT1 polymorphisms were analyzed by multiplex allele-specific polymerase chain reaction (PCR).
The frequencies of GSTM1 null and GSTT1 null genotypes were 55.5% and 20.4%, respectively. After adjustment for age and sex, among those with GSTT1 null genotype, the GSTM1 null genotype had a significant increased risk of rectal cancers compared to GSTM1 non-null genotype (OR=9.74, 95% CI, 1.13 - 83.85). A 2.22-fold risk of colon cancers was associated with GSTM1 null genotype compared to GSTM1 non-null genotype among current smokers (P >0.05). Individuals with GSTT1 null genotype and currently smoking had a significant risk of colon cancers (OR = 4.55, 95% CI, 1.14 - 18.17),
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