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Tools abrasive wear due to sand particles has caused severe damage during oil and gas exploitation. The friction and wear behaviors of single quartz sand particle against N80 casing steel were investigated to estimate the particle transport resistance and particle abrasive wear behavior using a homemade tribometer in wellbore sand cleanout. Various measurements were conducted to research the impact factor of particle under different water processing condition, dry, short immersion, wet, influences of load and slide velocity. Experimental results indicated that particle-casing friction resistance is mainly formed due to plowing and adhesion effect. Casing transfer and plowing removal are two main damage forms. Particle real contact area increases noticeably after water absorption, which decreases the hertz contact stress and finally produces less plowing depth of casing steel and causes less damage. With load increasing, friction resistance and wear increase with addition of plowing depth. A simple particle-casing friction model was established considering the experimental contact behavior. [ABSTRACT FROM AUTHOR]

Association of expression levels of tumor suppressor proteins p53 and p16 and inflammatory factors in simulated weightlessness with the degree of lumbar disc degeneration of rats was investigated. Magnetic resonance imaging (MRI) examination was performed for rats in control group and experimental group, and the intervertebral disc of rats in both groups was detected and analyzed using hematoxylin and eosin (H&E) histopathological staining. The mRNA expression levels of proinflammatory factors, interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) were detected, and p53 and p16 mRNA and protein expression levels were detected. MRI results showed significant intervertebral disc injury in experimental group. Results of H&E staining revealed that the intervertebral disc injury in experimental group was more serious with obvious signs of degeneration than that in control group. The mRNA expression levels of inflammatory factors (IL-1β, IL-6 and TNF-α) in rats in experimental group were significantly increased compared with those in control group, indicating that the degree of lumbar disc degeneration of rats in simulated weightlessness is closely related to the inflammatory factors. RT-PCR and western blotting proved that both p53 and p16 mRNA and protein expression levels in experimental group were obviously increased. Results of t-test manifested that there were statistically significant differences in p53 and p16 expression levels between control group and experimental group (P<0.01). The abnormal expression levels of p53 and p16 genes have close association with the degree of lumbar disc degeneration of rats in simulated weightlessness, and the lumbar disc degeneration is also closely related to the increased expression levels of inflammatory factors. [ABSTRACT FROM AUTHOR]

Abstract The higher level ab initio methods are performed to reduce an accuracy of three-dimensional adiabatic potential energies. And the accurate numerically fitted method, 3D-spline method, is used to get an accuracy adiabatic potential energy surfaces for the three lowest states of CCO molecule. Starting from reactants, the title reaction through the first two lowest states have no reaction barrier should be very fast. The title reaction pathways should be different depending on the angles that the oxygen atom O(3P) attacked the C 2 ( a 3 Π u ) molecule. If the angles less than 60 ° , the reaction pathway should be O(3P) + C 2 ( 3 Π u ) → CCO( C ∞ ) → CO( X 1 Σ) + C(1D); On the other hand, if the angles great than 65°the transition state should be take into account, the reaction pathway is O(3P) + C 2 ( 3 Π u ) → CCO( C 2 v ) → TS → CCO( C ∞ ) → CO( X 1 Σ) + C(1D). [ABSTRACT FROM AUTHOR]

Abstract Resiniferatoxin (RTX), a selective transient receptor potential vanilloid 1 (TRPV1) receptor agonist, can eliminate TRPV1+ primary sensory afferents and blunt cardiac sympathetic afferent reflex for a relatively long period. The present study determined the effects of intrathecal RTX administration on transverse aortic constriction (TAC)-induced cardiac dysfunction and cardiac remodeling in rats. Five days before TAC, RTX (2 μg/10 μl) was injected intrathecally into the T2/T3 interspace of rats. Cardiac sympathetic nerve activities (CSNAs) and cardiac structure and function were determined eight weeks after TAC. Intrathecal RTX administration abolished TRPV1 expression in the dorsal horn and reduced over-activated CSNA in the TAC rat model. Hemodynamic analysis revealed that RTX reduced left ventricular end-diastolic pressure, indicating the improvement of cardiac compliance. Histologic analysis, real-time reverse transcription-polymerase chain reaction, and Western blots showed that RTX prevented TAC-induced cardiac hypertrophy, cardiac fibrosis, and cardiac apoptosis and reduced the expression of apoptotic proteins and myocardial mRNAs. In conclusion, these results demonstrate that focal chemo-ablation of TRPV1+ afferents in the spinal cord protects the heart from pressure overload-induced cardiac remodeling and cardiac dysfunction, which suggest a novel promising therapeutic method for cardiac hypertrophy and diastolic dysfunction. [ABSTRACT FROM AUTHOR]

Multilayer graphene platelet and expanded graphite were deposited on alumina disk surface and their effects on tribological performance of an alumina–alumina contact in different environments were evaluated using a pin-on-disk tribometer. Experimental results indicate that coefficients of friction at the contact are reduced by deposited particles due to their lubricating effect. It is interesting to find that wear of the contact in dry conditions is less than that under liquid lubrication. Tribofilm plays a key role in the wear reduction performance. In liquid media, however, formation of tribofilm is limited due to fluid flow and formed thin tribofilm is not able to protect the contact from wear. Experimental results show that formation of tribofilm is improved by both multilayer graphene platelet and expanded graphite. This is attributed to the higher adhesion force between graphene and alumina than that between alumina and alumina. The findings demonstrate that deposition of graphene-based materials onto alumina surface hold the promise of providing a new pathway to increase the anti-wear performance of alumina and possibly other ceramics. [ABSTRACT FROM AUTHOR]

Abstract: Bi3+, Sm3+‐activated LiGd5P2O8 (LGPO) phosphors were prepared through high‐temperature solid‐state method. In LGPO host, there are 5 types of Gd crystallographic sites, named as Gd(1)/Gd(2)/Gd(3)/Gd(4), and Gd(5). Bi3+‐activated LGPO phosphors exhibit 1 broad excitation band from 250 to 320 nm centered at 293 nm and a broad asymmetric emission band ranging from 350 to 600 nm with the maximum value approximately at 409 nm. It can be concluded from dual‐emission spectra that Bi3+ may occupy 2 Gd sites and an obvious spectral blue‐shift appeared with increasing Bi3+ content, which is caused by the intensity of crystal field of Bi3+ is decreased. Notably, through the calculation of each Gd‐O chemical parameter, the environmental factor (he) value of each Gd site can be obtained and it can be further inferred that 2 emission bands centered at 409/461 nm are ascribed to Bi3+ ions which occupies Gd(3) and Gd(4) sites, respectively. Energy transfer from Bi3+ to Sm3+ ions in Bi3+/Sm3+ co‐doped LGPO samples occurred and it realizes the color‐tunable emission from cyan to yellow including white‐light emission, through controlling Sm3+ content. Moreover, energy transfer mechanism between Bi3+ and Sm3+ ions is verified to be dipole‐dipole interaction by analyzing the spectroscopic experimental results and the critical distance between them is calculated to be 8.22 Å by concentration quenching method. Finally, it is illustrated that Bi3+ and Sm3+ co‐doped LGPO phosphors will be a promising candidate for n‐UV chip pumped w‐LEDs. [ABSTRACT FROM AUTHOR]

Sand deposition has caused damages to downhole equipment during energy exploitation. The frictional behavior of washing tool against casing under sand condition has been investigated using home-developed tribometer. Experimental results show that friction process has three stages, initial friction, fluctuation friction, stable friction stage. Sand particles get and crush into small during friction process in contact area. The wear rate is inversely related with tool material hardness. The growth rate of tool wear rate decreased with load increasing for surface hardened by small crushed particles indentation, demonstrated by surface morphology and element analysis after test. The wear rate decreased with rotation increasing for more crushed particles indentation. The dominate wear form is abrasive wear and micro-cutting, accompanied with adhesion. [ABSTRACT FROM AUTHOR]

Sustained casing pressure (SCP) caused by tubing leakage is mostly considered as the dangerous situation in gas wells, which is more likely to pose a serious threat to well integrity and environmental protection. In order to assess the downhole risk in early time and further provide maintenance strategies to optimize well performance, it is necessary to diagnose the source of downhole leakage accurately. This paper presents a pressure-balance-based approach for capturing two types of dynamic annulus pressure behaviors in a gas well with SCP caused by tubing leakage at different well depths. The approach includes models that take into account the influence of temperature and pressure distributions of tubing and annulus fluid, which are used to determine tubing leakage points. In addition, such an approach involves the calculation of maximum annulus pressure at the wellhead in a gas well with SCP under four main cases, representing the effects of the leakage location, bottom hole pressure, annulus liquid level and gas production rate on wellhead pressure. Afterwards, an integrated diagnostic testing system has been developed to monitor the synthetic state of annulus fluid and liquid level parameters, ultimately identifying the source of SCP correctly. In contrast to previous works, leakage diagnostic testing can be performed from an offshore platform, and it meets the requirements of offshore field testing and works without a shut-in condition, which is capable of overcoming limitations of downhole detection. A case study focused on an offshore gas well with SCP is presented to illustrate the feasibility of the proposed approach, and also to demonstrate that leakage diagnosis contributes to the mechanism investigation of SCP, as well as the design improvement of gas wells integrity. [ABSTRACT FROM AUTHOR]

The aim of the present study was to reveal the potential hub genes and regulatory mechanisms associated with senescence in human annulus cells by analyzing microarray data using bioinformatics. The gene expression dataset GSE17077, of senescent and non‑senescent annulus cells obtained from patients with disc degenerative diseases (DDD), was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified. Functional and pathway annotations were performed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes terms, respectively. Web‑based Gene Set Analysis Toolkit and Chip Enrichment Analysis were used to identify key transcription factors (TFs). A protein‑protein interaction (PPI) network was constructed to analyze the hub genes associated with senescence in DDD. A total of 667 DEGs were screened, including 368 up‑ and 299 down‑regulated genes. These DEGs were enriched in phosphorylation, regulation of apoptosis and regulation of programmed cell death. In addition, DEGs were involved in axon guidance, natural killer cell‑mediated cytotoxicity, purine metabolism and the mitogen‑activated protein kinase (MAPK) signaling pathway. The TFs activator protein 1 (AP1), specificity protein 1 and aryl hydrocarbon receptor may serve regulatory roles in gene expression in senescent cells. Certain key target genes of TFs, including heat shock protein 90 (HSP90) and C‑X‑C motif chemokine 5 (CXCL5), within the DEGs were revealed to have a high connectivity degree by PPI analysis. The results of the present study indicated that the MAPK‑regulated AP1 pathway may contribute to senescence‑associated disc degeneration. The DEGs, including HSP90 and CXCL5, with a high degree of connectivity may be potential targets for future investigations into molecular biomarkers. [ABSTRACT FROM AUTHOR]

Materials working in slurries containing seawater and abrasive particles degrade gradually because of the synergic effects of mechanical wear and electrochemical corrosion. In this study, the abrasion–corrosion behaviors of a steel–steel tribopair in an environment with artificial seawater and SiO2/Al2O3particles were investigated. Corrosion is responsible for surface degradation at low concentrations of SiO2particles, whereas abrasion is the primary cause for steel damage at high SiO2concentrations. When Al2O3particles were used, abrasion was found to be the dominant factor for material loss at all concentrations. Results from this study indicate that at low concentrations of hard particles, abrasion–corrosion behavior is determined by the properties of particles. [ABSTRACT FROM AUTHOR]

Purpose With the rapid development of rail transportation and energy-delivery systems, such as buried oil and gas pipelines and high-voltage transmission lines, the alternating current (AC) corrosion of buried steel pipelines is becoming more serious. This paper aims to study the corrosion behaviours of Q235 buried steel pipelines induced by the alternating stray current, with a set of indoor simulated experiment apparatuses.Design/methodology/approach The corrosion of the coating holidays of the buried steel pipelines at various AC current densities from 0 to 200 A/m2 in the soil-simulating environment was revealed by the electrochemical and weight-loss methods.Findings The results showed that the corrosion potential of the steel shifted negatively obviously and the corrosion rate of the steel increased with the increasing of AC current density. At a low AC current density, the negative deviation of the corrosion potential of the steel was small and the increase of corrosion rate was slight. However, the negative deviation of the corrosion potential was remarkable and the corrosion rate was greatly increased at a relative higher AC current density. The geometrical shape of the corrosion images indicated the corrosion forms changed from uniform corrosion to local corrosion due to the increase of AC interference.Originality/value Investigation results are of benefit to provide a new strategy to forecast and evaluate the AC-induced corrosion of the buried pipelines which could improve the safety of pipeline transportation. [ABSTRACT FROM AUTHOR]

Frictional behavior of wax-oil gels against steel has been investigated using a homemade tribometer to estimate the frictional resistant force produced by wax plugs in pipelines pigging. Experimental results show that there are several impact factors on frictional behavior of wax-oil gels against steel, including wax concentration, normal force and velocity. Coefficient of sliding friction increases with wax concentration. Normal load and velocity have opposite impacts on the coefficient of sliding friction. The outflow mineral oil has an important impact in the frictional process. A mechanism model of wax-oil gels against steel is built based on the results. [ABSTRACT FROM AUTHOR]

Purpose The wax deposition in oil wells and pipelines is very viciously negative to the petroleum extraction and crude oil transportation, and it even causes severe blockage accident. This study aims to describe cleaning experiments performed on wax deposition of different deposition layer and experimental conditions to investigate the removal and tribological properties and chip formation.Design/methodology/approach An optical arrangement was used to visually record the cleaning process, whereas the friction forces were measured by a custom-built tribometer. Various measurements were performed with tool rake angles of 45° and −30° and cleaning depths from 1 to 5 mm.Findings Results from experiments and modeling suggest that the transition of chip was dependent on rake angle, wax performance and cleaning depth. While the cleaning depth increased, the friction and cleaning resistant force also increased. With the increase of cleaning depth, the wax layer cleaning quantity increased and the chip strengthened; hence, the curvature radius of chip was enhanced to form platy chip. The chip of wax–oil mixture was discontinuous units, and it was easy to adhere on the rake face with the increasing depth of cut. With an increase in cleaning depth, the friction and cleaning-resistant force also increased.Originality/value It is concluded that for effectively cleaning and stabilizing of pipeline cleaning machine, different cleaning parameters should be applied to accommodate wax layer or wax–oil mixture. [ABSTRACT FROM AUTHOR]