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We performed ultrasonic experiments in specimens from a tight oil reservoir. The P-wave attenuation of fluid-saturated specimens was estimated by the spectral ratio method. The results suggest that at ultrasonic frequencies, most specimens have stronger attenuation under gas-saturated conditions than at water- or oil-saturated conditions. The P-wave attenuation positively correlates with permeability. Scanning electron microscopy observations and the triple-porosity structure model were used to simulate the wave propagation. The P-wave velocity dispersion and attenuation are discussed on the basis of the Biot, Biot-Rayleigh double-porosity medium, and the triple-porosity structure models. The results suggest that the Biot and Biot-Rayleigh models cannot explain the attenuation, whereas the triple-porosity structure model is in agreement with the experimental data. Furthermore, we infer that microcracks are common in a porosity of 5%–10%, and the size of microcracks increases in samples with higher porosity. However, the volume ratios of microcracks and clay inclusions remain constant regardless of porosity variations. The size of microcracks is significantly larger than the clay inclusions, and the bulk modulus of microcracks is lower than the bulk modulus of clays. [ABSTRACT FROM AUTHOR]

A new non-linear transverse-torsional coupled model was proposed for 2K-H planetary gear train, and gear's geometric eccentricity error, comprehensive transmission error, time-varying meshing stiffness, sun-planet and planet-ring gear pair's backlashes and sun gear's bearing clearance were taken into consideration. The solution of differential governing equation of motion was solved by applying variable step-size Runge-Kutta numerical integration method. The system motion state was investigated systematically and qualitatively, and exhibited diverse characteristics of bifurcation and chaos as well as non-linear behavior under different bifurcation parameters including meshing frequency, sun-planet backlash, planet-ring backlash and sun gear's bearing clearance. Analysis results show that the increasing damping could suppress the region of chaotic motion and improve the system's stability significantly. The route of crisis to chaotic motion was observed under the bifurcation parameter of meshing frequency. However, the routes of period doubling and crisis to chaos were identified under the bifurcation parameter of sun-planet backlash; besides, several different types of routes to chaos were observed and coexisted under the bifurcation parameter of planet-ring backlash including period doubling, Hopf bifurcation, 3 T-periodic channel and crisis. Additionally, planet-ring backlash generated a strong coupling effect to system's non-linear behavior while the sun gear's bearing clearance produced weak coupling effect. Finally, quasi-periodic motion could be found under all above-mentioned bifurcation parameters and closely associated with the 3 T-periodic motion. [ABSTRACT FROM AUTHOR]

A new non-linear bending-torsional coupled model for double-row planetary gear set was proposed, and planet's eccentricity error, static transmission error, and time-varying meshing stiffness were taken into consideration. The solution of differential governing equation of motion is determined by applying the Fourier series method. The behaviors of dynamic load sharing characteristics affected by the system parameters including gear eccentricities error, ring gear's supporting stiffness, planet's bearing stiffness, torsional stiffness of first stage carrier and input rotation rate were investigated qualitatively and systematically, and sun gear radial orbits at first and second stage were explored as well. Some theoretical results are summarized as guidelines for further research and design of double-row planetary gear train at last. [ABSTRACT FROM AUTHOR]

A new nonlinear transverse-torsional coupled model with backlash and bearing clearance was proposed for planetary gear set. Meanwhile, sun gear and planet's eccentricity errors, static transmission error, and time-varying meshing stiffness were taken into consideration. The differential governing equations of motion were solved by employing variable step-size Rung-Kutta numerical integration method. The behavior of dynamic load sharing characteristics affected by the system parameters including input rate, sun gear's supporting stiffness and eccentricity error, planet's eccentricity error, sun gear's bearing clearance, backlashes of sun-planet and planet-ring meshes were investigated qualitatively and systematically. Some theoretical results are summarized at last which extend the current understanding of the dynamic load sharing behavior of planet gear train, enrich the related literature and provide references for the design of planetary gear train. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the vibration transmissibility characteristics of the undamped and damped smart spring systems. The frequency response characteristics of them were analyzed by using the equivalent linearization technique, and the possible types of the system motion were distinguished by using the starting and ending frequencies. The influences of system parameters on the vibration transmissibility characteristics were discussed. The following conclusions may be drawn from the analysis results. The undamped smart spring system may simultaneously have one starting frequency and one ending frequency or only have one starting frequency, and the damped system may simultaneously have two starting frequencies and one ending frequency. There is an optimal control parameter to make the peak value of the vibration transmissibility curve of the system be minimum. When the mass ratio is far away from the stiffness ratio, the vibration transmissibility is small. The effect of the damping ratio on the system vibration transmissibility is significant while the control parameter is less than its optimal value. But the influence of the relative damping ratio on the vibration transmissibility is small. [ABSTRACT FROM AUTHOR]

Behcet's disease (BD) accompanied by intestinal involvement is called intestinal BD. Although recent studies have attained positive feedback with the administration of anti-TNF-α agents in patients with BD, only a few reports on the study of etanercept in intestinal BD have been found. In this study, 35 cases of intestinal BD were treated with conventional therapy (prednisone or methotrexate) for a minimum period of 3 months (group 1). Another 19 patients who failed to respond to conventional therapy were then treated with etanercept (25 mg twice a week for 3 months). During each subsequent relapse, the patients were given the same treatment. The main outcome measures were the four criteria for diagnosis of BD (buccal ulcers, genital ulcers, ocular lesions, and skin lesions), the manifestation of intestinal involvement (abdominal symptoms, double-balloon enteroscopy), laboratory examinations of the acute phase reactants (erythrocyte sedimentation rate) and C-reactive protein, and relapses. As a result of the administered therapy, the healing rate of buccal and genital ulcers, the remission rate of ocular lesions, skin lesions, and abdominal symptoms, the healing rate of intestinal ulcers, and the recovery rate of ESR and CRP were significantly higher in group 2 than those of group 1. The relapse rate in the etanercept therapy was reduced significantly when compared with conventional therapy group. In conclusion, etanercept treatment, in contrast to the conventional therapy, can result in better curative effect and less adverse reactions in intestinal BD. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the profiles change in proanthocyanidins (PAs) catalyzed by polyphenol oxidase (PPO) from lotus seedpod in a model wine system (MWS). Results showed that PAs from lotus seedpod consisted of dimer (74.00 %) and trimer (22.75 %). PPO could tolerate ethanol concentrations below 20 % (v/v). The optimum temperature of PPO activity was 80 °C, and the optimal pH was 9.0. Its molecular weight was approximately 31 kDa, and its secondary structures were α-helix (59.0 %), β-sheet (4.3 %), turns (14.1 %), and random coils (22.6 %). In the MWS, the trimers gradually increased from 22.55 % at 0 h (control) to 100 % at 10 h incubation, while the dimers decreased from 74.33 % (control) to 0 % at 10 h incubation. Moreover, the composition of the precipitate formed at different incubation time points was approximately 16.54 % of monomers, 21.03 % of dimers, and 62.43 % of trimers at 2 h incubation with PPO. The results from this study have provided in vitro evidence for a possible application of PPO in red wine aging. [ABSTRACT FROM AUTHOR]

Recently, stathmin 1 has been proposed to function as an oncogene based on some relevant studies in multiple types of human cancers. However, the role of stathmin 1 in gastric cancer carcinogenesis has not been elucidated yet. The aim of this study was to investigate the expression of stathmin 1 as well as its association with overall survival of gastric cancer patients. The expression of stathmin 1 was detected by real-time quantitative reverse transcription polymerase chain reaction and Western blotting in gastric cancer and adjacent nontumor tissues. In addition, stathmin 1 expression was analyzed by immunohistochemistry in paraffin samples from 210 primary gastric cancer patients. The expression levels of stathmin 1 mRNA and protein in gastric cancer tissues were both significantly higher than those in adjacent nontumor tissues. In addition, the expression of stathmin 1 is correlated with Lauren's classification, depth of invasion, lymph node metastases, and tumor node metastasis (TNM) stage (all P < 0.05). Univariate analysis showed that high stathmin 1 expression was associated with poor prognosis in gastric cancer patients ( P = 0.040). Multivariate analysis demonstrated that only lymph node metastasis and TNM stage were the independent prognostic indicators for gastric cancer. Stathmin 1 expression status is not an independent prognostic factor for patients with gastric cancer. Further subgroup analysis revealed that stathmin 1 expression was significantly correlated with prognosis in diffuse type gastric cancer. This research showed that the stathmin 1 overexpression might play an important role in the pathogenesis and subsequent progression of gastric cancer. Stathmin 1 could also be a potential therapeutic target in gastric cancer, especially for diffuse type gastric cancer. [ABSTRACT FROM AUTHOR]

Prokaryotic expression vectors pET32a (+)-hIL-2-Luffin P1 and pET32a(+)-Luffin P1 were constructed by gene engineering, followed by induced expression, purification and identification of hIL-2-Luffin P1 and Luffin P1. Hut-78 cells were treated with hIL-2-Luffin P1 and arotinoid ethylester at the different concentrations for the different time periods. The proliferation inhibition rate of Hut-78 cells was determined by MTT assay, and early apoptosis of Hut-78 cells was detected. The fusion protein hIL-2-Luffin P1 with high biological activity was obtained. Treatment of Hut-78 cells for 48 h with hIL-2-Luffin P1, and with hIL-2-Luffin P1 and arotinoid ethylester at different concentrations suggested that the cell proliferation inhibition and apoptosis rates were time- and concentration-dependent. The recombinant immunotoxin hIL-2-Luffin P1 was successfully constructed, which provides an experimental basis for further study of the effect of this immunotoxin on cutaneous T cell lymphomas. [ABSTRACT FROM AUTHOR]

A nonlinear lateral-torsional coupled vibration model of a planetary gear system was established by taking transmission errors, time varying meshing stiffness and multiple gear backlashes into account. The bifurcation diagram of the system's motion state with rotational speed of sun gear was conducted through four steps. As a bifurcation parameter, the effect of rotational speed on the bifurcation properties of the system was assessed. The study results reveal that periodic motion is the main motion state of planetary gear train in low speed region when n<2 350 r/min, but chaos motion state is dominant in high speed region when n>2 350 r/min, The way of periodic motion to chaos is doubling bifurcation. There are two kinds of unstable modes and nine unstable regions in the speed region when 1 000 r/min n<3 000 r/min. [ABSTRACT FROM AUTHOR]

stepwise strategy is reported for the design of a meditor-free amperometric tyrosinase biosensor. It is based on the azide-alkyne click reaction and carbodiimide coupling. Firstly, azide-terminated alkane thiols monolayers were self-assembled on the Au electrode surface. Then, nitrophenyl groups were covalent attached to the self-assembled monolayers (SAMs) via the click reaction of copper(I)-catalyzed 1,3-dipolar cycloadditions of azide-alkyne. Finally, the nitrophenyl group terminated SAMs were converted to aminophenyl-terminated interface by electrochemical reduction, and tyrosinase was covalent immobilized onto the Au electrode via carbodiimide reaction. Based on the stepwise strategy, a meditor-free amperometric tyrosinase biosensor was farbricated, and it showed good electrocatalytic reduction ability toward phenol, pyrocatechol and m-Cresol. Their linear ranges were over the range of 0.2 to 15.0 μmol·L, 0.2 to 73.0 μmol·L, and 0.2 to 33.0 μmol·L, respectively. [ABSTRACT FROM AUTHOR]

Because rigidity of either hub or rim of diaphragm coupling is much greater than that of the disk, and asymmetrical bending is under the condition of high speed revolution, an assumption is made that each circle in the middle plane before deformation keeps its radius unchanged after deformation, but the plane on which the circle lies has a varying deflecting angle. Based on this assumption, and according to the principle of energy variation, the corresponding Euler’s equation can be obtained, which has the primary integral. By neglecting some subsidiary factors, an analytic solution is obtained. Applying these formulas to a hyperbolic model of diaphragm, the results show that the octahedral shear stress varies less along either radial or thickness direction, but fluctuates greatly and periodically along circumferential direction. Thus asymmetrical bending significantly affects the material’s fatigue. [ABSTRACT FROM AUTHOR]