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In order to design a quartz accelerometer with high-precision vibration characteristics and strong resistance to external shock, a novel double-ended tuning fork quartz accelerometer that combines the well-known principles of the tuning fork techniques is developed. The mechanical structure of the double-ended tuning fork quartz accelerometer comprises of a pair of double-ended tuning forks, one damping plate and two covers. The operating principle of the double-ended tuning fork quartz accelerometer with two quartz tuning forks in push-pull configuration is described. The output difference frequency of the double-ended tuning fork accelerometer is proportional to the input acceleration. The dimension of the double-ended tuning fork and the flexural support are designed. The stress simulation experiment of the double-ended tuning fork quartz chip are carried out by FEM (Finite Element Method) Using ANSYS software and the result of the stress simulation experiment indicates that the value of the most axial tension and the most axial pressure are both 2.23 × 106N/m2, and less than the maximum safe stress of the quartz.

The paper analysis the yunguang UHVDC system requires exchanging reactive power with AC busbar while transmitting active power. In order to satisfy the operation requirement of converter station under different AC and DC operation modes, the paper centers on switching AC filter and reactive power values under different active power transmission, operate modes and DC voltages. The conclusion has been applied in yunguang UHVDC and is very useful for the UHVDC project.

The performance of silicon micro-gyroscope (SMG) is influenced deeply by quadrature error and offset error. The reasons for inducing quadrature error and offset error are analyzed and the expressions of quadrature error and offset error are enduced. In order to eliminate the effects of the quadrature error and offset error, as well as the inherent non- linearity in the capacitance-type sensors, a closed-loop feedback control circuit with quadrature correction is designed. The opened-loop detecting circuit is also presented because the closed- loop control approach is motivated by special features of opened- loop detecting. The designed principle of frequency difference deltaf between drive mode and sense mode, as well as quality factor Qy, is brought forward. The results of the experiment indicate that the quadrature error and offset error are corrected. By comparing with opened-loop detecting, the closed-loop feedback control circuit with quadrature correction decreases the non- linearity of scale factor from 16.02% to 0.35%, widens the maximum rate capability from plusmn270deg /s toplusmn 370deg /s and increases the stability of zero bias by 2.5 times.

We investigated the effects of celecoxib on the cell proliferation and the expression and activity of P-glycoprotein in the human gastric carcinoma multidrug resistance sublines SGC7901/adriamycin and SGC7901/vincristine. The cell proliferation was measured by [3H]thymidine incorporation assay and MTT test. The expression of the multidrug resistant gene (MDR1) was detected by real-time quantitative reverse transcription-polymerase chain reaction. P-glycoprotein was measured by Western blot analysis. The intracellular rhodamine 123 accumulation was analyzed by flow cytometry to evaluate the activity of P-glycoprotein. After treatment with celecoxib, the proliferation inhibitions of SGC7901 cell line and the SGC7901/adriamycin and SGC7901/vincristine sublines increased linearly in a positive dose-dependent pattern in both the [3H]thymidine incorporation assay and in the MTT test. The IC50 value of the MDR1/GAPDH ratio was 5.50 x 10(-6) mol/l in SGC7901/adriamycin and 3.89 x 10(-6) mol/l in SGC7901/vincristine. P-glycoprotein expression levels in the two multidrug resistance sublines treated with celecoxib were significantly lower than those in control groups, 0.28 vs. 0.71 in the SGC7901/adriamycin subline and 0.21 vs. 0.83 in the SGC7901/vincristine subline, respectively, P

This study was conducted to assess the growth inhibition of colorectal adenoma cells by sulindac and identify the possible mechanisms.The colorectal adenoma cells from human sporadic adenomatous polyps were cultured, and then treated with sulindac. The cell viability was examined by MTT colorimetric assay; the S-phase fraction and the percentage of apoptosis were measured by flow cytometry.Following sulindac treatment at different concentrations for 24, 48 and 72 hours, reduction of the cell viability was time- and dose-dependent. After 48-hour-treatment, S-phase fraction was decreased and the percentage of apoptosis was increased; both indexes of all groups except 0.3 mmol/L group were different from those of controls (P0.05).These data suggested that sulindac could inhibit the growth of the colorectal adenoma cells, and its mechanisms might be related to suppressing proliferation and inducing apoptosis.

This paper investigates temperature compensation methods used for the scale factor and bias of the MEMS gyroscope within the temperature range from − 40°C to 60°C. The structure and periphery monitor circuit are introduced. Then the determinant elements of the MEMS gyroscope's scale factor are analysed and the results indicate that scale factor is directly proportional to drive amplitude and sense loop gain and is inversely proportional to the frequency gap between two modes. After that, the compensation methods are proposed, the thermal resistor's positive temperature coefficient (tempco) is utilized to calibrate the scale factor's tempco through regulating the drive mode amplitude and the sense loop gain, and each method is applied respectively and the results are contrasted. The test results of the two specimens express that the most effective compensation method could decrease the scale factor's tempco from 693ppm/°C (640ppm/°C) to 250ppm/°C (257ppm/°C), improving it by 63.9% (59.8%). Finally, a method of declining bias's tempco is investigated and implemented after scale factor compensation. A summator with a thermal resistor is utilized at the output level and decreases the bias's tempco from 103.89°/h/°C (100.78°/h/°C) to 9.70°/h/°C (12°/h/°C) improving it by 90.7% (88%). Repeat tests are performed based on two specimens to prove the repeatability and reproducibility of the methods.

In this paper, we report a novel double-ended tuning fork (DETF) with variable sections. The DETF is fabricated using a quartz micro-electro-mechanical system (MEMS) technique and packaged using the flip chip technique. The central part of the vibration beam is thinned to enhance the force-frequency sensitivity but not decrease the vibration frequency. The mechanical quality factor (Q value) can also be maintained, which determines the mechanical noise performance. Three types of DETF are designed and fabricated with a fixed beam length of 4 mm. The vibration characteristics (vibration frequency, Q value, and equivalent circuit parameters) are evaluated using an impedance analyzer 4294A. The finite element method (FEM) is used to simulate the natural frequency and force-frequency sensitivity. For the natural frequencies, the experimental results agreed well with the simulation results. High Q values are achieved for all the DETFs, which are 9924, 7083, and 6335. By multiplying the force-frequency sensitivity (ΔF) by the measured Q values, the performance of the new DETF structure can be improved by 1.9 times.

Background Anopheles sinensis is a primary vector for Plasmodium vivax malaria in most regions of China. A comprehensive understanding of genetic variation and structure of the mosquito would be of benefit to the vector control and in a further attempt to contribute to malaria elimination in China. However, there is only inadequate population genetic data pertaining to An. sinensis currently. Methods Genetic variations and structure among populations of An. sinensis was examined and analyzed based on the nucleotide sequences of a 662 nt variable region of the mitochondrial cox1 gene among 15 populations from 20 collection sites in China. Results A total of 453 individuals in 15 populations were analyzed. The cox1 gene sequences were aligned, and 247 haplotypes were detected, 41 of these shared between populations. The range of haplotype diversity was from 0.709 (Yunnan) to 0.998 (Anhui). The genealogic network showed that the haplotypes were divided into two clusters, cluster I was at a high level of homoplasy, while cluster II included almost all individuals from the Yunnan population. The Yunnan population displayed a significantly high level of genetic differentiation (0.452−0.622) and a restricted gene flow with other populations. The pairwise F ST values among other populations were lower. The AMOVA result showed that the percentage of variation within populations (83.83%) was higher than that among populations (16.17%). Mantel test suggested that geographical distance did not significantly contribute to the genetic differentiation (R 2 = 0.0125, P = 0.59). Neutral test and mismatch analysis results showed that the An. sinensis population has undergone demographic expansions. Conclusions Anopheles sinensis populations showed high genetic polymorphism by cox1 gene. The weak genetic structure may be a consequence of low genetic differentiation and high gene flow among populations, except the Yunnan samples. The Yunnan population was isolated from the other populations, gene flow limited by geographical distance and barriers. These findings will provide a theoretical basis for vector surveillance and vector control in China. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2013-z) contains supplementary material, which is available to authorized users.