The coupling analysis for the gimbal servo system of a control moment gyroscope considering the influence of a flexible vibration isolator.

To reduce the influence of vibrations generated by the control moment gyroscopes (CMGs), the researchers have put a lot of effort into isolating the vibration between the CMG and the satellite in order to lessen the impact of vibrations produced by the CMGs. The flexibility of the isolator causes the extra degrees of motion for the CMG, which is coupled with the CMG's dynamic behavior and the control performance of the gimbal servo system is therefore changed. However, how the flexible isolator influences the performance of the gimbal controller is uncertain. In this research, the coupling effect on the gimbal closed-loop system is analyzed. Firstly, the dynamic equation of the flexible isolator supported CMG system is established, and a classic controller is used to keep the gimbal speed stable. Secondly, the energy method (the Lagrange equation) is adopted to calculate the deformation of the flexible isolator and the rotation of the gimbal. Based on the dynamic model, the simulation is conducted in the Matlab/Simulink, the frequency and the step response of the gimbal system is employed to better explore the inherent characteristics of the system. Finally, we conduct the experiments on a CMG prototype. The experimental results show that the isolator reduces the response speed of the system. Moreover, the closed-loop system could be unstable due to the coupling relationship between the flywheel and the closed-loop gimbal system. The obtained results would be helpful for the design of the isolator and the optimization of the control system of a CMG.

TSEG-1, a novel member of histone H2A variants, participates in spermatogenesis via promoting apoptosis of spermatogenic cells.

A novel variant of histone H2A, named as testis specific expressed gene 1 (TSEG-1, approved symbol: H2afb1), was identified from adult mouse testis. The TSEG-1 gene is 610-bp in length and consists of one exon. TSEG-1 transcript was robustly and exclusively expressed in adult mouse testis, mainly in spermatocytes. In developmental testis, the TSEG-1 transcript was robustly expressed since postnatal day (P) 21, peaked at P30, and gradually decreased in the testis of aging mouse. The surgical cryptorchidism mouse model showed an increase in the TSEG-1 expression, accompanied by enhanced apoptosis of spermatogenic cells. The EGFP-tagged TSEG-1 protein is located in the nuclei of cultured spermatocytes (GC-2spd cells). Transfection of TSEG-1 into GC-2spd cells resulted in suppressed cell viabilities, increased apoptosis, and decreased mitochondrial membrane potential. Intratesticular injection of TSEG-1 resulted in increased apoptosis of spermatogenic cells in vivo. These results suggest that TSEG-1 may participate in the spermatogenesis via regulating the apoptosis of spermatogenic cells.

Laparoscopic versus open orchiopexy for non-palpable undescended testes in children: a systemic review and meta-analysis.

BACKGROUND: Laparoscopic orchidopexy (LO) has been widespread used in the management of non-palpable testis (NPT) in children. However, the real advantages of LO over traditional open orchidopexy (OO) still remain exclusive. METHODS: Published studies until August 31, 2010 were searched from Medline, Embase, Ovid, Web of Science, and Cochrane databases. Randomized controlled trials (RCTs) and observational clinical studies (OCSs) with a comparison of LO and OO were included for a systemic review and meta-analysis. RESULTS: Out of 226 studies, 2 RCTs and 5 OCSs were eligible for inclusion criteria, comprising 176 cases of LO and 263 cases of OO. The hospital stay of LO was significantly shorter than that of OO (WMD = -0.66; 95% confidence interval [CI] = -0.95 to -0.37; P < 0.00001). However, no significant difference was observed between LO and OO in operative time (WMD = 4.02; 95% CI = -9.89 to 17.93; P = 0.57), time to resume feeding (WMD = -2.29; 95% CI = -6.78 to 2.20; P = 0.32) or full activity (WMD = -9.71; 95% CI = -27.84 to 8.42; P = 0.29), recurrence (OR = 0.60; 95% CI = 0.13 to 2.72; P = 0.51), viable testis rate (OR = 1.61; 95% CI = 0.30 to 8.52; P = 0.58), success rate (OR = 1.41; 95% CI = 0.44 to 4.46; P = 0.56), and testicular atrophy (OR = 1.70; 95% CI = 0.49 to 5.98; P = 0.40). CONCLUSION: Although shorter hospital stay is noted in LO, it does not provide significant advantage over open surgery for treating NPT. However, due to the publishing bias, a series of RCTs are necessary to explore the efficiencies of LO in the management of NPT in children.

Limonene terpenoid obstructs human bladder cancer cell (T24 cell line) growth by inducing cellular apoptosis, caspase activation, G2/M phase cell cycle arrest and stops cancer metastasis.

PURPOSE: The primary purpose of the current study was to investigate the antitumor activity of limonene which is a plant monoterpene along with evaluating its effects on cell apoptosis, cell cycle phase distribution, cell migration and invasion. METHODS: The cell proliferation of T24 bladder cancer cells was examined by WTS-1 assay. The apoptotic effects induced by limonene were investigated by a combination of fluorescence microscopy and flow cytometry and then confirmed by western blot assay. The effects of limonene on cell cycle in T24 bladder cancer cells were studied by flow cytometry. The effects on cell migration and invasion were examined by wound healing assay and transwell assay using Matrigel. RESULTS: The results showed that limonene induced cytotoxic effects and reduced cell viability of T24 human bladder cancer cells showing an IC50 value of 9 µM. Limonene also induced significant apoptosis in bladder cancer cells since it induced significant nuclear fragmentation, chromatin condensation, and splitting of the nucleus, representative of the apoptotic cascade. The apoptotic cell percentage was 1.95, 5.35, 15.61 and 34.71% at limonene concentrations of 0, 9, 18 and 36 µM. Further, the apoptotic effects of limonene were also confirmed by Western blot analysis and the results showed increase in the expression of Bax and caspase-3 and decrease of Bcl-2 expression. Limonene also caused G2/M phase cell cycle arrest as well as suppression of cell migration and invasion. CONCLUSIONS: These results indicate that limonene might be used as a potent anticancer agent against human bladder cancer for which further in depth studies are needed, especially over its toxicological studies.