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Effect of partial rotor-to-stator rub on shaft vibration
Mohamed. A. Abuzaid,Mohamed E. Eleshaky,Mohamed G. Zedan 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.1
The effect of partial rotor-to-stator rubbing is investigated both experimentally and analytically. It is found that due to rubbing the measured vibration signal is distorted showing a flattened portion in the waveform. Spectral analysis indicates that the synchronous component is generally attenuated as a result of rubbing-introduced-friction. It is also indicated that light rubbing induced vibrations are characterized by harmonics at frequencies equal to 1x rev., 2x rev., and 3x rev. Whereas, severe rubbing is identified experimentally by a spectrum containing subharmonics at 1/3 and 2/3 of the rotational frequency. Because of the stiffening effect of rubbing on the rotor, the resonance frequency increases. In general, the analytical results show good agreement with experimental data.
( Saeed Baradwan ),( Sahar Hassan Abdulghani ),( Mohammed Abuzaid ),( Khalid Khadawardi ),( Majed Saeed Alshahrani ),( Abdulrahman Al-matary ),( May A. Alrasheed ),( Najlaa Talat Miski ),( Aroob Abdul 대한산부인과학회 2021 Obstetrics & Gynecology Science Vol.64 No.6
To perform a systematic review and meta-analysis of all randomized controlled trials (RCTs) that investigated the clinical benefits of 17-alpha hydroxyprogesterone caproate (17OHPC) in the prevention of recurrent preterm birth (PTB) among singleton pregnant women with a previous history of PTB. We searched four major databases up till April 2021 and assessed the risk of bias in the included studies. We meta-analyzed various maternal-neonatal endpoints (n=18) and pooled them as mean difference or risk ratio (RR) with 95% confidence interval (CI) using the random-effects model. Six RCTs met the inclusion criteria, comprising 2,573 patients (17OHPC=1,617, control=956). RCTs revealed an overall low risk of bias. The rates of PTB <35 weeks (n=5 RCTs; RR, 0.77; 95% CI, 0.63-0.93; P=0.008), PTB <32 weeks (n=3 RCTs; RR, 0.68; 95% CI, 0.51-0.91; P=0.009), neonates with low birth weight (<2.5 kg) at delivery (n=3 RCTs; RR, 0.63; 95% CI, 0.5-0.79; P<0.001), and neonatal death (n=4 RCTs; RR, 0.41; 95% CI, 0.20-0.84; P=0.02) were significantly reduced in the 17OHPC group compared with the control group. Moreover, 17OHPC treatment correlated with a significantly decreased rate of retinopathy (n=2 RCTs; RR, 0.42; 95% CI, 0.18-0.97; P=0.004). However, there were no significant differences in the rates of neonatal intensive care unit admission, cesarean delivery, and other pretermrelated complications between both the groups. Among singleton pregnant women with a prior history of PTB, 17OHPC may favorably decrease the risks of recurrent PTB and reduce the rate of neonatal death.
Ahmed Abu-Zaid,Saeed Baradwan,Ibtihal Abdulaziz Bukhari,Abdullah Alyousef,Mohammed Abuzaid,Saleh A. K. Saleh,Heba M. Adly,Osama Alomar,Ismail Abdulrahman Al-Badawi 대한산부인과학회 2024 Obstetrics & Gynecology Science Vol.67 No.1
This systematic review and meta-analysis aimed to examine the effect of the antioxidant alpha-lipoic acid (ALA) on various cardiometabolic risk factors and hormonal parameters in patients with polycystic ovary syndrome (PCOS). We searched PubMed, EMBASE, SCOPUS, Cochrane Library, and Web of Science databases without language restrictions until May 2023 to find randomized controlled trials (RCTs) that assessed the impact of ALA supplementation on anthropometric, glycemic, lipid, oxidative stress, and hormonal parameters in women with PCOS. Outcomes were summarized using the standardized mean difference (SMD) and 95% confidence interval (CI) in a random-effects model. An I2 statistic of >60% established significant between-study heterogeneity. The overall certainty of the evidence for each outcome was determined using the grading of recommendations, assessment, development, and evaluations system. Seven RCTs met the inclusion criteria. The ALA group had significant reductions in fasting blood sugar (fasting blood sugar (FBS), n=7 RCTs, SMD, -0.60; 95% CI, -1.10 to -0.10; I2=63.54%, moderate certainty of evidence) and homeostatic model assessment for insulin resistance (homeostatic model assessment of insulin resistance (HOMA-IR), n=4 RCTs, SMD, -2.03; 95% CI, -3.85 to -0.20; I2=96.32%, low certainty of evidence) compared with the control group. However, significant differences were observed between the groups in body mass index, insulin, estrogen, follicle-stimulating hormone, luteinizing hormone, testosterone, low-density lipoprotein, highdensity lipoprotein, triglyceride, total cholesterol, malondialdehyde, or total antioxidant capacity profiles. ALA supplementation improves FBS and HOMA-IR levels in women with PCOS. ALA consumption is an effective complementary therapy for the management of women with PCOS.