81 research outputs found
Influence of spark plasma sintering and baghdadite powder on mechanical properties of hydroxyapatite
AbstractSince hydroxyapatite-based materials have similar composition and crystallinity as natural calcified tissues, can be used for bone/tissue engineering. In the present study a novel nanocomposite based on bioceramics such as Natural Hydroxyapatite (NHA) and Baghdadite (BAG), was sintered by spark plasma sintering (SPS) technique. The prepared composite was characterized using scanning electron microscopy (SEM), X-ray diffractometer (XRD) and Brunauer–Emmett–Teller (BET) techniques. The porosity of the samples was measured by Archimedes method. The cold crushing strength (CCS) test was applied to evaluate their mechanical properties. Our results demonstrated that NHA-30wt. %BAG nanocomposite specimens have the lower CCS in comparison with other examined composites. Consequently, NHA/BAG samples exhibited acceptable mechanical properties and could be suitable candidates for bone tissue engineering applications especially orthopaedic fields
Effects of cinnamon supplementation on antioxidant status and serum lipids in women with polycystic ovary syndrome
Background The objectives of study were to investigate the effects of cinnamon supplementation on antioxidant status and serum lipids in women with polycystic ovary syndrome (PCOS). Methods This double-blind randomized controlled clinical trial was conducted on 84 overweight or obese PCOS patients; aged 20�38 years. Subjects in cinnamon (n = 42) and placebo (n = 42) groups were given 3 cinnamon capsules (each one contained 500 mg cinnamon) or placebo daily for 8 weeks. Fasting blood samples, anthropometric measurements and dietary intake data were gathered at the beginning and at the end of the study. Independent t test, paired t test and analysis of covariance were used to analyze of data. Results Cinnamon significantly increased serum total antioxidant capacity (P = 0.005). Malondialdehyde was significantly decreased compared with placebo (P = 0.014). Cinnamon supplementation significantly improved serum level of total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol (all P < 0.05). No significant effect was detected on serum triglyceride level. Conclusions Cinnamon supplementation improved antioxidant status and serum lipid profile in women with PCOS and may be applicable for reducing PCOS risk factors. © 2017 Center for Food and Biomolecules, National Taiwan Universit
Effects of cinnamon supplementation on antioxidant status and serum lipids in women with polycystic ovary syndrome
Background The objectives of study were to investigate the effects of cinnamon supplementation on antioxidant status and serum lipids in women with polycystic ovary syndrome (PCOS). Methods This double-blind randomized controlled clinical trial was conducted on 84 overweight or obese PCOS patients; aged 20�38 years. Subjects in cinnamon (n = 42) and placebo (n = 42) groups were given 3 cinnamon capsules (each one contained 500 mg cinnamon) or placebo daily for 8 weeks. Fasting blood samples, anthropometric measurements and dietary intake data were gathered at the beginning and at the end of the study. Independent t test, paired t test and analysis of covariance were used to analyze of data. Results Cinnamon significantly increased serum total antioxidant capacity (P = 0.005). Malondialdehyde was significantly decreased compared with placebo (P = 0.014). Cinnamon supplementation significantly improved serum level of total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol (all P < 0.05). No significant effect was detected on serum triglyceride level. Conclusions Cinnamon supplementation improved antioxidant status and serum lipid profile in women with PCOS and may be applicable for reducing PCOS risk factors. © 2017 Center for Food and Biomolecules, National Taiwan Universit
The impact of laparoscopic ovarian drilling on AMH and ovarian reserve: a meta-analysis
Laparoscopic ovarian drilling (LOD) has been widely used as an effective treatment of anovulatory women with polycystic ovarian syndrome (PCOS). However, there has been a growing concern over a possible damaging effect of this procedure on ovarian reserve. The objective of this study was to investigate the hypothesis that LOD compromises ovarian reserve as measured by post-operative changes in circulating anti-Müllerian hormone (AMH). This meta-analysis included all cohort studies as well as randomised controlled trials (RCTs) investigating serum AMH concentrations and other ovarian reserve markers in women with PCOS undergoing LOD. Various databases were searched including MEDLINE, EMBASE, Dynamed Plus, ScienceDirect, TRIP database, ClinicalTrials.gov and Cochrane Library from January 2000 to December 2016. Sixty studies were identified, of which seven were deemed eligible for this review. AMH data were extracted from each study and entered into the RevMan software to calculate the weighted mean difference (WMD) between pre- and post-operative values. Pooled analysis of all studies (n = 442) revealed a statistically significant decline in serum AMH concentration after LOD (WMD −2.13 ng/mL; 95% confidence interval (CI) −2.97 to −1.30). Subgroup analysis based on duration of follow-up, AMH kit, laterality of surgery and amount of energy applied during LOD consistently showed a statistically significant fall in serum AMH concentration. In conclusion, although LOD seems to markedly reduce circulating AMH, it remains uncertain whether this reflects a real damage to ovarian reserve or normalisation of the high pre-operative serum AMH levels. Further long-term studies on ovarian reserve after LOD are required to address this uncertainty
Investigation of process parameter effect on anisotropic properties of 3D printed sand molds
The development of sand mold three-dimensional printing technologies enables the manufacturing of molds without the use of a physical model. However, the effects of the three-dimensional printing process parameters on the mold permeability and strength are not well known, leading the industries to keep old settings until castings have recurring defects. In the present work, the influence of these parameters was experimentally investigated to understand their effect on the mold strength and permeability. Cylindrical and barshaped test specimens were printed to perform, respectively, permeability and bending strength measurements. Experiments were designed to statistically quantify the individual and combined effect of these process parameters. While the binder quantity only affects the mold strength, increasing the recoater speed leads to both greater permeability and reduced strength due to the reduced sand compaction. Recommendations for optimizing some 3D printer settings are proposed to attain predefined mold properties and minimize the anisotropic behavior of the sand mold in regard to both the orientation and the position in the job box
High resolution seismic stratigraphic analysis: An integrated approach to the subsurface geology of the SE Persian Gulf
Papers included in this dissertation: Paper 1: Farzadi, P. 2006a. The development of Middle Cretaceous carbonate platforms, Persian Gulf, Iran: Constraints from seismic stratigraphy, well and biostratigraphy. Petroleum Geoscience, 12, 59-68. Paper 2: Farzadi, P. 2006b. Seismic facies analysis based on 3D multi-attribute volume classification, Dariyan Formation, SE Persian Gulf. Journal of Petroleum Geology,29/2, 159-174. Paper 3: Farzadi, P. & Hesthammer, J. (Submitted 2006). Diagnosis of the Upper Cretaceous paleokarst and turbidite systems from the Iranian Persian Gulf using volume-based multiple seismic attribute analysis and pattern recognition. N.B.: Originally accepted for publication in the AAPG Bulletin, later rejected because the US government prohibits the publication of papers using Iranian government datasets. The manuscript has been re-submitted to Petroleum Geoscience. Paper 4: Farzadi, P. & Alaei, B. (Submitted 2006). Stratigraphic architecture of the Zagros Basin: towards an objective comparison of the Fold-Thrust Belt and Foreland provinces. Submitted to the Journal of Petroleum Geology; under consideration for a thematic issue. Presentation (at international meeting and on web): Farzadi, P. 2005. Stratal geometries of the Cretaceous carbonate systems: application of multiple volumes attributes analysis to 3-D seismic data from the Persian Gulf. At: Middle to Far East Carbonate Reservoirs: Exploration, Development and Exploitation. PESGB Carbonate conference, 15th & 16th Nov. 2005 London
Premature ovarian failure risk factors in an Iranian population
Alieh Ghassemzadeh1,2, Laya Farzadi1,2, Elaheh Beyhaghi1,21Women&rsquo;s Reproductive Health Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; 2Alzahra University Hospital, Department of Obstetrics and Gynecology, Tabriz University of Medical Sciences, Tabriz, IranBackground: The aim of this study was to determine possible correlates of premature ovarian failure (POF) in an Iranian population.Methods: In a case-control study, 80 patients with POF were compared with 80 controls enrolled from the same setting during 2007&ndash;2008. A food diary was used to assess food consumption habits.Results: Mean age of starting ovarian failure symptoms was 19.3 &plusmn; 5.7 years and mean age of menopause was 22.6 &plusmn; 6.3 years. Familial coincidence was observed in 16 POF patients versus no one in the control group (P &lt; 0.05). POF patients had lower frequency of both eating red meat and fish when compared with controls (P &lt; 0.001). POF and control subjects consumed similar amounts of dairy products, being 5.3 &plusmn; 3.2 times per week in POF and 5.6 &plusmn; 2.1 times in the control groups.Conclusion: In this study, an association between POF and lower red meat or fish consumption was found.Keywords: POF, etiology, case-control, nutrition, premature menopause, premature ovarian dysfunction, primary ovarian insufficienc
Atomic scale melting/solidification behavior and structural evolutions of AlCoCrFeNi high-entropy alloy in selective laser melting process
Comprehension of the evolutions and phenomena that occur on the atomic scale can become a bridge toward a greater understanding of the properties of materials on the macro scale. In this study, molecular dynamics simulations were performed to investigate nano-structural evolutions in the SLM process of the near-equiatomic AlCoCrFeNi high-entropy alloy. Fifteen simulation systems were designed by altering laser power (400–800 eV/ps), scanning speed (0.2–2.0 Å/ps), and hatch spacing (5 and 10 nm) as the process variables for addressing their effects on the structure at the atomic scale. The results showed that the effect of parameters on the atomic displacement is decreased from laser power to scanning speed and hatch spacing, respectively. It was also indicated that the HCP stripes form due to the extreme cooling rates experienced in the process. Furthermore, the reduction of the hatch space can improve the surface quality by spreading the atoms accumulated in the fusion boundary of the previous laser track. These results indicate that controlling volumetric energy density (VED) by lowering laser power and scanning speed as much as possible, is beneficial to obtain the optimum crystal structure of the manufactured parts in this process. Although decreasing the hatch space has no considerable effect on the crystal structure, it can help to achieve a good surface finish which is essential in the SLM industry
Effect of diffusion brazing time on microstructure, isothermal solidification completion and microhardness distribution during joining of Nicrofer 5520 superalloy using a liquated Ni–Cr–B interlayer
In the present study, the effect of time on the microstructural evolution, distribution of elements, type of precipitated phases, and microhardness of diffusion brazed Nicrofer 5520 superalloy using a BNi-9 (Ni–15%Cr–3.7%B) interlayer was investigated. The diffusion brazing was carried out at 1120 °C for seven different holding times by using a 38 μm thick interlayer. The results indicated that the holding time of 30 min was sufficient for complete isothermal solidification. The eutectic gamma solid solution, Ni-rich borides, and Cr–Mo-rich borides were identified near the bond center before the completion of isothermal solidification, (Ni, Mo, Cr)-rich borides and Cr–Ni–Mo–Fe carbides with different morphologies were found in the diffusion affected zone (DAZ). In the holding time longer than 30 min and, the volume fraction of the precipitated phases in the DAZ decreased, and they transformed into rounder particles. Accordingly, the chemical composition of the interlayer became more homogeneous, resulting in a lower DAZ phases’ density that is happened over the higher brazing times. As the holding time was increased, the chemical composition in the interlayer became more similar to the base metal, and the microhardness in the bond zone and its surrounding became more uniform
- …