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Coating of Laponite on PLA Nanofibrous for Bone Tissue Engineering Application
Zahra Orafa,Shiva Irani,Ali Zamanian,Hadi Bakhshi,Habib Nikukar,Behafarid Ghalandari 한국고분자학회 2021 Macromolecular Research Vol.29 No.3
In this study, electrospun polylactic acid (PLA) nanofibers were coated with osteoinductive Laponite (LAP) nanoplatelets and used as scaffolds for bone tissue engineering. The LAP nanoplatelets were physically crosslinked with high molecular weight polyethylene oxide (PEO) to make a layer of LAP/PEO network around PLA nanofibers with a thickness of 45-175 nm that was controllable through adjusting the concentration of the LAP/PEO solution (0.4, 0.8, and 1.2 wt%). The LAP/PEO layer improved the surface hydrophilicity (water contact angle from 111° to 26°) and thus the cell attachment and proliferation (p ≤ 0.05) by the scaffolds. The LAP nanoplatelets coated on the surface of PLA nanofibers could induce osteodifferentiation on human mesenchymal stem cells (hMSCs) by increasing the ALKALINE PHOSPHATASE (ALP) activity. The expression of specific osteogenic genes (ALP and OSTEONECTIN) at the transcription level (p ≤ 0.001) for the seeded hMSCs proved the osteoinductive effect of coated LAP nanoplatelets for the differentiation of stem cells to osteoblasts without using any external osteogenic inducers. The LAP-coated nanofibers can be used as an excellent scaffold for bone tissue engineering to provide an appropriate environment for direct bone tissue engineering.
Ghasemi Arman,Ramazani Mazaher,Bakhshi Saeed Reza,Al-Khafaji Ali Hussein Demin,Zahabi Saeed,Loghman Estarki Mohammad Reza,Zamani Abbas 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.4
This research aims to fabricate and develop a composite brake disc made of carbon/silicon carbide. For this purpose, the first silicon carbide nanoparticles were ultrasonicated with alumina sintering aid and carbon fi ber (between 10 and 20%) with different lengths of 3 mm, 10 mm, and 15 mm. Next, the fi nal Cf/SiC composite bulk was made-up via the spark plasma sintering (SPS) method. After that, the effect of different lengths of carbon fiber was explored on the porosity, coefficient of friction, fracture toughness, thermal conductivity, and microhardness of samples. The results showed that the density of sintered samples with a carbon fiber length of 10 mm was higher than that of samples with fiber lengths of 3 and 15 mm. Also, the hardness (25.79 GPa) and fracture toughness (5.72 MPa.m 1/2) of this sample were higher than those of the samples sintered with carbon fiber lengths of 3 and 15 mm. Further, this sample with the maximum density showed a coefficient of friction (COF) of 0.43. Since for aeroplane brake discs, the COF should be between 0.3 and 0.4, and the porosity of sam- ples should range within 3–5%, the samples sintered with the carbon fiber length of 10 mm had the nearby features to the preferred air brake disc indices.
Self-powered hybrid electromagnetic damper for cable vibration mitigation
Maziar Jamshidi,C.C. Chang,Ali Bakhshi 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.20 No.3
This paper presents the design and the application of a new self-powered hybrid electromagnetic damper that can harvest energy while mitigating the vibration of a structure. The damper is able to switch between an energy harvesting passive mode and a semi-active mode depending on the amount of energy harvested and stored in the battery. The energy harvested in the passive mode resulting from the suppression of vibration is employed to power up the monitoring and electronic components necessary for the semi-active control. This provides a hybrid control capability that is autonomous in terms of its power requirement. The proposed hybrid circuit design provides two possible options for the semi-active control: without energy harvesting and with energy harvesting. The device mechanism and the circuitry that can drive this self-powered electromagnetic damper are described in this paper. The parameters that determine the device feasible force-velocity region are identified and discussed. The effectiveness of this hybrid damper is evaluated through a numerical simulation study on vibration mitigation of a bridge stay cable under wind excitation. It is demonstrated that the proposed hybrid design outperforms the passive case without external power supply. It is also shown that a broader force range, facilitated by decoupled passive and semi-active modes, can improve the vibration performance of the cable.
Preoperative Bariatric Surgery Predictors of Type 2 Diabetes Remission
Joshua Fultang,Ugochukwu Chinaka,Jean Rankin,Andisheh Bakhshi,Abdulmajid Ali 대한비만학회 2021 The Korean journal of obesity Vol.30 No.2
Obesity represents a significant proportion of the global public health burden, with the World Health Organization (WHO) estimating more than 600 million people are affected worldwide. Unfortunately, the epidemic of obesity is linked to the increased prevalence of associated metabolic diseases such as type 2 diabetes mellitus (T2DM). Bariatric surgery as an intervention has been shown to provide sustainable weight loss, and also leads to superior short- and long-term metabolic benefits including T2DM remission. Despite this added advantage conferred by bariatric surgery, emerging evidence has shown that not all patients with T2DM achieve remission postoperatively. As such, to improve patient selection and optimize preoperative counselling, research has focused on the preoperative predictors of T2DM remission following bariatric surgery. Herein, we provide a critical review of the current literature addressing preoperative predictors of T2DM remission and highlight the current gaps in the literature. The review comprised a multistage advanced electronic search of the Ovid/Medline, Embase, and Cochrane online libraries to identify available studies published over the last decade.