Accuracy of Thoracolumbar Pedicle Screw Insertion Based on Routine Use of Intraoperative Imaging and Navigation

Sundaram Pirateb Paramasivam Meenakshi,Oh Jacob Yoong-Leong,Tan Mark,Nolan Colum Patrick,Yu Chun Sing,Ling Ji Min 대한척추외과학회 2021 Asian Spine Journal Vol.15 No.4

Study DesignRetrospective review.PurposeTo determine the accuracy of thoracolumbar pedicle screw insertion with the routine use of three-dimensional (3D) intraoperative imaging and navigation over a large series of screws in an Asian population.Overview of LiteratureThe use of 3D intraoperative imaging and navigation in spinal surgery is aimed at improving the accuracy of pedicle screw insertion. This study analyzed 2,240 pedicle screws inserted with the routine use of intraoperative navigation. It is one of very few studies done on an Asian population with a large series of screws.MethodsPatients who had undergone thoracolumbar pedicle screws insertion using intraoperative imaging and navigation between 2009 and 2017 were retrospectively analyzed. Computed tomography (CT) images acquired after the insertion of pedicle screws were analyzed for breach of the pedicle wall. The pedicle screw breaches were graded according to the Gertzbein classification. The breach rate and revision rate were subsequently calculated.ResultsA total of 2,240 thoracolumbar pedicle screws inserted under the guidance of intraoperative navigation were analyzed, and the accuracy of the insertion was 97.41%. The overall breach rate was 2.59%, the major breach rate was 0.94%, and the intraoperative screw revision rate was 0.7%. There was no incidence of return to the operating theater for revision of screws.ConclusionsThe routine use of 3D navigation and intraoperative CT imaging resulted in consistently accurate pedicle screw placement. This improved the safety of spinal instrumentation and helped in avoiding revision surgery for malpositioned screws.

Polydopamine layered poly (ether imide) ultrafiltration membranes tailored with silver nanoparticles designed for better permeability, selectivity and antifouling

Meenakshi Sundaram Sri Abirami Saraswathi,Dipak Rana,Subbiah Alwarappan,Shanmugaraj Gowrishankar,Prabu Vijayakumar,Alagumalai Nagendran 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.76 No.-

Poly (ether imide) [PEI] ultrafiltration membranes are coated by polydopamine (PD) and immobilizedwith silver nanoparticles (AgNPs) to improve the permeation, contaminant separation and anti-foulingproperties. The tailored membranes displayed enhanced permeability (97.2 Lm 2 h 1), hydraulicresistance (13.8 kPa/Lm 2 h 1), average roughness (43 nm), contaminant rejection (>97%) with a higherflux recovery ratio (>95%). PEI/PD/Ag membranes showed anti-biofouling property against gramnegative and gram positive bacteria and facilitated the separation of toxic contaminants. The outstandingstability of PD coating and the presence of AgNPs offer effective and safe water separation.

Combination of Novel Converter Topology and Improved MPPT Algorithm for Harnessing Maximum Power from Grid Connected Solar PV Systems

B. Meenakshi Sundaram,B. V. Manikandan,B. Praveen Kumar,D. Prince Winston 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.2

It is a diffi cult task to utilize the power from the solar PV connected to utility grid eff ectively due to its lower effi ciency. Hence, a new power electronic topology with maximum power point tracking (MPPT) algorithm is needed to reduce the losses thereby obtaining the maximum power from solar PV system. Direct energy transfer is implemented to transfer the rated solar power to the utility grid, the rest is fed to the converter and used for DC loads. In this work, a reversed buck-boost converter topology with parallel power processing concept is used effi ciently and a multiple perturbation and observation (MP&O) based MPPT algorithm is proposed to achieve the global maximum power point (GMPP). And also boost inverter topology is employed by which the power from PV is supplied to the utility grid. The proposed method is simulated using MATLAB/SIMULINK and implemented in hardware. The simulation and experimental results of the proposed MP&O technique provide maximum AC power as well as DC power even in low irradiance and partial shading conditions of the solar PV array compared to the existing techniques.

Enhanced Controller Topology for Photovoltaic Sourced Grid Connected Inverters under Unbalanced Nonlinear Loading

P. Sivakumar,Meenakshi Sundaram Arutchelvi 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2

A growing dynamic electrical demand has created an increasing interest in utilizing nonconventional energy sources like Photovoltaic (PV), wind power, etc. In this context, this paper focuses on the design and development of a composite power controller (CPC) in the decoupled double synchronous reference frame (DDSRF) combining the advantages of direct power control (DPC) and voltage oriented control (VOC) for a PV sourced grid connected inverter. In addition, a controller with the inherent active filter configuration is tested with nonlinear and unbalanced loads at the point of common coupling in both grid connected and autonomous modes of operation. Furthermore, the loss and reactive power compensation due to a non-fundamental component is also incorporated in the design, and the developed DDSRF model subsequently allows independent active and reactive power control. The proposed developed model of the controller is also implemented using MATLAB-Simulink-ISE and a Xilinx system generator which evaluate both the simulated and experimental setups. The simulation and experimental results confirm the validity of the developed model. Further, simulation results for the DPC are also presented and compared with the proposed CPC to further bring out the salient features of the proposed work.

Evaluation of Antitumor and Antioxidant Activity of Sargassum tenerrimum against Ehrlich Ascites Carcinoma in Mice

Patra, Satyajit,Muthuraman, Meenakshi Sundaram,Prabhu, A.T.J. Ram,Priyadharshini, R. Ramya,Parthiban, Sujitha Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.3

Context: In the last half century, discovering, developing and introducing of clinical agents from marine sources have seen great successes, with examples including the anti-cancer compound trabectedin. However, with increasing need for new anticancer drugs, further exploration for novel compounds from marine organism sources is strongly justified. Objective: The major aim of this study was to evaluate the antitumor and antioxidant potential of Sargassum tenerrimum J.Agardh (Sargassaceae) on Ehrlich ascites carcinoma (EAC) in Swiss albino mice. Materials and Methods: An ethanol extract of S. tenerrimum (EEST) from whole algae was used to evaluate cytotoxicity followed by in vivo assessment of toxicity, using biochemical parameters including hepatic and non-hepatic enzymes. Antioxidant properties were examined in animals bearing EAC treated with daily oral administration of 100-300 mg/kg extract suspension. Results: Antitumor effects of EEST in EAC bearing mice was observed with LD50 1815 mg/kg. Parameters like body weight, tumor volume, packed cell volume, tumor cell count, mean survival time and increase in life span in animals in the EAC bearing animals treated with EEST 300 mg/kg was comparable with control group. Significant differences were also seen with changes in total protein content, hepatic enzymes contents, MDA level, and free radical scavenging enzymes in untreated vs. EEST treated group animals. Conclusions: Evaluation of antioxidant enzymes and hepatic enzymes in the EAC animal model treated with EEST exhibited similar effects as the positive control drug 5-flurouracil. S. tenerrimum extracts contain effective antioxidants with significant antitumor activity.

Enhanced Controller Topology for Photovoltaic Sourced Grid Connected Inverters under Unbalanced Nonlinear Loading

Sivakumar, P.,Arutchelvi, Meenakshi Sundaram The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2

A growing dynamic electrical demand has created an increasing interest in utilizing nonconventional energy sources like Photovoltaic (PV), wind power, etc. In this context, this paper focuses on the design and development of a composite power controller (CPC) in the decoupled double synchronous reference frame (DDSRF) combining the advantages of direct power control (DPC) and voltage oriented control (VOC) for a PV sourced grid connected inverter. In addition, a controller with the inherent active filter configuration is tested with nonlinear and unbalanced loads at the point of common coupling in both grid connected and autonomous modes of operation. Furthermore, the loss and reactive power compensation due to a non-fundamental component is also incorporated in the design, and the developed DDSRF model subsequently allows independent active and reactive power control. The proposed developed model of the controller is also implemented using MATLAB-Simulink-ISE and a Xilinx system generator which evaluate both the simulated and experimental setups. The simulation and experimental results confirm the validity of the developed model. Further, simulation results for the DPC are also presented and compared with the proposed CPC to further bring out the salient features of the proposed work.

Global Inactivation of the Pla2g6 Gene in Mice Does Not Cause Dyslipidemia under Chow or High-fat Diet Conditions

Li Zhang,Shumei Zhong,Ying Li,Guang Ji,Meenakshi Sundaram,Zemin Yao 대한암예방학회 2013 Journal of cancer prevention Vol.18 No.3

Background: Genome-wide association studies suggest that plasma triacylglyceride (TAG) in humans was associated with variation in the PLA2G6 locus, a gene that encodes calcium-independent phospholipase A2 (iPLA2Ղ). The objective of the present study is to understand the impact of genetic inactivation of iPLA2Ղ on hepatic TAG metabolism in C57BL/6 mice.Methods: Male iPLA2Ղ+/− mice were backcrossed with female iPLA2Ղ−/− mice for up to 10 generations prior to experiments. Lipid and lipoprotein metabolism from plasma, hepatocytes, thigh subcutaneous adipose and thigh skeletal muscle tissues of the mice were determined under various experimental conditions.Results: The iPLA2Ղ−/− mice, either male or female as compared with iPLA2Ղ+/+ littermates, showed no change in fasted or postprandial plasma TAG or total cholesterol at young (12-15 weeks) or old (40-44 weeks) ages under chow diet or high-fat diet (HFD) conditions. However, fractionation of plasma lipoproteins showed that under HFD conditions, there was a significant increase (by 40%) in apoB-100 association with VLDL1 fractions in iPLA2Ղ−/− mice as compared with iPLA2Ղ+/+ littermates. There was no significant difference in triglyceride or cholesterol contents in the liver, muscle, or adipose tissue between iPLA2Ղ−/− and iPLA2Ղ+/+ littermates. Metabolic labeling experiments with cultured primary hepatocytes isolated from iPLA2Ղ−/− mice also showed 2-fold increase in the secretion of [35S]methionine-labeled apoB-100 in VLDL1 fractions as compared with that from iPLA2Ղ+/+hepatocytes. Likewise, secretion of [3H]palmitate-labeled TAG from the iPLA2Ղ−/− hepatocytes was increased by 2-fold.Conclusions: Although iPLA2Ղ may play a role in TAG-rich VLDL1 production from cultured hepatocytes, there is no evidence that inactivation of iPLA2Ղ would lead to dyslipidemia in mice in vivo.