Thoracic and Lumbar Pedicle Morphometry in Achondroplasia

Kumar, C Palani,Song, Hae-Ryong,Lee, Seok-Hyun,Suh, Seung-Woo,Oh, Chang-Wug Lippincott WilliamsWilkins, Inc. 2007 Clinical orthopaedics and related research Vol.454 No.-

For safe pedicle screw insertion, knowing pedicle anatomy is essential. Pedicle morphometry in achondroplasia has not been quantitatively described. Therefore, we analyzed 302 thoracic and lumbar pedicles in 11 patients using computed tomography. Transverse endosteal diameter, screw path length, transverse angle, sagittal diameter, and sagittal angle were calculated. We analyzed for safe screw length, size, and trajectory. The data were compared with that on healthy people of different races. In patients with achondroplasia, the maximum endosteal diameter was at L5 and the minimum was at T5. Screw path length was longest at L2 and shortest at T2. Most dimensions were smaller compared with those of healthy people. Abnormal anteromedial transverse angulations were observed between T11 to L2. The maximum transverse angulations were at T2. Sagittal diameter was largest at T12 and smallest at T5. The maximum sagittal angle was seen at T2, and at L5 it was caudal. At all levels except L5, the transverse diameter is the limiting factor for screw size. Six-millimeter screws can be used at L5. Screws that are 35 mm or less are safe to use between T7 to L5. There are surgically important differences in the different angles and diameters of thoracic and lumbar pedicles of patients with achondroplasia and those of healthy people.Level of Evidence: Level IV, diagnostic study (case control study). See the Guidelines for Authors for a complete description of levels of evidence.

Theoretical and Computational Analysis of LNG Evaporator

Palani Kumar Chidambaram,Seok Woo Son,Heuy Dong Kim(김희동),Dong Wook Kim(김동욱),Yang Myung Jo(조양명) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12

Theoretical and numerical predictions on fluid flow and heat transfer in a typical LNG evaporator is performed. Methane is used in lieu of LNG as it constitutes over 80% of LNG. The theoretical predictions are performed by simple energy balance between the steam and methane. This is augmented by the mass transfer between the liquid phase methane and gas phase methane. The theoretical predictions are made to calculate the pressure drop and temperature drop in the steam tubes. Numerical simulations are carried out by solving the governing equations of multiphase flow in a portion of the evaporator domain with a single layer of steam pipe. The basic flow equations of continuity, momentum and energy equations form the governing equations along with equations of species transport. Multiphase modelling is incorporated using VOF method. Liquid methane is taken as primary phase. It vaporizes into gaseous methane which is taken to be secondary phase. Steam is taken as another secondary phase which flows through the heating coils. Closure for turbulence is modelled by a two equation turbulence model. Both the analytical and numerical predictions match well with each other. Further parametric studies are planned based on the current research.

Investigations on the Performance Characteristics of Carbon Nano-tubes, Alumina and Titanium Dioxide Based Plasma Sprayed Coatings on AISI 1020 Steel

Vijayanand Palani,Amitesh Kumar,K. R. Vijaya Kumar,P. Kumaran 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.2

The current study deals with the investigation on the performance characteristics of varying composition of coating mixture comprising carbon nano-tube, alumina and titanium dioxide on the thermal spray coating on mild steel. The performance properties, namely tensile and microhardness, were measured for the varying composition of coating mixture based thermal coating on mild steel. Response surface methodology was adopted to access the interdependencies prevailing between various dependent and independent parameters, namely composition of the mixture, tensile and microhardness. Scanning Electron Microscope coupled with elemental mapping were used to show the melting zones features and composition. The experimental results and response graphs indicated that increased weight percentages of carbon nano-tube and TiO2 with an optimal value of alumina at 87.5 percent of total weight showed better performance properties due to better dispersion leading to good bonding suitable for protective coatings. Scanning Electron Microscope images reveal partially melted zones that were restricted to smaller regions, and all particles tend to solidify beginning with a fully molten phase.

A Computational Study on the Scale Effects of Hybrid Rocket Motors

C Palani Kumar,Amit Kumar,Heuy-Dong Kim(김희동) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

In the present work, a numerical investigation is carried out for physics based identification of key parameters that govern scaling of single cylindrical port hybrid rocket motors. The grain port length to port diameter (or L/D) ratio was found to be a key scaling parameter along with maintaining oxidizer mass flux (GOX) for near identical motor performance. Since L/D ratio dictates the overall oxidizer to fuel ratio (O/F), there exists an optimal L/D ratio (near stoichiometric overall O/F ratio) at which the characteristic exhaust velocity C<SUP>*</SUP> and combustion efficiency ηC are maximum. Thus the scope for tangible improvement in C<SUP>*</SUP> and ηC using a regression rate enhancement technique is only for motors with grain L/D ratio appreciably less than the optimal L/D ratio.

Optimization study on pin tip diameter of an impact-pin nozzle at high pressure ratio

C. Palani Kumar,Kwon Hee Lee,Tae Choon Park,Bong-Jun Cha,Heuy Dong Kim 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.9

Wet compression system is typically installed in a gas turbine engine to increase the net power output and efficiency. A crucial component of the wet compression system is the nozzle which generates fine water droplets for injection into the compressor. The main objective of present work is to optimize a kind of nozzle called impact-pin spray nozzle and thereby produce better quality droplets. To achieve this, the dynamics occurring in the water jet impinging on the pin tip, the subsequent formation of water sheet, which finally breaks into water droplets, must be studied. In this manuscript, the progress on the numerical studies on impact-pin nozzle are reported. A small computational domain covering the orifice, pin tip and the region where primary atomization occurs is selected for numerical analysis. The governing equations are selected in three dimensional cartesian form and simulations are performed to predict the dynamics of water jet impinging on the pin. Systematic studies were carried out and the results leading to the choice of turbulence model and the effect of pin tip diameter are reported here. Further studies are proposed to show the future directions of the present research work.

Hepatoprotective and antioxidant effects of Monochoria vaginalis against acetaminophen-induced hepatotoxicity in rats

Palani, S.,Raja, S.,Sakthivel, K.,Devi, K.,Kumar, B. Senthil Kyung Hee Oriental Medicine Research Center 2010 Oriental pharmacy and experimental medicine Vol.10 No.1

The present study was aimed to investigate the hepatoprotective and antioxidant activities of ethanol extract from Monochoria vaginalis (250 mg/kg and 500 mg/kg B/W) on acetaminophen (APAP) induced rat hepatic injury. Monochoria vaginalis is a traditional medicinal plant that is commonly used to treat and improve liver conditions in India and other Asian countries. The development of hepatotoxicity induced by APAP is promoted by oxidative stress. APAP treated group significantly (P < 0.01) elevated the serum enzymatic levels like glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, alkaline phosphatase (SALP), total bilirubin and malondialdehyde (MDA), which were restored towards normalization significantly (P < 0.01) thanol extract of yonochoria vagin is (EEMV). In addition, the EEMV significantly (P < 0.01) elevated the decreased level of total protein and antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione-s-transferase and reduced glutathione. Apart from these, histopathological changes also showed the protective nature of the EEMV against APAP induced hepatic damage in liver tissues. The activity of EEMV at 500 mg/kg B/W was comparable to the standard drug silymarin (25 mg/kg B/W). In conclusion, these data suggest that the EEMV possess hepatoprotective and antioxidant effects against APAP-induced hepatotoxicity and oxidative stress in rats.

Alternating and Merged Droplets in a Double T-junction Microchannel

Harish Palani Naga Surya,Sajeesh Parayil,Utsab Banerjee,Subhash Chander,Ashis Kumar Sen 한국바이오칩학회 2015 BioChip Journal Vol.9 No.1

In this work, we report experimental andnumerical studies of alternating and merged dropletsin a double T-junction microchannel. The microchanneldevice is fabricated using PDMS substrate and experimentsare performed with mineral oil with surfactantas the continuous phase and aqueous glycerol asthe discrete phase. Based on the flow rate fraction φand Capillary number Ca, four different flow regimesare identified: merging, stable alternating droplets, alternatingdroplets with transition and laminar. A numericalmodel that employs volume-of-fluid formulationsis used to predict the alternating droplet generationprocess. In the stable alternating droplet regime,the effect of the discrete phase flow rate ratio α on thedroplet diameter ratio β is experimentally studied andcompared with that predicted from the simulations. Itis observed that the droplet diameter ratio β increaseslinearly with increase in the flow rate ratio α and agood match between experiments and simulations isobserved. The diameters of droplets at different Capillarynumbers Ca generated using single and doubleT-junction microchannels are compared and it is observedthat, at low Ca, the double T-junction generateslarger droplets as compared to single T-junction. In merged droplet regime, the effect of the continuousphase flow rate Qc and discrete phase viscosity μd ondiameter dm and interdistance between the droplets λof the merged droplets are studied. It is observed thatthe merged droplet diameter dm is reduced and interdistancebetween the droplets λ increases with increasein the continuous phase flow rate Qc. As the viscosityof the discrete phase μd increases, the diameter dm andinterdistance between the droplets λ of the mergeddroplets decreases.

Hepatoprotective and antioxidant effects of Monochoria vaginalis against acetaminophen-induced hepatotoxicity in rats

S Palani,S Raja,K Sakthivel,K Devi,B Senthil Kumar 경희대학교 융합한의과학연구소 2010 Oriental Pharmacy and Experimental Medicine Vol.10 No.1

The present study was aimed to investigate the hepatoprotective and antioxidant activities of ethanol extract from Monochoria vaginalis (250 mg/kg and 500 mg/kg B/W) on acetaminophen (APAP)induced rat hepatic injury. Monochoria vaginalis is a traditional medicinal plant that is commonly used to treat and improve liver conditions in India and other Asian countries. The development of hepatotoxicity induced by APAP is promoted by oxidative stress. APAP treated group significantly (P < 0.01) elevated the serum enzymatic levels like glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, alkaline phosphatase (SALP), total bilirubin and malondialdehyde (MDA), which were restored towards normalization significantly (P < 0.01)thanol extract of yonochoria vagin is (EEMV). In addition, the EEMV significantly (P < 0.01)elevated the decreased level of total protein and antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione-s-transferase and reduced glutathione. Apart from these, histopathological changes also showed the protective nature of the EEMV against APAP induced hepatic damage in liver tissues. The activity of EEMV at 500 mg/kg B/W was comparable to the standard drug silymarin (25 mg/kg B/W). In conclusion, these data suggest that the EEMV possess hepatoprotective and antioxidant effects against APAP-induced hepatotoxicity and oxidative stress in rats.

Thermo-fluid dynamic analysis of wet compression process

Abhay Mohan,Palani Kumar Chidambaram,Abhilash Suryan,Heuy Dong Kim 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.12

Wet compression systems increase the useful power output of a gas turbine by reducing the compressor work through the reduction of air temperature inside the compressor. The actual wet compression process differs from the conventional single phase compression process due to the presence of latent heat component being absorbed by the evaporating water droplets. Thus the wet compression process cannot be assumed isentropic. In the current investigation, the gas-liquid two phase has been modeled as air containing dispersed water droplets inside a simple cylinder-piston system. The piston moves in the axial direction inside the cylinder to achieve wet compression. Effects on the thermodynamic properties such as temperature, pressure and relative humidity are investigated in detail for different parameters such as compression speeds and overspray. An analytical model is derived and the requisite thermodynamic curves are generated. The deviations of generated thermodynamic curves from the dry isentropic curves (PV γ = constant) are analyzed.

A Fundamental Study on Droplet Evaporation in Wet Compression Systems

Abhay Mohan,Palani Kumar Chidambaram,Abhilash Suryan,Heuy Dong Kim(김희동) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

For the current investigation, the gas liquid two-phase media are modeled as air involving fine droplet or droplets of water. A cylinder-piston system is modeled which contains air with single or multiple droplets of water. The compression process is achieved by the movement of the piston. During the compression process, thermodynamic properties such as temperature and pressure are investigated in detail. Analytical equations have been derived to obtain the transformation in fluid properties. The results thus obtained are discussed for different conditions of overspray and initial absolute humidity of the air inside the cylinder. The thermodynamic curves obtained are seen to deviate significantly from the dry isentropic curve ( PVγ=constant) with decreasing droplet diameters and increasing mass of droplets. This deviation can be associated with the latent heat absorbed by the evaporating droplets during the process of compression.