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Sekar Abinaya,Mariappan Saravanakumar,Krishnan Chitra Shankar,Sampathkumar Jayakrishnakumar,Ramakrishnan Hariharan,Mahadevan Vallabh,Sivaprakasam Azhagarasan Nagarasampatti 대한치과이식(임프란트)학회 2022 The Korean Academy of Implant Dentistry Vol.41 No.4
Purpose: This study compared the accuracy of different elastomeric impression materials with open tray implant level impression technique in a single-tooth replacement. Materials and Methods: A reference model representing a single implant with an adjacent simulated natural tooth was fabricated. Open tray implant level impressions were made with vinylpolysiloxane (light body ExpressXT, PentaputtyPentamix2, 3MESPE, Seinfield, Germany) (Group I, n=10) and polyether (medium body Impregnum Penta, Pentamix 2, 3MESPE, Seinfield, Germany), (Group II, n=10) and implant crowns were fabricated on each master cast from their respective impressions by CNC milling and connected to the reference model with 35 Ncm torque. The accuracy of the fit was evaluated by measuring the interface gap between the implant crown and the implant replica at the mesial and distal points and by measuring the proximal gap between the implant crown and the simulated natural tooth at the buccal and the palatal points by scanning electron microscopy for each test sample. The mean values were obtained and statistically analyzed using a Mann-Whitney test. Results: The interface gap observed at the mesial point was significantly higher than the distal point. The proximal gap observed at the palatal point was significantly higher than the buccal point for both Group I and Group II. A comparison of the groups showed that the interface gap at the mesial point and the proximal gap at the buccal and palatal points obtained from polyether impression material were lower than those observed with vinylpolysiloxane group, but the difference was not significant. However, the interface gap observed at the distal point was higher with the polyether group than with the vinylpolysiloxane group, but the difference was not significant. Conclusions: Polyether and vinylpolysiloxane can be used to produce open tray implant impressions for a single missing tooth.
Parametric NURBS Curve Interpolators
Sekar Mohan,Sung-Hwan Kweon,Dong-Mok Lee,Seung-Han Yang 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.2
Free-form shapes which were once considered as an aesthetic feature are now an important functional requirement. CNC industries are looking for a compact solution for reproducing free-form shapes as conventional interpolation models are inadequate. The parametric curve interpolator developed in the last decade has clearly emerged as favorite among its contemporaries in recent years. At present intense research has been done on parametric curve interpolators and interesting developments are reported. Out of the various parametric representations for curves and surfaces, NURBS has been standardized and widely used in free-form shape design. This paper presents a review of various methods of parametric interpolation for NURBS and discusses the salient features, problems and solutions. Recent approaches on variable feedrate interpolation, parameter compensation are also reviewed and research trends are addressed finally.
PANI-Based Wearable Electrochemical Sensor for real time Sweat pH Monitoring
Sekar Madhu(세카르 마두),Md. Sajjad Alam(Md. 사자드 알람),Jungil Choi(최정일) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Sweat pH is an important health indicator related to metabolism and homeostasis level over hydrogen ion concentration in biological bio-fluid. Therefore, increasing research efforts have been motivated to develop wearable pH sensors towards continuous non-invasive monitoring of sweat pH values. A textile based skin-mounted microfluidic potentiometric device for electrochemical monitoring of pH in sweat is presented. The fabricated Polyaniline (PANI) incorporated carbon cloth (CC) pH sensor was tested in the range from 4 to 7, showing good behavior, with a sensitivity of 64.4 mV/pH, very close to a Nernstian response, better repeatability and good ion selectivity. Finally, a real sweat sample was collected, and the sweat pH was quantified with both the proposed sensor and a commercial pH meter, showing an excellent concordance. This soft skin-worn platform integrates potentiometric measurement, microfluidic technologies with flexible electronics for real-time wireless data transmission to mobile devices. The proposed device paves the way to build a novel practical fitness and health monitoring systems for improving practical fitness of human in real-time.
Multi-Parameter Approach for Evaluation of Genomic Instability in the Polycystic Ovary Syndrome
Sekar, Nishu,Nair, Manju,Francis, Glory,Kongath, Parvathy Raj,Babu, Sandhya,Raja, Sudhakaran,Gopalakrishnan, Abilash Valsala Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16
Background: The polycystic ovary syndrome (PCOS), characterized by hyperandrogenism and chronic anovulation, is a common endocrine disorder in women. PCOS, which is associated with polycystic ovaries, hirsutism, obesity and insulin resistance, is a leading cause of female infertility. In this condition there is an imbalance in female sex hormones. All the sequelae symptoms of PCOS gradually lead to cancer in the course of time. It is heterogeneous disorder of unknown etiology so it is essential to find the exact cause. Materials and Methods: In this study both invasive and non-invasive techniques were employed to establish the etiology. Diagnosis was based on Rotterdam criteria (hyperandrogenism, ovulatory dysfunction, PCOM) and multiparameters using buccal samples and dermatoglypic analysis and cytogenetic study for 10 cases and four age and sex matched controls. Results: In clinical analysis we have observed the mean value of total testosterone level was 23.6nmol/L, total hirsutism score was from 12-24, facial acne was found in in 70% patients with 7-12 subcapsular follicular cysts, each measuring 2-8 mm in diameter. In dermatoglypic analysis we observed increases in mean value ($45.9^{\circ}$) of ATD angle when compared with control group and also found increased frequency (38%) of Ulnar loops on both fingers (UU), (18%) whorls on the right finger and Ulnar loop on left finger (WU) and (16%) arches on right and left fingers (AA) were observed in PCOS patients when compared with control subjects. Features which could be applied as markers for PCOS patients are the presence of Ulnar loops in middle and little fingers of right and left hand. The buccal micronucleus cytome assay in exfoliated buccal cells, we found decrease in frequency of micronuclei and significant increases in frequency of karyolysed nuclei in polycystic ovarian syndrome patients. Chromosome aberration analysis revealed a significant increase in frequency of chromosome aberrations (CAs) in PCOS patients when compared with controls. Conclusions: From this present work it can be concluded that non-invasive technique like dermatoglypics analysis and buccal micronucleus cytome assays with exfoliated buccal cell can also be effective biomarkers for PCOS, along with increased CAs in lymphocytes as a sign of genetic instability. There is a hypothesis that micronuclei and chromosomal aberrations could have a predictive value for cancer. From this present work it can be concluded to some extent that non-invasive technique like dermatoglypics and buccal cell analysis can also be effective for diagnosis.
Growth and Characterization of GaN on Sapphire and Porous SWCNT Using Single Molecular Precursor
Sekar, P.V. Chandra,Lim, Hyun-Chul,Kim, Chang-Gyoun,Kim, Do-Jin Materials Research Society of Korea 2011 한국재료학회지 Vol.21 No.5
Due to their novel properties, GaN based semiconductors and their nanostructures are promising components in a wide range of nanoscale device applications. In this work, the gallium nitride is deposited on c-axis oriented sapphire and porous SWCNT substrates by molecular beam epitaxy using a novel single source precursor of $Me_2Ga(N_3)NH_2C(CH_3)_3$ with ammonia as an additional source of nitrogen. The advantage of using a single molecular precursor is possible deposition at low substrate temperature with good crystal quality. The deposition is carried out in a substrate temperature range of 600-750$^{\circ}C$. The microstructural, structural, and optical properties of the samples were analyzed by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and photoluminescence. The results show that substrate oriented columnar-like morphology is obtained on the sapphire substrate while sword-like GaN nanorods are obtained on porous SWCNT substrates with rough facets. The crystallinity and surface morphology of the deposited GaN were influenced significantly by deposition temperature and the nature of the substrate used. The growth mechanism of GaN on sapphire as well as porous SWCNT substrates is discussed briefly.