Evaluation of the effects of oral rinses on the retention and surface topography of the ball attachment complex for implant overdentures

Dhanapriya Gopalakrishnan(Dhanapriya Gopalakrishnan ),Azhagarasan Nagarasampatti Sivaprakasam(Azhagarasan Nagarasampatti Sivaprakasam ),Vidhya Jeyapalan(Vidhya Jeyapalan ),Jayakrishnakumar Sampathkuma 대한치과이식임플란트학회 2023 The Korean Academy of Implant Dentistry Vol.42 No.1

Purpose: To evaluate the effect of two different oral rinses on the retention and surface topography of ball attachments for implant overdentures. Materials and Methods: Thirty metal housing and the nylon cap inserts (Adin, Israel) were placed on the master block and the attachment assemblies were transferred to prosthetic blocks using the direct pickup technique. Group I had ten test samples immersed in water, Group II had ten test samples immersed in Listerine® Cool Mint®(J&J, India), Group III had ten test samples immersed in Colgate Vedshakthi oil-based herbal oral rinse (Colgate-Palmolive, India). The retention force was tested at baseline and after immersion in the respective oral rinses at 360 cycles (simulating 3 months) and 720 cycles (simulating 6 months) of clinical use, using a universal testing machine (Shimadzu, AG-X plus 50KN, Europe, GmBH) at a crosshead speed of 50 mm/min. The data was analyzed using the repeated measures ANOVA test, one-way ANOVA test, and post hoc analysis (SPSS23, Munich, Germany). The surface topography was assessed initially and subsequently after immersion in the oral rinses after 360 and 720 insertion-removal cycles using a stereomicroscope (Leica M205C, Germany). Results: At 360 cycles, the mean retention force (MRF) exhibited by Group I was higher than that of Group III and this difference was significant. The MRF of Group II was also significantly higher than Group III. At 720 cycles, the MRF exhibited by Group I was higher than that of Group II and the difference was significant. Also, the MRF of Group I was significantly higher than that of Group III, and the MRF of Group II was significantly higher than that of the Group III test samples. In Group I, the percentage loss in the MRF at the end of 360 and 720 cycles was 4.96% and 6.37%, respectively. In Group II, it was 6.82% and 9.41%, respectively, and in Group III it was 14.75% and. 16.60%, respectively. Conclusions: Colgate Vedshakti caused the highest surface topographic changes. This corroborates with the lower retention obtained, followed by Listerine® Cool Mint®, and the least changes were observed for samples immersed in water, which corroborates with the greater retention obtained in the study.

A Convenient One-Pot Biginelli Reaction Catalyzed by Y(OAc)3: An Improved Protocol for the Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Their Sulfur Analogues

Gopalakrishnan Aridoss,Yeon Tae Jeong 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.4

Yttrium(III) acetate hydrate-catalyzed novel synthesis of 3,4-dihydropyrimidin-2(1H)-(thio)one derivatives was achieved through one-pot three-component condensation of diversified aldehydes, β-ketoesters and urea or N-methylurea or thiourea with a molar ratio of 1:1:1.4. In comparison to the classical Biginelli approach, this catalytic method has the advantages of short reaction time and improved product yield.

Modified Chilled Coil Model Development and Application to Turbine Inlet Air Cooling

Gopalakrishnan Anand,Ellen Makar 대한설비공학회 2021 International Journal Of Air-Conditioning and Refr Vol.29 No.1

A Turbine Inlet Air Conditioning (TIAC) system can chill the inlet air of the turbine to maintain maximum turbine performance at all ambient temperatures. However, turbine characteristics, performance guarantees and bell-mouth icing considerations require accurate prediction of the chilling coil performance over a wide range of operating conditions. A modified wet-surface model (MWSM) is developed to more accurately predict the chilling coil performance. The higher accuracy of the model is demonstrated by applying the model to simulate performance data of two different coils. The data covered a wide range of operating conditions with ambient temperature vary from 43.3∘C to 9.7 ∘ C dry bulb and 27.2 ∘C to 6.1 ∘C wet bulb. The turbine flow rate varies from 100% to 43% with chilled air temperature in the range of 3.3–14 ∘ C and chilling load variation of 100% to 5%. The chilled water flow rate varies from 100% to 32% with supply glycol-water temperature in the range of −2.2–6.1 ∘ C. The MWSM uses 11 empirical parameters evaluated from the coil performance data and is able to correlate the data with an adjusted coefficient of determination (R 2 adjRadj2) of over 99%. The higher accuracy of the modified model enables the development of a more robust controls strategy required to maintain the inlet air temperature at the set point with varying ambient temperatures and chilling load conditions. The model can also be applied to other chilling and dehumidification applications especially those experiencing wide variations in operating conditions and load or those requiring close control of the chilling and dehumidification process.

Chilled Coil Control and Field Performance for Turbine Inlet Air Chilling

Gopalakrishnan Anand,Ellen Makar 대한설비공학회 2021 International Journal Of Air-Conditioning and Refr Vol.29 No.2

Ambient conditions greatly affect the combustion turbine performance. The Absorption Refrigeration Cycle Turbine Inlet Chilling (ARCTIC) system can chill the inlet air of the turbine to maintain optimum performance at all ambient temperatures. However, turbine characteristics, bell-mouth icing concerns, economics and performance guarantees require maintaining the inlet air temperature within a narrow range throughout the year. These considerations require strict control of the Turbine Inlet Air Chilling (TIAC) coil performance over a wide range of operating conditions. This paper describes the field performance and control of the chilling coil for a Mars 100 turbine. The controls logic had been developed from previously published empirical model of the chilling coil and model of the chilling loop performance at the various ambient conditions. Since commissioning at the end of summer 2020, the ARCTIC has provided inlet air chilling over a range of ambient conditions. Typically, the inlet air is maintained at 7.2∘C (45∘F) by controlling the TIAC chilled water flow rate and temperature. On cooler days, if the inlet air temperature drops to 5.6∘C (42∘F) the chilled water pump turns OFF automatically to prevent bell-mouth icing. Thus, the chiller accommodates chilling load variations down to zero load. On colder days, the ARCTIC continues operating till the ambient temperature drops below 1.7∘C (35∘F) and then turns OFF. The chiller turns back ON when the 8 h average inlet air temperature exceeds 10∘C (50∘F). These parameters can be adjusted remotely by the operator and help maintain performance guarantees while minimizing chiller cycling. Quasi-steady state data were analyzed to quantify the chilling load and coil performance over a range of operating conditions.

Isolation, Purification, and Characterization of Haloalkaline Xylanase from a Marine Bacillus pumilus Strain, GESF-1

Gopalakrishnan Menon,Kalpana Mody,Jitendra Keshri 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.6

A haloalkalitolerant xylanase-producing Bacillus pumilus strain, GESF1 was isolated from an experimental salt farm of CSMCRI. Birch wood xylan and xylose induced maximum xylanase production with considerable activity seen in wheat straw and no activity at all with caboxymethyl cellulose (CMC). A three step purification yielded 21.21-fold purification with a specific activity of 112.42 U/mg protein (unit expressed as μmole of xylose released per min). Xylanase produced showed an optimum activity at pH 8.0, with approximately 50 and 30% relative activity at a pH 6.0 and 10.0, respectively. The temperature optimum was 40°C and kinetic properties such as Km and Vmax were 5.3 mg/mL and 0.42 μmol/min/mL (6593.4μmol/min/mg protein). Xylanase activity (160 ~ 120%)was considerably enhanced in 2.5 to 7.5% NaCl with 87and 73% retention of activity in 10 and 15% of NaCl. Enzyme activity was enhanced by Ca2+, Mn2+, Mg2+, and Na+ but strongly inhibited by heavy metals such as Hg2+,Fe3+, Cu2+, Cd2+, and Zn2+. Organic reagents such as β-Mercaptoethanol enhanced xylanase activity whereas EDTA strongly inhibited its activity. Xylanase, purified from the Bacillus pumilus strain, GESF1 could have potential biotechnological applications.

Effect of Marsilea quadrifolia (L.) on carbohydrate metabolic enzymes in alloxan induced diabetic rats

Gopalakrishnan Karikalan,Udayakumar Rajangam 한국약제학회 2018 Journal of Pharmaceutical Investigation Vol.48 No.4

Marsilea quadrifolia is an indigenous medicinal plant and it has a folk reputation in central and southern India as hypoglycemic agent. The present study was aimed to evaluate the effect of methanolic leaf and stem extracts of Marsilea quadrifolia on carbohydrate metabolic enzymes in alloxan induced diabetic rats. In this study, the blood glucose level was increased in alloxan induced diabetic rats when compared to normal control rats. The decreased level of blood glucose was observed in diabetic rats treated with leaf and stem of M. quadrifolia. The activities of hexokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphatase, fructose 1,6-bisphosphatase and glucose-6-phosphate dehydrogenase in liver and kidney and glycogen content, glycogen synthase and glycogen phosphorylase in liver were analysed. Glibenclamide was used as a reference drug in the present investigation. The activities of hexokinase, pyruvate kinase and glucose- 6-phosphate dehydrogenase were significantly decreased and the activities of lactate dehydrogenase, glucose-6-phosphatase and fructose 1,6-bisphosphatase were significantly increased in liver and kidney of alloxan induced diabetic rats when compared to normal control rats. Oral administration of methanolic leaf and stem extracts of M. quadrifolia (300 mg/kg bw) to diabetic rats for 45 days showed significantly reverted levels of above mentioned enzymes. The levels of glycogen and glycogen synthase in liver were significantly decreased and the glycogen phosphorylase activity was significantly increased in diabetic rats when compared to normal control rats. The diabetic rats treated with leaf and stem extracts of M. quadrifolia reverted the levels of glycogen, glycogen synthase and glycogen phosphorylase to near normal. The present study clearly indicates that the methanolic leaf and stem extracts of M. quadrifolia possesses potent antidiabetic activity.

Cell Cycle and Mismatch Repair Genes as Potential Biomarkers in Arabidopsis thaliana Seedlings Exposed to Silver Nanoparticles

Gopalakrishnan Nair, Prakash M.,Chung, Ill-Min Springer-Verlag 2014 Bulletin of environmental contamination and toxico Vol.92 No.6

Modulation of Activator Protein-1 (AP-1) and MAPK Pathway by Flavonoids in Human Prostate Cancer PC3 Cells

Gopalakrishnan, Avanthika,Xu, Chang-Jiang,Nair, Sujit S.,Chen, Chi,Hebbar, Vidya,Kong, Ah-Ng Tony The Pharmaceutical Society of Korea 2006 Archives of Pharmacal Research Vol.29 No.8

In last couple of decades the use of natural compounds like flavonoids as chemopreventive agents has gained much attention. Our current study focuses on identifying chemopreventive flavonoids and their mechanism of action on human prostate cancer cells. Human prostate cancer cells (PC3), stably transfected with activator protein 1 (AP-1) luciferase reporter gene were treated with four main classes of flavonoids namely flavonols, flavones, flavonones, and isoflavones. The maximum AP-1 luciferase induction of about 3 fold over control was observed with $20\;{\mu}M$ concentrations of quercetin, chrysin and genistein and $50\;{\mu}M$ concentration of kaempferol. At higher concentrations, most of the flavonoids demonstrated inhibition of AP-1 activity. The MTS assay for cell viability at 24 h showed that even at a very high concentration $(500\;{\mu}M)$, cell death was minimal for most of the flavonoids. To determine the role of MAPK pathway in the induction of AP-1 by flavonoids, Western blot of phospho MAPK proteins was performed. Four out of the eight flavonoids namely kaempferol, apigenin, genistein and naringenin were used for the Western Blot analysis. Induction of phospho-JNK and phospho-ERK activity was observed after two hour incubation of PC3-AP1 cells with flavonoids. However no induction of phospho-p38 activity was observed. Furthermore, pretreating the cells with specific inhibitors of JNK reduced the AP-1 luciferase activity that was induced by genistein while pretreatment with MEK inhibitor reduced the AP-1 luciferase activity induced by kaempferol. The pharmacological inhibitors did not affect the AP-1 luciferase activity induced by apigenin and naringenin. These results suggest the possible involvement of JNK pathway in genistein induced AP-1 activity while the ERK pathway seems to play an important role in kaempferol induced AP-1 activity.

Subfreezing Absorption Refrigeration for Industrial CHP

Gopalakrishnan Anand,Donald C Erickson,Ellen Makar 대한설비공학회 2018 International Journal Of Air-Conditioning and Refr Vol.26 No.4

The design and operation of an advanced absorption refrigeration unit (Thermochiller) as part of an industrial combined heat and power (CHP) system is presented. The unit is installed at a vegetable processing plant in Santa Maria, California. The overall integrated system includes the engine package with waste heat recovery, Thermochiller, cooling tower, and chilling load interface. The unique feature of the system is that both the exhaust and jacket heat are used to supply subfreezing refrigeration. To achieve the low refrigeration temperatures of interest to industrial applications, all components of this integrated system needed careful consideration and optimization. The CHP system has a low emission natural gas-fired 633kW reciprocating engine cogeneration package. Both the exhaust heat and jacket heat are recovered and delivered via a hot glycol loop with 105 ∘ C supply temperature and 80 ∘C return. The 125 ton ammonia absorption chiller (TC125) chills propylene glycol to −6 ∘ C and has a coefficient of performance of 0.63. TC125 has peak electric demand of 10 kW for pumps and 8 kW for the cooling tower fan. The CHP system, including TC125, operates 20 h per day, six days per week. All operations of TC125 are completely automatic and autonomous, including startups and shutdowns. Industrial refrigeration is typically a 24/7 load and highly energy-intensive. By converting all the engine waste heat to subfreezing refrigeration, Thermochiller brings added value to cogeneration or CHP projects.

Gallbladder perforation

Gopalakrishnan Gunasekaran,Debasis Naik,Ashwani Gupta,Vimal Bhandari,Manigandan Kuppusamy,Gaind Kumar,Niuto S Chishi 한국간담췌외과학회 2015 한국간담췌외과학회지 Vol.19 No.1

Backgrounds/Aims: Gallbladder perforation is a rare but potentially fatal disease. We herein present our clinical experience in diagnosis and management of 32 cases of gallbladder perforation. Methods: This retrospective study was conducted with inclusion of all cases of gallbladder perforation that presented to our hospital from January 2012 to November 2014. Cases of traumatic gallbladder perforation and patients younger than 12 years of age were excluded from this study. Results: This study included 32 patients (13 males and 19 females). The mean age of patients was 55.9 years. Gallbladder perforation was most common in the 5th and 6th decade of life. The mean age of patients with type I, II, and III gallbladder perforation was 57.0 years, 57.6 years, and 49.8 years, respectively. The most common site of perforation was the fundus, followed by the body and Hartmann’s pouch (24 : 5 : 2). Most of the type I gallbladder perforations were diagnosed intraoperatively, type II gallbladder perforations were diagnosed by enhanced abdominal computed tomography, and type III gallbladder perforations were diagnosed during laparoscopic cholecystectomy converted to open cholecystectomy for cholelithiasis. Mortality was highest in patients with type I gallbladder perforation. The mean hospital stay was 10.1 days, 6.4 days, and 9.2 days in patients with type I, II, and III gallbladder perforation, respectively. The histopathologic analysis in 28 patients who were operated on showed acute cholecystitis in 19 cases, acute-on-chronic cholecystitis in 4 cases, chronic cholecystitis in 4 cases, and mucinous adenocarcinoma of the gallbladder in a single case. Conclusions: Gallbladder perforation represents a special diagnostic and surgical challenge. Appropriate classification and management are essential.