Papers by Gopalkrishna Bhat
The optimum self-focussing materials with an intensity-dependent refractive index and the realiza... more The optimum self-focussing materials with an intensity-dependent refractive index and the realization of the ability of these materials to produce intensity dependent phase shift in all-optical photonic devices have become a topic of continuous investigation. Many organic materials including dye-doped polymer films are creating interest due to their advantages in terms of enhanced efficiency, and optimum mechanical properties to fabricate reliable devices. In this paper, we have studied the nonlinear optical properties like nonlinear absorption and nonlinear refraction of a two-photon fluorescent dye DASPB doped in Polymethyl methacrylate-methacrylic acid (PMMA-MA) polymer matrix using open aperture and closed aperture Z-scan experimental methods by means of low power continuous wave (CW) laser beam. The optical limiting properties of these films are also studied using Type 1 and Type 2 configurations at different input powers using continuous wave (CW) laser beams of 532 nm wavelength. The nonlinear refractive index n 2 , nonlinear absorption coefficient β, changes in refractive index with input intensity, and the magnitude of third-order optical nonlinearity of the dye-doped film are experimentally determined. The saturated output power for type 1 and type 2 optical limiting are determined. The input limiting threshold and saturated output power level for both type 1 and type 2 optical limiting configurations are recorded. DASPB dye-doped in PMMA-MA polymer film has shown saturation absorption at lower input irradiance and reverse saturation absorption along with two-photon absorption at higher input irradiance and hence found to be a potential candidate for the third harmonic property based photonic devices. Keywords : Organic Nonlinear material, Dye-doped polymer films, Optical limiting, Open and closed aperture Z scan. DASPB doped PMMA-MA films.
Materials with exceptional third order nonlinear optical properties are critical to the continuin... more Materials with exceptional third order nonlinear optical properties are critical to the continuing development of photonics and electro-optical devices such as those used in optical communications, networking, optical computation for signal processing, and data storage devices. The nonlinear optical material research is generally focussed on improving the efficiency of optical wavelength conversion, optical amplification, nonlinear absorption, refractive index changes etc. which are input light intensity dependent. During last few years, the organic dye-doped polymer films are getting more attention due to their advantages in fabricatingoptimum photonics devices. In this paper, we have studied the nonlinear optical properties like nonlinear absorption and nonlinear refraction of an azo dye Disperse Orange-25 (DO-25) doped in Polymethyl methacrylate-methacrylic acid (PMMA-MA) polymer matrix using open aperture and closed aperture Z-scan experimental methods for continuous wave (CW) laser input. The optical limiting properties of these films are also studied using Type 1 and Type 2 configurations at different input power using continuous wave (CW) laser beams of 532 nm wavelength.The nonlinear absorption coefficient, nonlinear refractive index, and saturated output power for type 1 and type 2 optical limiting are determined.
Molecules with high two-photon absorption (TPA) cross section and the molecules which have revers... more Molecules with high two-photon absorption (TPA) cross section and the molecules which have reverse saturation absorption (RSA) cross section are of great interest today because of their application in three-dimensional optical data storage and photonic switches. During last forty years, several techniques have been developed to determine the two-photon absorption cross-sections and reverse saturation absorption cross-sections of the materials. This includes direct methods, such as nonlinear transmission and Z-scan methods and indirect methods, such as two-photon excited fluorescence and two-photon pump-probe transient absorption spectroscopy. During recent years, the organic dye-doped polymer films getting more attention due to their advantages to fabricate photonics devices. In this paper, we have studied the nonlinear optical properties like nonlinear absorption and nonlinear refraction of an azo dye Disperse yellow-7 (DY-7) doped in Polymethyl methacrylate-methacrylic acid (PMMA-MA) polymer matrix using open aperture and closed aperture Z-scan experimental methods using continuous wave (CW) laser. The optical limiting properties of these films are also studied in Type 1 and Type 2 configurations at different input power using continuous wave (CW) laser beams of 532 nm wavelength.
Indian Journal of Dermatology Venereology and Leprology
Study of 30 male consorts of 30 cases of vaginal trichomoniasis with high levels of parasitic inf... more Study of 30 male consorts of 30 cases of vaginal trichomoniasis with high levels of parasitic infection was undertaken to evaluate the sexually transmitted role of trichomoniasis in sex partners. There were 20 symptomatic and 10 asymptomatic male partners, who revealed T. vaginalis in 80.0% and 60.0 of the cases respectively and the overall prevalence was 73.3% (22 Of 30). T. vaginalis was detected in 83.3% male with urethritis and 50.0% males with prostatitis. Detection of trichomonas in urethral discharge, morning drop secretion, urine deposit and prostatic fluid was 80.0%, 50.0% 35.7% and 21.4% in that order. It is evident from these results that the sex consorts of all cases of trichomoniasis should be considered as harbouring T. vaginalis in their genito-urinary tract as carriers and be treated to break the chain of transmission. Fontanna smear was superior to culture and wet mount in the detection of T. vaginalis, the success rates being 73.3%, 63.3% and 53.3%. A good correlation was observed between smear and culture at high levels of parasitic infection.
Indian journal of experimental biology
A chemically defined medium has been described which supported good growth of S. aureus. Optimal ... more A chemically defined medium has been described which supported good growth of S. aureus. Optimal production of different exoproteins, viz. coagulase, acid phosphatase, proteinase, lipase, beta-lactamase and alpha-toxin was recorded in the medium.
Indian Journal of Medical Microbiology
... Dear Editor, Street food refers to a variety of food and beverages prepared and sold by vendo... more ... Dear Editor, Street food refers to a variety of food and beverages prepared and sold by vendors in streets and other public places for immediate consumption. Selling street foods is an important occupation in many cities in developing countries. ...
The Journal of communicable diseases
Over 30% of the population in developing countries is in need of access to safe drinking water. T... more Over 30% of the population in developing countries is in need of access to safe drinking water. The 875 million cases of diarrhea and 4.6 million deaths that occur each year due to a lack of a safe water supply occur primarily in these countries. It is estimated that these countries will need over $150 billion to establish full drinking water supply system coverage, a sum that they may not be able to raise within the near future. Conventional methods of drinking water disinfection, such as chemical treatment, heat pasteurization, and filtration, require facilities, materials, and fuel that may not be readily available or feasible to attain. An alternative treatment option is to utilize solar energy, which has been shown to inactivate pathogens through pasteurization and radiation effects.
Indian Journal of Pathology and Microbiology, 2010
... Medicine 1994;73:69-78. 3. Horton CK, Haug L, Gooze L. Pseudoallescheria boydii infections in... more ... Medicine 1994;73:69-78. 3. Horton CK, Haug L, Gooze L. Pseudoallescheria boydii infections in AIDS. J Acquir Immuno Defic Syndr Hum Retroviraol 1999;20:200-11. 4. Hecht R, Montgomeire JZ. ... Bhat K. Gopalkrishna, Anusha Sara Philip, Sushreema, Shalini Shenoy ...
Acta Dermato-Venereologica, 2008
Sultan Qaboos University Medical Journal, 2016
Healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen wor... more Healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen worldwide and its multidrug resistance is a major concern. This study aimed to determine the clinical characteristics and antibiotic susceptibility profile of healthcare-associated MRSA with emphasis on resistance to macrolide-lincosamide-streptogramin B (MLSB) phenotypes and vancomycin. This cross-sectional study was carried out between February 2014 and February 2015 across four tertiary care hospitals in Mangalore, South India. Healthcare-associated infections among 291 inpatients at these hospitals were identified according to the Centers for Disease Control and Prevention guidelines. Clinical specimens were collected based on infection type. S. aureus and MRSA isolates were identified and antibiotic susceptibility tests performed using the Kirby-Bauer disk diffusion method. The minimum inhibitory concentration of vancomycin was determined using the Agar dilution method and inducible clindamycin resistance was detected with a double-disk diffusion test (D-test). Out of 291 healthcare-associated S. aureus cases, 88 were MRSA (30.2%). Of these, 54.6% were skin and soft tissue infections. All of the isolates were susceptible to teicoplanin and linezolid. Four MRSA isolates exhibited intermediate resistance to vancomycin (4.6%). Of the MRSA strains, 10 (11.4%) were constitutive MLSB phenotypes, 31 (35.2%) were inducible MLSB phenotypes and 14 (15.9%) were macrolide-streptogramin B phenotypes. Healthcare-associated MRSA multidrug resistance was alarmingly high. In routine antibiotic susceptibility testing, a D-test should always be performed if an isolate is resistant to erythromycin but susceptible to clindamycin. Determination of the minimum inhibitory concentration of vancomycin is necessary when treating patients with MRSA infections.
The Indian Journal of Medical Research
Drug resistance in enterococci isolated from hospitalized patients is reported. Out of 421 strain... more Drug resistance in enterococci isolated from hospitalized patients is reported. Out of 421 strains tested, 45 (10.7%) showed high level aminoglycoside resistance (HLAR). At the species level, 8.2 per cent of Enterococcus faecalis and 33.3 per cent of E. faecium were HLAR. While all the strains of E. faecalis were sensitive to vancomycin, one strain of E. faecium was vancomycin resistant.
Tropical Doctor
1. Trop Doct. 1995 Jul;25(3):127. Atypical Escherichia coli in urinary tract infection. BhatKG, B... more 1. Trop Doct. 1995 Jul;25(3):127. Atypical Escherichia coli in urinary tract infection. BhatKG, Bhat MG. Department of Microbiology, Kasturba Medical College, Mangalore, India. PMID: 7660484 [PubMed - indexed for MEDLINE] MeSH Terms: ...
The Indian Journal of Medical Research
Effect of iron in the form of ferric oxide (Fe2O3) on the survival of V. cholerae O1 was studied.... more Effect of iron in the form of ferric oxide (Fe2O3) on the survival of V. cholerae O1 was studied. V. cholerae O1 survived for 8 days in plain water whereas in presence of Fe2O3 it survived up to 15 days. Presence of organic material in the water further promoted the bacterial survival by at least 4 days. There was no difference between the behaviour of El Tor and classical biotype. These results indicate that the presence of iron in water could promote the survival of V. cholerae O1 in water and may play a significant role in the epidemiology of cholera.
The Indian Journal of Medical Research
A study was conducted to ascertain the prevalence of copper resistant Salmonella typhi isolates i... more A study was conducted to ascertain the prevalence of copper resistant Salmonella typhi isolates in south Karnataka. Of the 186 strains studied, 26 (13.97%) were found to be copper resistant. Among the copper resistant strains 19 (73.08%) were found multi drug resistant. All copper resistant strains remained uniformly sensitive to ceftriaxone, ciprofloxacin and norfloxacin. Multiple drug resistance was exclusively associated with E1 phage types.
Indian Journal of Pathology and Microbiology
... Issue Date: 25-Jul-2001. Citation: Ciraj AM, Bhat KG, Reddy V, Shivananda PG. Prototrophic va... more ... Issue Date: 25-Jul-2001. Citation: Ciraj AM, Bhat KG, Reddy V, Shivananda PG. Prototrophic variants of Salmonella typhi from South Karnataka and their antibiogram. Indian Journal of Pathology & Microbiology. 2001 Jul; 44(3): 385-6. Language: eng. Type: Journal Article. ...
Indian Journal of Pathology and Microbiology
Tropical Doctor
1. Trop Doct. 1998 Apr;28(2):106-7. Drug resistant enterococci in a south Indian hospital. BhatKG... more 1. Trop Doct. 1998 Apr;28(2):106-7. Drug resistant enterococci in a south Indian hospital. BhatKG, Paul C, Ananthakrishna NC. Department of Microbiology, Kasturba Medical College, Mangalore, India. PMID: 9594685 [PubMed - indexed for MEDLINE]. MeSH Terms: ...
Indian Journal of Medical Microbiology
Journal of Clinical and Diagnostic Research
ABSTRACT
Indian Journal of Pathology and Microbiology, 2015
The increased rate of infection by New Delhi metallo-beta-lactamases-1 (NDM1) producing Escherich... more The increased rate of infection by New Delhi metallo-beta-lactamases-1 (NDM1) producing Escherichia coli is a major concern since they show a high rate of drug resistance and are responsible for mortality and morbidity. To characterize the NDM1 producing E. coli isolates and their impact on patients' clinical outcome. This descriptive study was carried out in a multi-specialty tertiary care hospital. Three hundred nonrepeat strains of E. coli from inpatients were included in the study. Modified Hodge test and metallo-beta-lactamases (MBL) e-test were performed to detect carbapenemase and MBL activity. Polymerase chain reaction (PCR) technique was performed to detect NDM1. NDM1 positive isolates were further tested for plasmid mediated AmpC, blaCTX , blaSHV , blaTEM genes and also for phylogrouping by PCR methods. Treatment and patients' clinical outcome were also analyzed. Out of 300 isolates, 21 (7%) were MBL producers by phenotypic methods. Of this, 17 (81%) were NDM1 positives, among the NDM1 producers 6 (35%) isolates were belongs to phylogroups D followed by A 5 (29%), B1 4 (24%) and B2 2 (12%), 15 (88%) isolates were blaCTX-M positive suggestive of extended-spectrum beta lactamase producing strain and 7 (47%) were positive with CIT type of AmpC. With the follow-up of the patients, it was found that 12 (71%) recovered and 3 (18%) developed relapses, and mortality was seen in 2 (12%) patients. NDM1 producing isolates showed a high degree of drug resistance but can be treated with suitable antimicrobials, in the majority. Early detection and choice of appropriate antibiotics may help in reducing mortality and morbidity.
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Papers by Gopalkrishna Bhat