Tuning whispering gallery lasing modes from polymer fibers under tensile strain

Wavelength tuning of whispering gallery lasing modes has been observed from Rhodamine-B-doped polymer fibers under tensile strain. Good quality whispering gallery lasing modes are produced from both solid and hollow fibers by transverse optical pumping. The lasing modes are shifted linearly toward the shorter wavelength side when the fiber is elongated in the axial direction. Compared with solid fiber, the lasing modes of hollow fiber can be tuned over the entire gain spectrum with a tuning range of ∼5  nm. It is found that the tuning of the lasing modes of hollow fiber is reversible.

Effect of thermal processing on the biochemical constituents of green mussel (Perna viridis) in Tin-free-steel cans

The effect of thermal processing on the biochemical constituents of green mussel (Pernaviridis) in brine was investigated. Depurated mussel samples were thermal processed in tin-free steel cans (TFS) at F0 8.43. The time temperature data was collected during heat processing using EVAL data recorder and heat penetration characteristics were determined using formula method. The total process time was 27.48 min and the processed cans were found to be commercially sterile. The mineral composition of processed mussel was significantly higher than raw samples. The instrumental texture analysis indicated that product become soft after thermal processing.The thermal process led to a significant decrease in total amino acid and fatty acid content of the samples. Even though the samples showed a decrease in amino acid and fatty acid composition after thermal processing, the mussel meat was nutritionally well balanced with respect to essential anino acids and fatty acids.Hence the product can be considered as a food source with high quality protein and fat to fulfil consumer's requirements.Based on sensory analysis, the processed products were found acceptable during the study period.

Nanoscale lithography of LaAlO₃/SrTiO₃ wires using silicon stencil masks

We have developed a process to fabricate low-stress, fully crystalline silicon nanostencils, based on ion irradiation and the electrochemical anodization of p-type silicon. These nanostencils can be patterned with arbitrary feature shapes with openings hundreds of micrometers wide connected to long channels of less than 100 nm in width. These nanostencils have been used to deposit (2.5 μm- to 150 nm-wide) lines of LaAlO3 (LAO) on a SrTiO3 (STO) substrate, forming a confined electron layer at the interface arising from oxygen vacancies on the STO surface. Electrical characterization of the transport properties of the resulting LAO/STO nanowires exhibited a large electric field effect through back-gating using the STO as the dielectric, demonstrating electron confinement. Stencil lithography incorporating multiple feature sizes in a single mask shows great potential for future development of oxide electronics.

Smoking and Thromboangitis Obliterans- Are they related ?

INTRODUCTION

In 1908 Leo Buerger first gave the world the clinical picture of this dreadful disease which he called Thromboangitis Obliterans. Virtually all investigators believe that smoking or tobacco use in some form is a requirement for the diagnosis of Thromboangitis Obliterans. We studied the demographic profile and smoking pattern of patients with Thromboangiitis Obliterans.

METHODS

Retrospective study carried out in a tertiary level hospital of South India from 1st January 1997 to 31st December 2003. Patients fulfilling Shionoya's criteria form the study group. Incidence of Thromboangitis Obliterans, relation to smoking habits, type and nature of manifestation were analyzed.

RESULTS

A total of 105 cases were studied and found to have declining pattern of incidence from 0.9%-0.3%. All patients were males, smokers at the time admission and 76% out of them were from low socioeconomic background. Patients smoking 5-15 cigarettes per day, for 5-10 years duration constituted 45% of the study group. The most frequent reasons for being referred to hospital were ischemic ulcers (83.80%), claudication (78.0%) and rest pain (26.66%).

CONCLUSIONS

In those who present early with the disease the number of cigarettes and duration of smoking shows no direct correlation to the severity. Most patients continue to smoke inspite of counseling and awareness that the disease progresses due to smoking. Ulcer, intermittent claudication and rest pain are the three common presenting symptoms of Thromboangitis Obliterans.

Laser emission from the whispering gallery modes of a graded index fiber

Whispering gallery mode (WGM) laser emission has been observed from rhodamine B doped polymer optical graded index (GI) fiber by transverse pumping with a frequency doubled Q-switched Nd:YAG laser. The propagation and confinement of these modes were also observed. A variation in the free spectral range from 0.29 to 1.24 nm is obtained along the length due to the confinement of WGMs in the GI fiber.

Large area resist-free soft lithographic patterning of graphene

Large area low-cost patterning is a challenging problem in graphene research. A resist-free, single-step, large area and cost effective soft lithographic patterning strategy is presented for graphene. The technique is applicable on any arbitrary substrate that needs to be covered with a graphene film and provides a viable route to large-area patterning of graphene for device applications.

Antiaging effect of dietary chitosan supplementation on glutathione-dependent antioxidant system in young and aged rats

Aging has been defined as the changes that occur in living organisms with the passage of time that lead to functional impairment and ultimately to death. Free radical-induced oxidative damage has long been thought to be the most important consequence of the aging process. In the present study, an attempt has been made to study the salubrious effects of dietary supplementation of chitosan on glutathione-dependent antioxidant defense system in young and aged rats. The dietary supplementation of chitosan significantly reduced the age-associated dyslipidemic abnormalities noted in the levels of total cholesterol, HDL-cholesterol, and LDL-cholesterol in plasma and heart tissue. Its administration significantly (P < 0.05) attenuated the oxidative stress in the heart tissue of aged rats through the counteraction of free radical formation by maintaining the enzymatic [glutathione peroxidase (GPx) and glutathione reductase (GR)] and non-enzymatic [reduced glutathione (GSH)] status at levels comparable to that of normal young rats. Our results conclude that dietary intake of chitosan restores the depleted myocardial antioxidant status and suggest that it could be an effective therapeutic agent in treatment of age-associated disorders where hypercholesterolemia and oxidative stress are the major causative factors.

Natural radioactivity content in soil and indoor air of Chellanam

Contribution of terrestrial radiation due to the presence of naturally occurring radionuclides in soil and air constitutes a significant component of the background radiation exposure to the population. The concentrations of natural radionuclides in the soil and indoor air of Chellanam were investigated with an aim of evaluating the environmental radioactivity level and radiation hazard to the population. Chellanam is in the suburbs of Cochin, with the Arabian Sea in the west and the Cochin backwaters in the east. Chellanam is situated at ∼25 km from the sites of these factories. The data obtained serve as a reference in documenting changes to the environmental radioactivity due to technical activities. Soil samples were collected from 30 locations of the study area. The activity concentrations of (232)Th, (238)U and (40)K in the samples were analysed using gamma spectrometry. The gamma dose rates were calculated using conversion factors recommended by UNSCEAR [United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. UNSCEAR (2000)]. The ambient radiation exposure rates measured in the area ranged from 74 to 195 nGy h(-1) with a mean value of 131 nGy h(-1). The significant radionuclides being (232)Th, (238)U and (40)K, their activities were used to arrive at the absorbed gamma dose rate with a mean value of 131 nGy h(-1) and the radium equivalent activity with a mean value of 162 Bq kg(-1). The radon progeny levels varied from 0.21 to 1.4 mWL with a mean value of 0.6 mWL. The thoron progeny varied from 0.34 to 2.9 mWL with a mean value of 0.85 mWL. The ratio between thoron and radon progenies varied from 1.4 to 2.3 with a mean of 1.6. The details of the study, analysis and results are discussed.

The immunogenic characteristics associated with multivalent display of Vi polysaccharide antigen using biodegradable polymer particles

Polysaccharides in their great majority are thymus-independent (TI) antigens. Anti-polysaccharide antibody responses are generally weak and characterized by lack of memory, isotype restriction and delayed ontogeny. We report here the generation of protective memory antibody response by multivalent display of polysaccharide antigens on biodegradable polymeric particles. Single dose immunization using polylactide (PLA) polymer particles entrapping Vi capsular polysaccharide antigen from Salmonella typhi promoted isotype switching and induced polysaccharide-specific memory antibody response in experimental animals. PLA nanoparticles as well as microparticles entrapping Vi polysaccharides elicited high IgG titer in comparison to soluble Vi immunization. Immunizations with particles co-entrapping both Vi polysaccharide and tetanus toxoid did not improve the anti-polysaccharide antibody responses. Lower antibody response from co-entrapped formulation was mostly due to inhibition of particle phagocytosis by the macrophages. Immunization using polylactide particles entrapping only Vi polysaccharide with higher density on surface elicited highest secondary antibody response as well as promoted isotype switching. The vaccination potential of particle based immunizations was further confirmed by the generation of quick memory antibody responses while challenging the immunized animals with live S. typhi. This approach provides a multivalent display of polysaccharide antigen using polymer particles and elicits protective memory antibody response without conjugation to a carrier protein.