Neuropeptide Y level in paraventricular nucleus of experimental diabetic rats: correlation with sympathetic activity and body weight

Neuropeptide Y (NPY), colocalized with norepinephrine neuron, is known to modulate sympathetic activity and feeding behavior. Although experimental type 1 diabetes has increased sympathetic activity at the early part of the disease process, little effort was made so far to understand the correlation between NPY level in the hypothalamus and sympathetic activity in diabetes. Male Sprague Dawley rats were made diabetic by a single injection of streptozotocin (65 mg/kg body weight, IV). The animals were then studied after 2, 4, and 8 weeks. Control animals received only citrate vehicle. In an effort to clarify the modulatory effect of NPY at the early stage of diabetes, the paraventricular nucleus (PVN) of hypothalamus was sampled by microdialysis for NPY and norepinephrine level. While NPY level was increased immediately within 2 weeks (along with feeding behavior), norepinephrine level was increased only after 8 weeks following injection of streptozotocin. The animals lost significant weight. These results are interpreted to mean that a strong correlation exists between the feeding behavior and NPY level in PVN. Since NPY is known to inhibit sympathetic activity it is possible that NPY receptors are down-regulated following diabetes. The higher level of norepinephrine indicating higher sympathetic activity did not allow the animals to gain weight. In addition, controversy exists regarding pleiotropic activities of NPY related to the feeding behavior of these animals

Atmospheric water vapor condensation on engineered interfaces: Busting the myths

Condensing atmospheric water vapor on surfaces is a sustainable approach to potentially address the potable water crisis. However, despite extensive research, a key question remains: what is the physical mechanism governing the condensation from humid air and how significantly does it differ from pure steam condensation? The answer may help define an optimal combination of the mode and mechanism of condensation as well as the surface wettability for best possible water harvesting efficacy. Here we show that this lack of clarity is due to the differences in heat transfer characteristics during condensation from pure vapor and humid air environments. Specifically, during condensation from humid air, the thermal resistance across the condensate is non-dominant and the energy transfer is controlled by vapor diffusion and condensate drainage. This leads to filmwise condensation on superhydrophilic surfaces, offering the highest water collection efficiency. To demonstrate this, we measured condensation rate on different sets of superhydrophilic and superhydrophobic surfaces in a wide degree of subcooling (10 - 26 C) and humidity-ratio differences (5 - 45 g/kg of dry air). The resulting condensation rate is enhanced by 57 - 333 % on the superhydrophilic surfaces as compared to the superhydrophobic ones. The findings of this study challenges the nearly century-old scientific ambiguity about the mechanism of vapor condensation from humid air. Our findings will lead to the design of efficient atmospheric water harvesting systems

Preferred Mode of Atmospheric Water Vapor Condensation on Nanoengineered Surfaces: Dropwise or Filmwise?

Condensing atmospheric water vapor on surfaces is a sustainable approach to addressing the potable water crisis. However, despite extensive research, a key question remains: what is the optimal combination of the mode and mechanism of condensation as well as the surface wettability for the best possible water harvesting efficacy? Here, we show how various modes of condensation fare differently in a humid air environment. During condensation from humid air, it is important to note that the thermal resistance across the condensate is nondominant, and the energy transfer is controlled by vapor diffusion across the boundary layer and condensate drainage from the condenser surface. This implies that, unlike condensation from pure steam, filmwise condensation from humid air would exhibit the highest water collection efficiency on superhydrophilic surfaces. To demonstrate this, we measured the condensation rates on different sets of superhydrophilic and superhydrophobic surfaces that were cooled below the dew points using a Peltier cooler. Experiments were performed over a wide range of degrees of subcooling (10–26 °C) and humidity-ratio differences (5–45 g/kg of dry air). Depending upon the thermodynamic parameters, the condensation rate is found to be 57–333% higher on the superhydrophilic surfaces compared to the superhydrophobic ones. The findings of the study dispel ambiguity about the preferred mode of vapor condensation from humid air on wettability-engineered surfaces and lead to the design of efficient atmospheric water harvesting systems

Fabrication of Directional Coupler Using SU-8 Wire Waveguide by Optical Lithography

Optical directional coupler is fabricated and characterized using SU-8 wire-waveguides; waveguides are being operated in single-mode region. While processing lithography steps, some of the problems and their approached solutions are also discussed

Development of micro-ring resonator-based optical bandpass filter using SU8 polymer and optical lithography

Laterally-coupled SU-8 ridge waveguide-based micro-ring resonator was designed, fabricated and characterized for optical filtering applications. Fabrication was done by optical lithography using a patterned chrome mask of SU-8 ridge waveguide and micro-ring resonator structures, which was replicated onto a plasma enhanced chemical vapour deposited (PECVD) silicon-dioxide layer on a silicon wafer. Optical characterization showed that the fabricated micro-ring resonator had a free spectral range (FSR) of ∼16 nm for a ring radius of 15 μm in TE polarization. A simple semiconductor laser diode and a monochromator were used for the characterization of the device. The measured through port and drop port light output for different wavelengths indicate that the device can be used as an optical filter around 1565 nm centre wavelength, with a 3 dB bandwidth of 5.3 nm and an extinction ratio of ∼10.5 dB

A 1 × 2 polarization-independent power splitter using three-coupled silicon rib waveguides

This work presents the development of a three-waveguide polarization-independent 1 × 2 power splitter using the silicon-on-insulator platform. Design of the device was accomplished by the effective index based matrix method and coupled mode theory. The component was fabricated using a readily available silicon-on-insulator substrate of a 5 μm thick device layer and characterized at 1.55 μm wavelength of light. The fabricated device has an insertion loss of 11.43 dB for transverse electric (TE) polarization and 11.80 dB for transverse magnetic (TM) mode, which indicates its polarization-independent behavior. The power splitting shows an imbalance of 0.23 dB for the TE mode and 0.82 dB for TM mode, which is due to the fabrication error of the separation of outer arms from the central input waveguide. The design can be extended for any 1 × 2N 3-dB power splitter, which will be very useful for optical interconnects and fiber-optic communication networks

Group A streptococcal sore throat in a periurban population of northern India: a one-year prospective study

OBJECTIVE: To estimate the incidence and risk factors of group A streptococcus (GAS) sore throat among school-aged children living in a periurban slum area of Chandigarh, North India. METHODS: A total of 536 children aged 5-15 years from 261 families identified by a systematic random selection method were enrolled in the study. Episodes of sore throat were recorded through fortnightly home visits over a one-year period. The local vernacular (Hindi) terms gala kharab (bad throat) and khansi jukam (cough and cold) were used to identify symptoms of sore throat, and throat swab specimens were collected from children who had these symptoms on the day of the home visit. Bacterial culture was carried out and the isolation of GAS was confirmed using group-A-specific antiserum. FINDINGS: The incidences of sore throat and GAS sore throat were, respectively, 7.05 and 0.95 episodes per child-year. The incidence was higher in the following situations: among 11-year-olds, during the winter (November to January) and rainy (August) months (a bimodal peak), among children living in houses where there was no separate room for the kitchen, and in homes that included a tobacco smoker. CONCLUSION: The results show that the incidence of GAS sore throat was related to age, season, and indoor air pollution