Autoregressive modeling of lung sounds: characterization of sourceand transmission

In this communication, we discuss the application of autoregressive modeling to lung sounds analysis. The lung sounds source in the airway is modeled as a white noise source, consisting of one or a combination of the following sources: random white noise sequence, periodic train of impulses, and impulsive bursts of energy. The acoustic transmission through the lung parenchyma and chest wall is modeled as an all-pole filter. Using this method, the source and transmission characteristics of lung sounds are estimated separately, based on the lung sounds at the chest wall. To illustrate the potential validity of the model, lung sound segments in known disease conditions were selected from teaching tapes and the source and transmission characteristics were estimated by applying the model. The estimated characteristics were found to be consistent with current knowledge of the generation and transmission of lung sounds in the known conditions.     

Thermoelectric power of single-phase samples of Tl2CaBa2Cu2O y and Ba2CaSr2Cu2O y

Single-phase 2122 samples of thallium and bismuth superconductors were made by the precursor matrix method. The thermopower of these samples was measured in the temperature range 250 K-T _c . The thermopower was positive and decreased linearly with increasing temperature aboveT _c (onset). The exponential enhancement of thermopower seen in the undoped and doped YBCO was not observed in these samples. The linear variation of thermopower can be explained on the basis of either a two-band model or a narrow band model.     

Micropatterning of Electrospun Polyurethane Fibers Through Control of Surface Topography

A novel technique was developed to control the deposition of electrospun polyurethane fibers using a silicone collector substrate patterned with soft lithography. This method can be used to control selective fiber deposition with broad pattern dimensions (50–500 µm) over a large area. The combination of ease of use, low cost, tunability, and generation of relatively large fiber mats available with this technique is expected to advance our ability to mimic the orientation and anisotropic properties of native tissues to generate improved tissue engineering scaffolds.

     

Traditional Kerala style fish curry in indigenous retort pouch

Fish curry processed in metal cans is popular in the overseas markets. An important limitation with the use of metal cans is the undesirable taste imparted to the products on storage. Flexible pouches are an ideal alternative to metal cans. Extensive work carried out at Central Institute of Fisheries Technology has been able to identify indigenous pouches, which are as good as imported pouches. This has been done after collecting different types of indigenous and imported flexible pouches, analyzing their composition and conducting detailed studies on their physical and food contact application properties. Two indigenous pouches with composition 12 micron polyester/12 micron aluminium foil/87.5 micron cast polypropylene and 12 micron polyester/15 micron aluminium foil/70 micron cast polypropylene have been selected and got made by indigenous laminators and an imported one with configuration 12 micron polyester/15 micron aluminium foil/75 micron cast polypropylene were used for further experiment on processing fish curry. Traditional Kerala style mackerel fish curry was processed in the retort pouches of the above configurations. About 220 g fish curry was packed in each pouch (15.5 cm×7 cm). Process requirements were worked out by measuring heat penetration using thermocouples introduced into the pouches. Fish curry processed to a F₀ value of 8.43 gave an acceptable product with desired texture and sensory characteristics. The physical properties of the pouches studied showed that the indigenous pouches of the above configurations were good enough to give a shelf life of 1 year at room temperature. The curry remained sterile throughout the storage period at ambient temperature (25–30°C) and retained acceptable sensory characteristics.     

Role of molecular interactions and structural defects in the efficient fluorescence quenching by carbon nanotubes

Fluorescence quenching effect of single walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) on three most common fluorophores fluorescein, rhodamine 6G and quinine sulphate has been studied and compared. Comparative studies of quenching efficiency shows that SWCNTs are more efficient fluorescence quencher than the MWCNTs. Nature of Stern–Volmer plot was found to be highly non-linear indicating combined effect of dynamic and static quenching. The contribution of dynamic quenching component was assessed through the fluorescence lifetime measurements. Studies on vacuum annealed SWCNTs with low defect contents suggest that structural defects primarily contribute to the large quenching. Fluorescence quenching was found to be dominant even in the cases where adsorption was low implying that surface adsorption play a minor role in the quenching, except for rhodamine 6G. Adsorption isotherms have been studied using Langmuir and Freundlich models. Freundlich model was found to be closer in behaviour implying a multilayer adsorption of molecules on the surface. The contributions of metal nanoparticles and carbon impurities present in different allotropic forms to the fluorescence quenching were also assessed. We speculate that defect mediated nonradiative energy transfer through dipole–dipole coupling may be the dominant mechanism of high efficiency quenching by SWCNTs.     

Thermal behavior and detonation properties of d3-hexanitrotrishomocubane

The DSC thermogram of the title compound (1) reveals the following characteristics: When a 3.34 mg sample of 1 was heated at 10°C-min^?1, exotherm onset occurred at 272°C, reached a maximum at 308°C, and subsided at 331°C. A second smaller exotherm was initiated at 331°C, reached a maximum at 338°C, and subsided at 355°C. A study of the shock sensitivity of 1 as measured by the exploding foil slapper technique revealed that 1 is less shock-sensitive than TNT. Explosive output calculations show that it is a substantially more powerful explosive than is TNT.     

Anomalies in hepatobiliary excretion of technetium-99m-MAG3 preparations

Technetium-99m-MAG3 is accepted as a renal tubular function agent. However, sporadic liver and gall bladder visualisation during its clinical use is clearly a disadvantage. HPLC-purified 99mTc-MAG3 samples exhibited appreciable hepatobiliary uptake (7%), and an elevated level of such uptake was observed in unpurified kit preparations, which was stated to be associated with the excretory property of the radiolabeled kit impurities. To verify this we attempted to quantitate the hepatobiliary uptake of the kit preparations with that of its radiolabeled components. The contribution of each component toward hepatobiliary uptake of the sample was calculated from their abundance in the chelate mixture and the individual biodistribution of the isolated components. However, the anticipated hepatobiliary uptake of different preparations of 99mTc-MAG3 calculated in this way was always lower than that of the experimental value determined directly. Further work is needed to explain the anomaly.     

Induced crystallization of cellulose in never-dried cotton fibers

In the present investigation, we have made a systematic study of the induced crystallization in never-dried cotton fiber, by allowing it to desiccate under different conditions of humidity and temperature. The resulting structural changes have been followed using x-ray diffraction and infrared absorption techniques. A slow rate of drying coupled with a high temperature was more conducive for maximum crystallization. Analysis of the effect of temperature on the induced crystallization showed possible existence of a thermal transition in cellulose around 30°C. The induced crystallization brought about by slow drying as well as those produced using intercrystalline swelling agents, have been shown to be resulting from a proper channelization of the interfibrillar mobility existing in the never-dried fibers.