High-frequency partial liquid ventilation in respiratory distress syndrome: hemodynamics and gas exchange

Partial liquid ventilation using conventional ventilatory schemes improves lung function in animal models of respiratory failure. We examined the feasibility of high-frequency partial liquid ventilation in the preterm lamb with respiratory distress syndrome and evaluated its effect on pulmonary and systemic hemodynamics. Seventeen lambs were studied in three groups: high-frequency gas ventilation (Gas group), high-frequency partial liquid ventilation (Liquid group), and high-frequency partial liquid ventilation with hypoxia-hypercarbia (Liquid-Hypoxia group). High-frequency partial liquid ventilation increased oxygenation compared with high-frequency gas ventilation over 5 h (arterial oxygen tension 253 +/- 21.3 vs. 17 +/- 1.8 Torr; P < 0.001). Pulmonary vascular resistance decreased 78% (P < 0.001), pulmonary blood flow increased fivefold (P < 0.001), and aortic pressure was maintained (P < 0.01) in the Liquid group, in contrast to progressive hypoxemia, hypercarbia, and shock in the Gas group. Central venous pressure did not change. The Liquid-Hypoxia group was similar to the Gas group. We conclude that high-frequency partial liquid ventilation improves gas exchange and stabilizes pulmonary and systemic hemodynamics compared with high-frequency gas ventilation. The stabilization appears to be due in large part to improvement in gas exchange.     

Topology Management Ensuring Reliability in Delay Sensitive Sensor Networks with Arbitrary Node Failures

The lifetime of a sensor network is influenced by the efficient utilization of the resource constrained sensor nodes. The tree-based data gathering offers good quality of service (QoS) for the running applications. However, data gathering at the sink reduces the network lifetime due to a fast failure of highly loaded nodes. Loss of connectivity and sensing coverage affect the performance of the applications that demand critical QoS. In this paper, a data gathering tree management scheme has been proposed to deal with arbitrary node failures in delay-sensitive sensor networks. A load-balanced distributed BFS tree construction procedure has been introduced for an efficient data gathering. Based on the initial tree construction, a tree maintenance scheme and an application message handler have been designed to ensure the reliable delivery of the application messages. The correctness of the proposed scheme has been verified both theoretically and with the help of simulation. The proposed scheme offers low overhead, enhanced network lifetime and good QoS in terms of delay and reliability of the application messages.     

An empirical approach towards characterization of encrypted and unencrypted VoIP traffic

Multimedia Tools and Applications - VoIP traffic classification plays a major role towards network policy enforcements. Characterization of VoIP media traffic is based on codec behaviour. With the...     

Adaptive Comfort Degree-Days: A metric to compare adaptive comfort standards and estimate changes in energy consumption for future UK climates

This paper introduces the concept of the Adaptive Comfort Degree-Day, a temperature difference/time composite metric, as a means of comparing energy savings from Adaptive Comfort Model standards by quantifying the extent to which the temperature limits of the thermal comfort zone of the Predicted Mean Vote Model can be broadened. The Adaptive Comfort Degree-Day has been applied to a series of climates projected for different locations (Edinburgh, Manchester and London) under different emissions scenarios in the United Kingdom for the 2020s, 2030s, 2050s and 2080s. The rate at which energy savings can be achieved by the European adaptive standard EN15251 (Category II) was compared with the ASHRAE 55 adaptive standard (80% acceptability) during the cooling season. Results indicate that the wider applicability of the European standard means that it can realise levels of energy savings which its counterpart ASHRAE adaptive standard would not achieve for decades.     

Inherent Thermometry in a Hybrid Superconducting Tunnel Junction

We discuss inherent thermometry in a Superconductor-Normal metal-Superconductor tunnel junction. In this configuration, the energy selectivity of single-particle tunneling can provide a significant electron cooling, depending on the bias voltage. The usual approach for measuring the electron temperature consists in using an additional pair of superconducting tunnel junctions as probes. In this paper, we discuss our experiment performed on a different design with no such thermometer. The quasi-equilibrium in the central metallic island is discussed in terms of a kinetic equation including injection and relaxation terms. We determine the electron temperature by comparing the micro-cooler experimental current-voltage characteristic with isothermal theoretical predictions. The limits of validity of this approach, due to the junctions asymmetry, the Andreev reflection or the presence of sub-gap states are discussed.     

Removal of Cr(VI) using co-immobilized activated carbon and <Emphasis Type="Italic">Bacillus subtilis</Emphasis>: fixed-bed column study

Fixed-bed column studies were conducted to evaluate the potential of co-immobilized (activated carbon and Bacillus subtilis) (CI) beads for the removal of Cr(VI) from aqueous solution. The impact of various parameters such as initial Cr(VI) concentrations (100, 150, and 200 mg/L), flow rate (3, 9, and 15 mL/min), and bed depth (10, 15, and 20 cm) on Cr(VI) adsorption onto CI beads were investigated. The breakthrough time increased with a decrease in initial Cr(VI) concentration and flow rate, and an increase in bed height. The breakthrough data obtained for Cr(VI) removal was more adequately described by the Thomas model with high correlation coefficients (R ² = 0.982). The eluent, 0.1 M NaOH, provided high elution efficiencies (~90 %) in all the six cycles. Obtained results pointed out that CI beads could potentially be used for the removal of Cr(VI) from aqueous solution.     

Structure and properties of diffusion bonded transition joints between commercially pure titanium and type 304 stainless steel using a nickel interlayer

The solid-state diffusion bonding was carried out between commercially pure titanium and Type 304 stainless steel using nickel as an interlayer in the temperature range of 800–900 °C for 9 ks under 3 MPa load in vacuum. The transition joints thus formed were characterized in the optical and scanning electron microscopes. The inter-diffusion of the chemical species across the diffusion interfaces were evaluated by electron probe microanalysis. TiNi₃, TiNi and Ti₂Ni are formed at the nickel–titanium (Ni–Ti) interface; however, the stainless steel–nickel (SS–Ni) diffusion interface is free from intermetallic compounds up to 850 °C temperature. At 900 °C, the Ni–Ti interface exhibits the presence of α-β Ti discrete islands in the matrix of Ti₂Ni and λ + χ + α-Fe, λ + FeTi and λ + FeTi + β-Ti phase mixtures occur at the SS–Ni interface. The occurrence of different intermetallics are confirmed by the x-ray diffraction technique. The maximum tensile strength of ∼276 MPa and shear strength of ∼209 MPa along with 7.3% elongation were obtained for the diffusion couple processed at 850 °C. At the 900 °C joining temperature, the formation of Fe–Ti base intermetallics reduces the bond strength. Evaluation of the fracture surfaces using scanning electron microscopy and energy dispersive spectroscopy demonstrates that failure takes place through Ni–Ti interface up to 850 °C and through the SS–Ni interface of the joint when processed at 900 °C.     

Nanostructured Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–ZrO<Subscript>2</Subscript> composite synthesized by sol–gel technique: powder processing and microstructure

Al₂O₃–ZrO₂ composite gel powder was prepared by sol–gel route. The gel precursor compositions were preferred to achieve yield of 5–15 mol% zirconia after calcination of respective powders. The precursor gel was characterized by Differential Thermal Analysis (DTA)/Thermo Gravimetric (TG), IR and X-ray Diffraction study (XRD). The analysis reveal the gel contained pseudoboehmite and amorphous Zr(OH)₄, which was decomposed in three and two stages respectively. The phase transformation of alumina during calcination followed the sequence of pseudoboehmite → bayerite → boehmite → γ-Al₂O₃ → θ-Al₂O₃ → α-Al₂O₃, while that of ZrO₂ follows amorphous ZrO₂ → t-ZrO₂ → (t + m) ZrO₂. Fourier Transform Infrared Spectroscopy (FTIR) studies showed that the number of M–OH and M–O bond increases with zirconia due to a change in the cationic charge of the composite powder. Transmission Electron Microscopy (TEM) photograph of calcined powder exhibited the presence of dispersed as well as agglomerated nano sized spherical particles. SEM and Electron Probe Microscope Analysis (EPMA) confirmed the near uniform distribution of zirconia particles in the alumina matrix.     

Biosorption of chromium(VI) using Bacillus subtilis SS-1 isolated from soil samples of electroplating industry

Soils around the electroplating industry are often polluted with metals. The aim of the study was to assess Cr(VI) adsorption potential of chromium-resistant bacteria isolated from soil samples collected in and around electroplating industry, Coimbatore, India. A total of six morphologically different chromium-resistant bacteria were isolated from the soil samples and assayed for resistance to Cr(VI). Isolate designated SS-1 exhibited maximum resistance to Cr(VI) (600 mg/l) and subsequently identified as Bacillus subtilis based on the morphology, phenotypic characters, and partial 16S rDNA sequences. Batch experiments were carried out as a function of time, initial Cr(VI) concentration (100 mg/l), pH (2), and biosorbent dose (0.1 g/l). The maximum percentage of Cr(VI) removal was found to be 98.7 %. The experimental data showed a better fit with Langmuir model over Freundlich model throughout the range of initial concentrations. The kinetic models were examined with pseudo-first-order and pseudo-second-order kinetics. Fourier transform infrared spectroscopy studies confirmed the involvement of carboxyl and amide groups in Cr(VI) adsorption. Scanning electron microscopic studies revealed that nature of the bioadsorbent was altered after Cr(VI) adsorption. The results revealed that Cr(VI) was considerably adsorbed onto bacterial biomass, and it could be an economical method for the removal of Cr(VI) from aqueous solution.     

Electrochemical Study of Diffusion Bonded Joints between Micro-duplex Stainless Steel and Ti6A14V Alloy

In the present study,corrosion behavior of diffusion bonded joints formed between micro-duplex stainless steel(MDSS) and Ti6AI4V alloy(TiA)(at 900 ℃ for 60 min under 4 MPa uniaxial pressure in vacuum) was investigated in 1 mol/L HCI and 1 mol/L NaOH solutions using various electrochemical measurements such as open circuit potential(OCP),electrochemical impedance spectroscopy(EIS) and potentiodynamic polarization(PD).For comparison,corrosion behavior of base metals(MDSS and TiA) was also evaluated.Bonded joint was characterized by light optical microscopy and scanning electron microscopy using backscattered electron mode.The layer wise σ phase and λ + FeTi phase mixture has been observed at the bond interface and the bond tensile strength and shear strength were ~556.4 MPa and ~420.2 MPa,respectively.