Remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy: comparison of adjuvant propofol and ketamine

OBJECTIVE: Laryngoscopy and stimuli inside the trachea cause an intense sympatho-adrenal response. Remifentanil seems to be the optimal opioid for rigid bronchoscopy due to its potent and short-acting properties. The purpose of this study was to compare bolus propofol and ketamine as an adjuvant to remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy. MATERIALS AND METHODS: Forty children under 12 years of age who had been scheduled for a rigid bronchoscopy were included in this study. After midazolam premedication, a 1 µg/kg/min remifentanil infusion was started, and patients were randomly allocated to receive either propofol (Group P) or ketamine (Group K) as well as mivacurium for muscle relaxation. Anesthesia was maintained with a 1 µg/kg/min remifentanil infusion and bolus doses of propofol or ketamine. After the rigid bronchoscopy, 0.05 µg/kg/min of remifentanil was maintained until extubation. Hemodynamic parameters, emergence characteristics, and adverse events were evaluated. RESULTS: The demographic variables were comparable between the two groups. The decrease in mean arterial pressure from baseline values to the lowest values during rigid bronchoscopy was greater in Group P (p = 0.049), while the reduction in the other parameters and the incidence of adverse events were comparable between the two groups. The need for assisted or controlled mask ventilation after extubation was higher in Group K. CONCLUSION: Remifentanil-based total intravenous anesthesia with propofol or ketamine as an adjuvant drug along with controlled ventilation is a viable technique for pediatric rigid bronchoscopy. Ketamine does not provide a definite advantage over propofol with respect to hemodynamic stability during rigid bronchoscopy, while propofol seems more suitable during the recovery period

The design and fabrication of supramolecular semiconductor nanowires formed by benzothienobenzothiophene (BTBT)-conjugated peptides

π-Conjugated small molecules based on a [1]benzothieno[3,2-b]benzothiophene (BTBT) unit are of great research interest in the development of solution-processable semiconducting materials owing to their excellent charge-transport characteristics. However, the BTBT π-core has yet to be demonstrated in the form of electro-active one-dimensional (1D) nanowires that are self-assembled in aqueous media for potential use in bioelectronics and tissue engineering. Here we report the design, synthesis, and self-assembly of benzothienobenzothiophene (BTBT)–peptide conjugates, the BTBT–peptide (BTBT-C3–COHN-Ahx-VVAGKK-Am) and the C8-BTBT–peptide (C8-BTBT-C3–COHN-Ahx-VVAGKK-Am), as β-sheet forming amphiphilic molecules, which self-assemble into highly uniform nanofibers in water with diameters of 11–13(±1) nm and micron-size lengths. Spectroscopic characterization studies demonstrate the J-type π–π interactions among the BTBT molecules within the hydrophobic core of the self-assembled nanofibers yielding an electrical conductivity as high as 6.0 × 10−6 S cm−1. The BTBT π-core is demonstrated, for the first time, in the formation of self-assembled peptide 1D nanostructures in aqueous media for potential use in tissue engineering, bioelectronics and (opto)electronics. The conductivity achieved here is one of the highest reported to date in a non-doped state

Graphene-enabled adaptive infrared textiles

Interactive clothing requires sensing and display functionalities to be embedded on textiles. Despite the significant progress of electronic textiles, the integration of optoelectronic materials on fabrics remains as an outstanding challenge. In this Letter, using the electro-optical tunability of graphene, we report adaptive optical textiles with electrically controlled reflectivity and emissivity covering the infrared and near-infrared wavelengths. We achieve electro-optical modulation by reversible intercalation of ions into graphene layers laminated on fabrics. We demonstrate a new class of infrared textile devices including display, yarn, and stretchable devices using natural and synthetic textiles. To show the promise of our approach, we fabricated an active device directly onto a t-shirt, which enables long-wavelength infrared communication via modulation of the thermal radiation from the human body. The results presented here provide complementary technologies which could leverage the ubiquitous use of functional textiles

Thermoelectric Effects in Self-heating Silicon Microwires

Self-heating mechanisms of small-scale structures have been an important subject where electrical and thermal transports are coupled, such as many electronic and optoelectronic devices, micro-electro-mechanical systems (MEMS), thermoelectric energy conversion devices and phase-change memory devices. In this work, nanocrystalline silicon microwires (L: 1 – 30 μm, Width: 0.1 – 1 μm, Thickness: 50 – 130 nm) are self-heated either through a single, short duration (\u3c 1 μs) or longer DC/AC signal. The motivation behind this work is to melt the structures using electrical stress and to achieve larger crystalline domains (ultimately a single crystal domain) on the wires upon resolidification. Scanning electron micrographs show very smooth wire surfaces after the voltage pulse compared to as-fabricated nanocrystalline texture. Voltage-pulse induced self-heating leads to significant conductance improvement, suggesting crystallization of the wires. The minimum resistivity during the pulse extracted from wires of different dimensions matches previously reported values for liquid silicon. Hence, nanocrystalline silicon microwires melt through self-heating during the voltage pulse and resolidify upon termination of the pulse, resulting in very smooth and less-resistive crystalline structures. Strong thermoelectric effects are observed on self-heated wires as asymmetric self-heating and melting of the wires when a microsecond voltage pulse is applied to melt only some portion (~ 50 %) of the wires. This observation has shifted the focus of the work towards understanding of self-heating mechanisms and thermoelectric effects on these wires. The thermoelectric effects are also characterized through capture and analysis of light emission from the self-heated wires biased with DC/AC signals. The hottest spot on the wires consistently appears closer to the lower potential end for n-type, and the higher potential end for p-type microwires, in agreement with previous reports on asymmetric self-heating of microstructures. Numerical modeling of electrical and thermal transport is performed on the wires using 3-D finite element modeling. Modeling results suggest that elevated temperatures (\u3e 1300 K) give rise to significant electron-hole pair generation and strong thermal gradients (~1 K/nm) lead to substantial gradients in the generation-recombination balance. The modeled results are good agreement with the both microsecond voltage pulse and long duration AC signal experiments

ELECTROTHERMAL CHARACTERIZATION OF PHASE-CHANGE FILMS AND DEVICES

The reversible changes in the optical properties of the phase-change materials have made the rewritable optical storage possible which has revolutionized the dissemination of data since 1990s. For the last two decades, the phase-change materials have been studied extensively for its applications as nonvolatile memory elements (phase-change memory (PCM) devices). While the PCM devices were initially considered as replacements for the flash memory, today they promise a universal memory acting as the main memory and the storage unit. Here we demonstrate a simple alternative to study phase-change films and devices for further fundamental studies. The films are deposited using a single sputtering target and the devices are formed using single lithography, deposition and liftoff steps. The electrical resistivity of the films and devices are characterized in a temperature range varying from room temperature to 250 °C. Finally, microscale GST wires are amorphized by melting using self-heating and quenching