Degradation of histamine solutions used for bronchoprovocation

STUDY OBJECTIVES: To determine optimal storage conditions for histamine diphosphate (HDP) solutions used for bronchoprovocation. DESIGN: HDP was dissolved in buffered saline solution to concentrations of 0.125 to 16 mg/mL and stored in 3-mL unit dose syringes at different temperatures for varying lengths of time, with and without protection from fluorescent light. SETTING: Dark freezer (-20 degrees C), dark refrigerator (4 degrees C), and laboratory counter top (20 degrees C) illuminated by fluorescent light (375 foot-candles). MEASUREMENTS: HDP concentrations were measured after the solutions were prepared and during storage by a high-performance liquid chromatographic assay that differentiates histamine from its break down products. RESULTS: All dilutions were sterile after preparation and contained 97 to 110% of the labeled amount of HDP. Solutions constantly exposed to fluorescent light (375 foot-candles) and room temperature (20 degrees C) contained only 20 to 37% of the initial concentrations after 7 days. The same dilutions stored at room temperature, but protected from light, contained 83 to 94% of the initial concentrations. Dilutions stored in the dark in a refrigerator (4 degrees C) retained 97% of the initial concentrations after 8 weeks, while dilutions stored in the dark freezer (-20 degrees C) were stable for 12 months. CONCLUSIONS: Exposure to fluorescent light at room temperature results in degradation of histamine solutions used for bronchoprovocation. Dilutions stored in unit dose syringes and protected from light are stable for at least 8 weeks in the refrigerator and up to 12 months frozen. Once removed from the refrigerator or freezer, the solutions should be used within 6 h or discarded.     

Iron oxide/gold nanoparticles‐decorated reduced graphene oxide nanohybrid as the thermo‐radiotherapy agent

The main focus of the current study is the fabrication of a multifunctional nanohybrid based on graphene oxide (GO)/iron oxide/gold nanoparticles (NPs) as the combinatorial cancer treatment agent. Gold and iron oxide NPs formed on the GONPs via the in situ synthesis approach. The characterisations showed that gold and iron oxide NPs formed onto the GO. Cell toxicity assessment revealed that the fabricated nanohybrid exhibited negligible toxicity against MCF‐7 cells in low doses (<50 ppm). Temperature measurement showed a time and dose‐dependent heat elevation under the interaction of the nanohybrid with the radio frequency (RF) wave. The highest temperature was recorded using 200 ppm concentration nanohybrid during 40 min exposure. The combinatorial treatments demonstrated that the maximum cell death (average of 53%) was induced with the combination of the nanohybrid with RF waves and radiotherapy (RT). The mechanistic study using the flow cytometry technique illustrated that early apoptosis was the main underlying cell death. Moreover, the dose enhancement factor of 1.63 and 2.63 were obtained from RT and RF, respectively. To sum up, the authors’ findings indicated that the prepared nanohybrid could be considered as multifunctional and combinatorial cancer therapy agents.Inspec keywords: radiation therapy, toxicology, gold, biomedical materials, nanofabrication, nanoparticles, iron compounds, cancer, nanomedicine, cellular biophysics, tumours, graphene compounds, biothermicsOther keywords: graphene oxide nanohybrid, combinatorial cancer treatment agent, cell toxicity assessment, MCF‐7 cells, dose‐dependent heat elevation, multifunctional cancer therapy agents, thermoradiotherapy agent, graphene oxide‐iron oxide‐gold nanoparticles, temperature measurement, radiofrequency wave, flow cytometry, time 40.0 min, CO‐FeO‐Au     

Miscibility and tack of blends of poly (vinylpyrrolidone)/acrylic pressure-sensitive adhesive

In this study, miscibility and tack of blends of poly (vinylpyrrolidone) (PVP)/acrylic pressure-sensitive adhesive (PSA) were evaluated. For this purpose, appropriate amounts of PVP (2–30% w/w) were added to an acrylic PSA to obtain visually homogeneous solution. The resulting solution was evenly applied on a polyethylene terephthalate (PET) film with final specific thicknesses of 10, 40, and 70 μm by using a film applicator and miscibility as well as tack values were evaluated. With the addition of 2% (w/w) PVP the tack value decreased and increased in 5% (w/w) PVP and then continuously decreased up to 30%(w/w). It was found that the tack value was related to miscibility as well as to viscosity and the free functional group such as hydroxyl group of the blend. By the morphological analysis performed through scanning electron microscopy (SEM) and also by the study of thermal analysis using the differential scanning calorimetry (DSC) behavior of blends, it was found that the two distinct phases constituted after adding 5% (w/w) of PVP. This resulted in the acrylic PSA forming the continuous phase, and by increasing the concentration of PVP a dispersed phase was developed. The dispersed phase has a higher viscosity than the continuous phase and therefore cannot wet the adherent and hence result in lowering the tack values.     

A new time-delay estimation in multipath

This paper addresses a new approach to time-delay estimation based upon the autocorrelation estimator (AE). The primary aim of this paper is to estimate time-delays in a multipath environment in absence of prior knowledge of the channel. The maximum likelihood estimator (MLE) and AE are two computational tools that are used to determine the parameters of a multipath channel. MLE requires some priori knowledge of the source signal and the channel; AE can be a blind estimator but it is more suitable for a simple propagation model (one extra path). Under the multipath assumption we prove that if the observation sequence is zero padded the performance of MLE exceeds that of AE, however, at the price of higher computational efforts. The general autocorrelator estimator (GAE), based on autocorrelation of the received signal, is introduced. The GAE is formulated as a blind estimator, and the pertinent Cramer-Rao lower bounds (CRLB) are derived. We also develop an algorithm to estimate the parameters of a multipath environment based on the new generalization. The performance of this algorithm is examined for different signal-noise scenarios. Our results show that the time-delays are estimated accurately based on the proposed algorithm.     

Nonlinear two-dimensional velocity profile inversion using timedomain data

An iterative algorithm is developed to solve the nonlinear inverse scattering problem for two-dimensional lossless dielectric inhomogeneities using time-domain scattering data. The method is based on performing Born-type iterations on a volume integral equation and, hence, successively calculating higher-order approximations to the unknown object profile. Both the full-angle and the limited-angle problems are considered. Solutions are obtained for cases where the first-order Born approximation is severely violated. Wideband time-domain scattered field measurements make it possible to use sparse data sets and thus reduce experimental complexity and computation time. Several examples are given to show the ability of this method to invert arbitrarily shaped permittivity profiles using few transmitters and receivers. The high-resolution capability of the algorithm is also demonstrated     

The Staircase to Terrorism: A Psychological Exploration.

To foster a more in-depth understanding of the psychological processes leading to terrorism, the author conceptualizes the terrorist act as the final step on a narrowing staircase. Although the vast majority of people, even when feeling deprived and unfairly treated, remain on the ground floor, some individuals climb up and are eventually recruited into terrorist organizations. These individuals believe they have no effective voice in society, are encouraged by leaders to displace aggression onto out-groups, and become socialized to see terrorist organizations as legitimate and out-group members as evil. The current policy of focusing on individuals already at the top of the staircase brings only short-term gains. The best long-term policy against terrorism is prevention, which is made possible by nourishing contextualized democracy on the ground floor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Least square and Kalman based methodsfor dynamic phasor estimation: a review

The characterization of sinusoidal signals with time varying amplitude and phase is useful and applicable for many fields. Therefore several algorithms have been suggested to estimate main aspects of these signals. Within no standard approach to test the properties of these algorithms, it seems to be helpful to discuss a large class of algorithms according to their properties. In this paper, six methods of estimating dynamic phasor have been reviewed and discussed which three of them are based on least square and others are based on Kalman filter. Taylor expansion is used as a first step and continued with least square or Kalman filter in accordance with the proposal observer of each method. The theoretical processes of these methods are briefly clarified. The characterizations have been made by some tests in time and frequency domains. The tests include amplitude step, phase step, frequency step, frequency response, total vector error, transient monitor, noise, sample number, computation time, harmonic and DC offset which build a framework to compare the different methods.     

Low-Power Symmetrical Rectifier for Passive UHF RFID Transponder

Rectifier design is one of the challenging issues in passive radio-frequency identification (RFID) systems. Differential structures are good candidates as rectifiers to their high conversion efficiencies. In this paper, a novel structure is proposed to produce symmetrical power-supply utilizing differential circuit configuration simulated in 130nm CMOS technology. The proposed rectifier can provide 1.34 V DC power with 382% voltage conversion efficiency, thus demonstrated its higher performance over existing designs.     

Ion-exchange kinetics and thermal decomposition characteristics of Fe2+-exchanged alginic acid membrane for the formation of iron oxide nanoparticles

The ion-exchange kinetics of Fe²⁺ cations in aqueous solution with H⁺ from alginic acid have been analyzed in this study as a function of contact time lengths using inductively coupled plasma-atomic emission spectrometry analysis. The kinetic parameters have been evaluated using pseudo 1st or 2nd order models, and a consistent ion-exchange mechanism is suggested. Furthermore, an insight into the calcination of Fe²⁺ ion-exchanged alginic acid process has been obtained by using simultaneous thermo-gravimetric analysis coupled with differential scanning calorimetry and high temperature X-ray diffraction.     

Using Taguchi method to determine optimum process conditions for flue gas desulfurization through an amine scrubber

This study was done to determine the optimum process conditions for absorption of sulfur dioxide in a mixture of flue gases. Using a selective amine-based absorber; a high amount of SO₂ was absorbed in the scrubbing process. The process was designed to reduce the amount of sulfur dioxide. The pilot plant was designed and set up in the Research Center of Petroleum University of Technology, containing absorption and desorption stages. This paper reports an investigation of the effect and optimization of parameters that improve the efficiency of the whole process. The experiments were conducted under varying levels of desorption temperature, pH of the absorber solution, concentration of SO₂ inlet gas, and flow rate of the absorbing solution. Using Taguchi experimental design method, the optimum conditions were identified for the absorption process. An efficiency of more than 99 % could be obtained by varying the parameters in which all the released SO₂ gas was absorbed from the inlet flue gas; an achievement that is much favorable for industrial purposes.