Microchip for combining gas chromatography or capillary liquid chromatography with atmospheric pressure photoionization-mass spectrometry

We present a microfabricated nebulizer chip for combining atmospheric pressure photoionization-mass spectrometry (APPI-MS) with gas chromatography (GC) or capillary liquid chromatography (capLC). The chip consists of a silicon plate and a glass plate or two glass plates. The chip includes a sample inlet channel, auxiliary gas and dopant inlet, vaporizer channel, nozzle, and platinum heater. The sample eluted from the capLC or GC is mixed with auxiliary gas and dopant (toluene) in the heated vaporizer. The chip forms a confined jet of the sample vapor, which is photoionized as it exits the chip. The analytical performance of GC- and capLC-microchip APPI-MS was evaluated with some polycyclic aromatic hydrocarbons, amphetamines, and steroids. The GC-muAPPI-MS method provides high sensitivity down to 0.8 fmol, repeatability (RSD = 7.5-14%), and linearity (r = 0.9952-0.9987). The capLC-muAPPI-MS method shows high sensitivity down to 1 fmol, good repeatability (RSD = 3.6-8.1%), and linearity (r = 0.9989-0.9992).     

Compression algorithms that preserve basic topological features in binary-coded patterns

In this paper, some problems related to the recognition of plane, two-tone pictures (e.g. handprinted characters) are considered. It is assumed that suitable algorithms (already described) have been applied to the original picture, in order to obtain linearwise, two-tone figures. A problem that arises at this point is classifying these results in a suitable way; to this purpose, it is necessary to define and perform a set of measurements such that the results obtained by applying them to figures of the same class be the same, the possible ambiguity be minimal and the loss of information be as reduced as possible. In this paper, some algorithms are described that transform the figure into another one of the least possible dimensions, but retaining a set of basic topological and quasi-topological characteristics of the original picture. While implicitly defining a set of measurements to be performed, the “reduction” of the figure is implemented so that several figures having the same basic characteristics give the same “reduced” figure as final result. The considerable reduction of the figure's dimensions may furthermore make the recognition simpler. Several algorithms are described, and the results are compared; all are of parallel type, and therefore particularly suited for hardware implementation.     

A comparative performance study of CFC502, HCFC22 and HFC125

In the paper, the performance of HFC125 as an alternative to CFC502 and R22 is assessed under different operating conditions. Cycle characteristics, such as the thermal capacity, coefficient of performance, pressure ratio, system pressures, temperatures, and compressor power are also discussed. Results obtained after extensive detailed experimental work indicate that the performance is degraded on using HFC125, relative to that obtained with HCFC22.     

Preparation and Evaluation of Directly-Compressed Indomethacin, Indomethacin Sodium and Indomethacin Meglumine Tablets

A formula containing Compactrol, Ac-Di-Sol, Aerosil 200 and talc was used to prepare directly-compressed tablets of indomethacin and its sodium and meglumine salts. The prepared tablets were evaluated for uniformity of weight and thickness, hardness, friability and content uniformity. Each batch was then divided into two, one was coated with an opaque non-enteric film coat and evaluated for coat thickness uniformity. The dissolution rates of the uncoated and coated tablets and the effect of shelf-storage, at room temperature for 11 months, on drug contents were also studied. Indomethacin meglumine tablets showed the least relative standard deviation of weight and thickness. They exhibited acceptable uniformity of content and coat thickness, and the highest hardness-friability ratio. Also exhibited, uncoated and coated, the best in-vitro release of its drug contents and the maximal stability.     

Measurements of the suitability of large rock salt formations for radio detection of high-energy neutrinos

We have investigated the possibility that large rock salt formations might be suitable as target masses for detection of neutrinos of energies about 10 PeV and above. In neutrino interactions at these energies, the secondary electromagnetic cascade produces a coherent radio pulse well above ambient thermal noise via the Askaryan effect. We describe measurements of radio-frequency attenuation lengths and ambient thermal noise in two salt formations. Measurements in the Waste Isolation Pilot Plant, located in an evaporite salt bed in Carlsbad, NM yielded short attenuation lengths, 3–7 m over 150–300 MHz. However, measurements at United Salt's Hockley mine, located in a salt dome near Houston, Texas yielded attenuation lengths in excess of 250 m at similar frequencies. We have also analyzed early ground-penetrating radar data at Hockley mine and have found additional evidence for attenuation lengths in excess of several hundred meters at 440 MHz. We conclude that salt domes, which may individually contain several hundred cubic kilometer water-equivalent mass, provide attractive sites for next-generation high-energy neutrino detectors.     

Development of a simulation model for predicting dynamic behaviour of heat pump with nonazeotropic refrigerant mixtures

A lumped parameter model has been developed to predict the dynamic behaviour of heat pumps with nonazeotropic refrigerant mixtures. The mathematical formulation of this model is based on mass, momentum, and energy balances. Several constitutive relationships are adopted in this model to describe the different phenomena encountered in heat pump operation. In addition, the proposed model includes the consequent effect of different refrigerant flow regimes and slip between two phases. Numerical results indicate that the present model predicts fairly the heat pump dynamic response and that it compares well with experimental data.     

Physicochemical treatments of anionic surfactants wastewater: Effect on aerobic biodegradability

The effect of different physicochemical treatments on the aerobic biodegradability of an industrial wastewater resulting from a cosmetic industry has been investigated. This industrial wastewater contains 11423 and 3148mgL(-1) of chemical oxygen demand (COD) and anionic surfactants, respectively. The concentration of COD and anionic surfactants were followed throughout the diverse physicochemical treatments and biodegradation experiments. Different pretreatments of this industrial wastewater using chemical flocculation process with lime and aluminium sulphate (alum), and also advanced oxidation process (electro-coagulation (Fe and Al) and electro-Fenton) led to important COD and anionic surfactants removals. The best results were obtained using electro-Fenton process, exceeding 98 and 80% of anionic surfactants and COD removals, respectively. The biological treatment by an isolated strain Citrobacter braakii of the surfactant wastewater, as well as the pretreated wastewater by the various physicochemical processes used in this study showed that the best results were obtained with electro-Fenton pretreated wastewater. The characterization of the treated surfactant wastewater by the integrated process (electro-coagulation or electro-Fenton)-biological showed that it respects Tunisian discharge standards.     

Comprehensive ESD protection for RF inputs

We demonstrate that narrow-band tuned circuits may be used for ESD protection of RF inputs, and a figure of merit for optimization of these circuits is presented. The performance of the ESD-protected RF circuit is dependent on the quality factor of the ESD device, and various protection devices are evaluated in this work. Record-breaking human body model (HBM) protection levels, exceeding 5 kV, have been achieved without significantly degrading the RF performance at 5 GHz. Broadband circuit protection is also addressed.     

Enhancement of Return Routability Mechanism for Optimized‐NEMO Using Correspondent Firewall

Network Mobility (NEMO) handles mobility of multiple nodes in an aggregate manner as a mobile network. The standard NEMO suffers from a number of limitations, such as inefficient routing and increased handoff latency. Most previous studies attempting to solve such problems have imposed an extra signaling load and/or modified the functionalities of the main entities. In this paper, we propose a more secure and lightweight route optimization (RO) mechanism based on exploiting the firewall in performing the RO services on behalf of the correspondent nodes (CNs). The proposed mechanism provides secure communications by making an authorized decision about the mobile router (MR) home of address, MR care of address, and the complete mobile network prefixes underneath the MR. In addition, it reduces the total signaling required for NEMO handoffs, especially when the number of mobile network nodes and/or CNs is increased. Moreover, our proposed mechanism can be easily deployed without modifying the mobility protocol stack of CNs. A thorough analytical model and network simulator (Ns‐2) are used for evaluating the performance of the proposed mechanism compared with NEMO basic support protocol and state‐of‐the‐art RO schemes. Numerical and simulation results demonstrate that our proposed mechanism outperforms other RO schemes in terms of handoff latency and total signaling load on wired and wireless links.