AN IMPROVED COMPACT INTEGRATED ANALYTICAL SWATCH TESTING SYSTEM

A compact swatch testing system has been developed to precisely quantify the permeation and penetration of a chemical weapons agent simulant while reducing the system footprint, improving safety and usability, enhancing automation, and maintaining measurement precision comparable to its predecessor. With the addition of a new test cell design and temperature control mechanism, the improved system demonstrated higher steady-state permeation rates and shorter breakthrough times. In comparison to the earlier prototype, the compact configuration's footprint and volume are reduced substantially, thereby allowing for use inside a 6-foot laboratory hood. A reference device for assessing test cell performance was also developed.     

A Technique for Measuring Gas Evolution Rate in Electrochemical Reactions

ABSTRACT

An apparatus is described for measuring the evolution rate of gas arising from an electrochemical or chemical reaction. The main feature of the apparatus is that the time of measurement is short and that the results are recorded electrically. Hence, both the gas evolution rate and its change can be followed, and the measurements can be automated. The apparatus can be used in corrosion testing and many electrochemical and chemical kinetics studies.     

Evaluation of Monkman-Grant parameters for type 316LN and modified 9Cr-Mo stainless steels

The Monkman-Grant (M-G) and its modified parameters were evaluated for type 316LN and modified 9Cr-Mo stainless steels prepared with minor element variations. Several sets of creep data for the two alloy systems were obtained by constant-load creep tests in 550-650°C temperature range. The M-G parameters,m, m’,C, andC’ were proposed and discussed for the two alloy systems. Them value of the M-G relation was 0.90 in type 316LN steel and 0.84 in modified 9Cr-Mo steel. Them’, value of the modified relation was 0.94 in type 316LN steel and 0.89 in 9Cr-Mo steel. Although creep fracture modes and creep properties between type 316LN and modified 9Cr-Mo steels showed a basic difference, the M-G and its modified relations demonstrated linearity quite well. Them’ of modified relation almost overlapped regardless of the creep testing conditions and chemical variations in the two alloy systems, and the parameterm’ was closer to unity than that of the M-G relation.     

Optical determination of carbon dioxide and oxygen by a fluorescent membrane to evaluate the freshness of meat products

Abstract

The present study proposes the design of a portable noninvasive optical sensor consisting of fluorescence-based sensing membrane for the purpose of evaluating the freshness of various consumable meats by measuring the dual parameters of oxygen and carbon dioxide. The sensor film is attached to the inner wall of an air-tight container integrated with opto-electronics circuits. The performance characteristics of the sensor, such as the photo-stability, response time, and cross-sensitivity, were characterized to demonstrate the effectiveness of sensing before testing actual samples. The fluorescent sensor reacts rapidly with an increase in CO₂ ranging from 700 to 3800?ppm and a decrease of oxygen between 7.5 and 7?ppm observed in a period of 8?h. The sensor shows the maximum and minimum relative error of +3.80% and –2.24% for CO₂ and +2.39% and –4.34% for O₂, respectively. The accuracy of the developed sensor was ±1.75% with high precision of 5000?±?28.2?and 7?±?0.04?ppm for CO₂ and O₂, respectively, which implies low standard deviation values. The results were comparable with a reference instrument. This simple, yet nondestructive and inexpensive system analyzes the quality of meat at domiciliary levels.     

A Robotic Filter Change System

Abstract

The filtration process constitutes the beginning of chemical analyses. This process is often cumbersome and time consuming. Filtering processes become more important, especially for the continuous and automatic analysis studies in the natural environment, since samples are likely to become polluted by natural and human effects. This study deals with a new, relatively economical, robotic filter change system. Simple stepping motors are used for this system. The PIC 16F877 microcontroller serves to control motors. The system realizes the sampling and filtration processes in a fully automated manner.     

Experimental and Computational Methods for Studying Multicomponent Equilibria. II. An Automated System for Precision emf Titrations

ABSTRACT

A potentiometric titrator designed mainly for complex formation investigations is described. The titrator is constructed from electronic building blocks, without a computer. The functioning of the titrator may be described by a rigid cyclic program with the possibility of adapting the titrator to the actual chemical system by varying a few key parameters on thumbwheel switches. Before the titration, the experimenter makes the decisions necessary. The titrator has no inherent facilities to decide whether equilibrium has been attained. Experiences gained with this titrator and the advantages over a computer-based system are discussed.     

Development of an Automated Anaerobic Biodegradability Testing Device

Abstract

The development of a low-cost device used for anaerobic biodegradability testing is described, together with its experimental validation. The equipment is based on manometric measurements of the biogas produced during the fermentation of test substances in up to seven parallel closed bioreactors. It uses separate pressure sensors and relief valves, which enable continuous measurements and avoid pressure buildup that could inhibit the biochemical reactions. A low-cost data acquisition module is used and software has been developed that is specifically suited for the end-user. The equipment has been tested and validated experimentally with a system that accounts for biohydrogen production, testing the effect of original temperature on three different pre-treated inocula, using glucose as sole source of carbon and energy. The results validate the operation of the testing equipment.     

Analytical Standards

ABSTRACT

A simple system for recovering the helium (He) gas from the gas mixtures used in the CO₂ laser is discussed. Separation of the gases CO₂, N₂ and H₂ from He gas is accomplished by various chemical and physical processes. An example, including the dimension of the system and the quantity of the chemicals needed, is given for a Molectron Corporation model T250 CO₂ gas laser, based on an hour of operation. The cost and the efficiency of the system as well as the purity of the recovered He gas are analyzed.     

Automatic Sampler Coupled with Flow Injection‐Chemiluminescence Detection to Monitor Particle/Natural Water Interactions

Abstract

An automatic sampler for natural waters under LabVIEW control is described. The sampler was integrated with an incubation system and coupled with a flow injection‐chemiluminescence detection system to study the dissolution of aerosol iron in seawater at environmentally relevant concentrations. Automated sampling of seawater was achieved using a peristaltic pump and a 10‐way distribution valve. The software allows full control of the sampler for both short (hours) and long term (days) dissolution kinetics. The environmental application of the sampler highlighted its reliability (short and extended temporal resolution), flexibility, ease of use and collection of contamination free samples.     

Pressure Jump Apparatus for the Study of Fast Reactions

ABSTRACT

Fabrication of a new pressure jump cell made entirely from Plexiglas is described. Chemical relaxation effects greater than 50 μsec can be measured when the pressure on a chemical system is suddenly released from 40 atm by means of a bursting phosphor-bronze diaphragm and the resulting conductance change is measured by a Wheatstone bridge arrangement.     

Monte Carlo Simulation of Sudden Death Bearing Testing

Monte Carlo simulations combined with sudden death testing were used to compare resultant bearing lives to the calculated bearing life and the cumulative test time and calendar time relative to sequential and censored sequential testing. A total of 30,960 virtual 50-mm bore deep-groove ball bearings were evaluated in 33 different sudden death test configurations comprising 36, 72, and 144 bearings each. Variations in both life and Weibull slope were a function of the number of bearings failed independent of the test method used and not the total number of bearings tested. Variations in L ₁₀ life as a function of number of bearings failed were similar to variations in life obtained from sequentially failed real bearings and from Monte Carlo (virtual) testing of entire populations. Reductions up to 40% in bearing test time and calendar time can be achieved by testing to failure or the L ₅₀ life and terminating all testing when the last of the predetermined bearing failures has occurred. Sudden death testing is not a more efficient method to reduce bearing test time or calendar time when compared to censored sequential testing.     

Remote Detection of Organochlorides With a Fiber Optic Based Sensor II. a Dedicated Portable Fluorimeter

ABSTRACT

A dedicated portable fluorimeter, for use with fiber optic chemical sensors (FOCS) has been designed, constructed, tested, and calibrated. This represents a major advance in the development of a FOCS system suitable for in-field use. The portable fluorimeter uses an incandescent lamp, instead of a laser, for FOCS excitation and a photodiode, in place of a photomultiplier tube for detecting the fluorescence signal. It uses an optical system which is internally connected to a unitized optical block by 600 μm core optical fibers, to minimize alignment problems and increase overall system ruggedness. The system noise is less than .1.5 mV and the long-term drift is less than ±2 mV/hour. Measurements of organochloride were made at concentrations as low as 80 parts-per-billion with a signal to noise ratio of 40:1.     

Timing Circuitry for Pulsed Laser Desorption on a Scanning Mass Spectrometer

ABSTRACT

A laser desorption chemical ionization mass spectrometer configuration has been previously reported (1). The system uses a short pulsed (40 nS) CO₂ laser interfaced to a mass spectrometer (Dupont 491) which normally acquires spectra by continuous scanning of the magnetic field. In this article, the details of the timing circuitry which enables coordination of the laser pulse, mass scanning, and data acquisition are described.     

Effect of substrate surface roughness on mechanical properties of diamond-like carbon coatings

Abstract

A plasma enhanced chemical vapour deposition (PECVD) amorphous carbon coating was deposited onto 100Cr6 steel substrates having varying degrees of surface roughness. The samples were subsequently evaluated to determine the correlation between substrate roughness and coating performance. The steel substrates were prepared before coating deposition to attain five different levels of roughness: (a) ground; (b) superfinished (SF); (c) polished to 1000 grit; (d) polished to 220 grit and (e) polished to a 1 μm diamond finish. The aim of the investigation was to determine the degree of finish required for good tribological performance and coating adhesion. The mechanical and tribological properties of the samples were assessed by nanoindentation, ramped load scratch testing, and pin on disk wear testing. Nanoindentation testing was used to determine the hardness of the samples and the relative contributions to the system hardness from the substrate and coating were separated using the model of Korsunsky et al. Nanoindentation testing showed that the coating hardness (when separated from the system hardness) was lower for the samples with the SF substrate than the others: the reasons for this are discussed in the light of Raman measurements on the fractions of diamond-like and graphite-like bonding in the coatings. Ramped load scratch testing was used to determine coating adhesion and the scratch test failure mode. With the exception of the samples with the ground substrate finish, studies of the friction coefficient plots during scratch testing showed little variation between the samples, and SEM imaging revealed a common failure mode of severe spallation at the scratch track border. The samples with the ground substrate showed differences in response between scratches parallel and perpendicular to the grinding direction, with scratches parallel to the grinding direction showing more severe spallation. The average critical load to failure, as determined by the point of first failure in the scanning electron microscope, was lower for the coatings on the SF substrate than the coatings on the 220 grit, 1000 grit and 1 micron finished substrates. The critical load to failure for the samples with ground substrates was lower than the other substrate surface finishes. Pin on disk wear testing of the samples against a steel ball revealed that the major effect of the varying substrate roughness was on the wear of the counterface, with rougher substrate finishes generally resulting in higher wear rates of the counterface, although the smoothest substrate finish, the micrometre finish, also resulted in higher wear. The sample whose substrate was superfinished gave least wear of the counterface and this was therefore the optimum finish for the samples when considering their performance in a tribological couple.     

Simulation of PID and fuzzy logic controller for integrated seat suspension of a quarter car with driver model for different road profiles

Passenger travel comfort is important while analyzing the vibration control of a quarter car model. To achieve the same, various control strategies are employed by the researchers for a 2 Degree of freedom (DOF) quarter car model. We analyzed travel comfort of the passenger by designing and simulating the PID controller and Fuzzy logic controller (FLC) for an 8 DOF quarter car with integrated seat suspension and driver model. While testing the performance of the controllers, the system was subjected to four types of road disturbance individually. The responses were compared with each other along with the passive system. The results show that FLC increases the ride quality better than the PID and passive system.

     

A Flash Photolysis Instrument With Digital Smoothing of Data Using a Fast Fourier Transform

ABSTRACT

Laser flash photolysis is a useful technique for disruption of photolabile chemical bonds. The kinetics of the subsequent reformation of such bonds can then be monitored with a suitable detection system. This technique has proven useful for following the reassociation kinetics of hemeproteins with carbon monoxide. We describe the construction of this apparatus using readily available components, along with microcomputer based signal acquisition and digital filtering of data using a fast Fourier transform. The application of this apparatus to measurement of the association of cytochrome P450 with carbon monoxide is described.     

A switchable cantilver for a chemically sensitive scanning force microscope

We describe a cantilever device for a novel ’Time-Of-Flight Scanning Force Microscope (TOF-SFM)’ concept that has the capability of chemical analysis. The cantilever device consists of a switchable cantilever (SC), a microfabricated extraction electrode, and a LEGO-type microstage, which combines two different systems. It allows quasi-simultaneous topographical and chemical imaging of a sample surface to be performed in the same way as with conventional scanning probe techniques. This is achieved by the micromachined SC with a bimorph actuator that provides a reasonable switching speed in comparison with mechanically operated switches. Secondly, a short tip-electrode distance to minimize the ions extraction voltage can be realized by LEGO-type microfabrication. The measured SC tip deflection is -100 μm at 35 mW, corresponding to an estimated heater temperature of -250°C. The maximum switching speed between the two modes is -10 msec, and the sensitivity ΔR/R of an integrated piezoresistive deflection sensor is -6.7× 10^-7/nm. The tip-electrode distance is only 10 μm. The TOF-SFM is currently integrated in an ultra-high-vacuum system to perform several measurements.     

Ultra High Pressure Tribometer for Testing CO2 Refrigerant at Chamber Pressures up to 2000 psi to Simulate Compressor Conditions

Abstract

The growing interest for using the natural refrigerant carbon dioxide (CO₂) in refrigeration and air-conditioning applications instead of HFC refrigerants, due to environmental concerns, has led to the development of an ultra high pressure tribometer (UHPT) specifically tailored for testing in CO₂ environment. The existing research on tribology related to CO₂ environment has focused on investigations at relatively low chamber pressures due to equipment restrictions. The UHPT is a unique tribometer that has been custom designed and manufactured to allow testing under CO₂ refrigerant at environmental pressures comparable to those found in compressors. A special housing, which surrounds the tribological surfaces subject to testing, is capable of withstanding chamber pressures up to 13.8 MPa (2000 psi) and can be temperature controlled from 0°C to 100°C via a thermal control system. A multi-axis strain gauge force transducer measures the applied load, frictional forces, and moments during friction testing, and computer control permits different loading profiles. Using this machine, experiments were performed at a range of pressures between 1.4 MPa (200 psi) and 6.9 MPa (1000 psi) of CO₂ refrigerant. The results suggest a slightly better tribological performance at higher pressures compared to lower pressures.     

An SEM based system for a complete characterization of latch-up in CMOS integrated circuits

An electron beam testing system was established for a complete and detailed analysis of latch-up in CMOS integrated circuits. Problems which can be studied include:

• (a) identification of latch-up current paths in steady state condition;
• (b) measurement of the local latch-up sensitivity of the various parts of the circuit;
• (c) observation of the time evolution of latch-up from the firing event to the final condition.

     

CO2-TEA,MID-INFRARED,LASER-BASED DIAL SYSTEM: FEATURING OZONE DYNAMICS DURING A “VEHICLE-FREE” DAY

ABSTRACT

Long-path ozone integrated measurements with a CO₂-laser DIAL system were performed in Madrid City during a “vehicle-free” day. The results showed a strong correlation between human activity and ozone photochemical generation. The ozone concentration follows, even quantitatively, the same trend of the overall traffic intensity as long as both UV-B radiation and NO₂ are present. An average decrease of 12.3±1.2% of the intensity of vehicle traffic during the “free-vehicle” day resulted in a lowering the ozone burden by almost 14.4±1.4%. This new type of information can stimulate the development of local models to understand the dynamic underlying urban pollution. The results, indeed, show the effectiveness of such a measure to reduce the ozone burden on human and plant health.