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Mixed electronic and ionic conductivity (MIEC) perovskite oxides hold promise as cathode with high oxygen reduction reaction (ORR) activity for solid oxide fuel cells (SOFCs) operating at reduced temperatures. However, these MIEC cathodes usually contain lanthanide or alkaline-earth elements at A-site. These elements tend to interact with yttria-stabilized zirconia electrolyte (YSZ) to form unwanted phases such as La2Zr2O7 and SrZrO3 at conventional electrode fabrication conditions (>800 °C). Such unwanted interfacial reaction severely degrades the cell performance. We present a new method to assemble SrCo0.4Fe0.5W0.1O3-δ (SCFW) directly onto YSZ by a highly efficient microwave plasma technique. Intimate contact between SCFW and YSZ phases can be achieved by ten-minute microwave-plasma treatment with no new phase formation. Consequently, the microwave-plasma fabricated interface exhibits a notably high ORR performance, showing an area-specific resistances of 0.11 Ω cm2 at 600 °C, about two orders of magnitude better than the equivalent prepared via the conventional method. Our method is also effective in assembling other MIEC perovskite cathodes such as SrCo0.5Fe0.5O3-δ and SrCo0.8Nb0.1Ta0.1O3-δ on YSZ electrolyte, achieving notable enhancement of the cathode performance. This study thus provides an effective and convenient method for synthesizing reactive and robust interfaces between two incompatible phases with minimized interphase interactions.

Granule breakage is an important rate process in wet granulation that promotes product uniformity and controls product size and strength. In this work, a model to predict granule breakage is proposed and experimentally validated. The model assumes exponential of the surviving granules, dependent on a probability of breakage; a function of powder and binder properties, as well as operating parameters. Validation experiments were performed with a breakage-only granulator, filled with cohesive, non-granulating sand. Premade pellets made from lactose monohydrate and silicone oils were granulated at several impeller speeds, and the number of survivors was observed over time. The results revealed that the number of granules did indeed decay exponentially. It was found that the overall probability of breakage was inversely proportional to the capillary number. Moreover, the pore saturation played an important role in determining the probability of breakage, with higher pore saturations reducing breakage overall. A comparison with experimental data from literature revealed that the developed models agrees qualitatively with the experimental data, but is unable to fully capture the effect of powder properties and powder-binder interaction.

Dry granulation is commonly used in the pharmaceutical industry for compressing heat and moisture sensitive feed materials into compacts, subsequently followed by milling. Population balance models (PBMs) are often used to explore the effects of milling conditions on the granule size distribution (GSD) but limited studies have investigated the effects of the feed material and ribbon properties on the resulting GSD. In this work, a variety of feed materials and ribbons with different mechanical properties were used to validate a mass-based bi-modal breakage function developed in a previous study (Olaleye et al., 2019). Ribbon like tablets (referred to as ribblets) with a range of precisely controlled porosities were produced using an Instron machine and pharmaceutical excipients including the microcrystalline cellulose MCC 101, MCC DG and a DCPA/MCC mixture. Roll compacted ribbons were also produced using MCC 102 and MCC DG excipients. The ribblets and ribbons were milled in an impact-dominated cutting mill and PBM parameters were obtained from the ribblet milling data. Mechanistic models related to the feed ribbon property were then developed. It was found that the PBM with the mass-based bi-modal breakage function can accurately predict the GSDs of both the milled ribblets and roll compacted ribbons. The model developed was successfully linked to ribbon properties such as porosity for the first time and the model parameter a that reflects the fines mode in the bi-modal breakage function increased linearly with ribblet porosity. This work demonstrates the versatility of the developed PBM and provides a systematic approach for describing the ribbon milling process.

Dry granulation through roll compaction is a technology commonly used in the pharmaceutical industry for producing roll compacted ribbons. The significance of the feed screw speed and roll speed during ribbon production was highlighted in recent publications. However, previous studies focused primarily on the individual effects of either the feed screw speed or roll speed on ribbon porosity, and the synergetic effect of these parameters was rarely examined. The aim of this study therefore was to investigate the effects of the screw-to-roll speed ratio on the porosity of roll compacted ribbons, produced at different roll compaction conditions using the microcrystalline cellulose MCC, Avicel PH-102 feed material. It was observed that ribbon porosity decreased linearly with increasing screw-to-roll speed ratio. Furthermore, an increase in the speed ratio led to an increase in the roll gap and mass throughput while a decrease in the screw constant was observed. Thus, this study demonstrates that the screw-to-roll speed ratio can be treated as one of the critical process parameters for controlling ribbon porosity and can also be used to determine the optimum operating regimes during roll compaction.

Possessing the advantages of both polymeric membranes and the specific inorganic nanoparticles or nanotubes, mixed matrix membranes (MMMs) have captured the imagination of researchers for a possible technological breakthrough for efficient gas separation. However, it is still very challenging to achieve defect-free interface between fillers and polymer matrix. In this study, the naturally abundant and low cost halloysite nanotubes (HNTs) were applied as fillers for MMMs synthesis. To improve the filler dispersion and filler-matrix interface affinity, the raw HNTs were modified by either alkali etching or (3-Aminopropyl) triethoxysilane grafting. After surface etching, the defect holes were formed on the surfaces of etched-HNTs, resulting in the rougher HNT walls and significant increment of surface area and CO2 adsorption capacity. The filler/polymer interfacial voids and filler dispersion were quantitatively assessed by tomographic focused ion beam scanning electron microscopy. HNTs surface etching significantly improved the HNTs/polymer interfacial affinity (void% = 0.06% for Raw-HNTs MMM, 0.02% for Etched HNTs MMMs) and filler dispersion, while grafted-HNTs mainly contribute to the filler dispersion. Compared to the pure polymer membrane and MMMs with untreated HNTs, MMMs containing 10 wt.% etched HNTs filler exhibited both increased CO2 permeability (807.7 Barrer) and higher CO2 selectivity (CO2/CH4 selectivity of 27.8) on the well-known limit of Robeson upper bound. In contrast, grafting HNTs only increased the membrane permeability without enhancing CO2 selectivity. The results suggest that surface etching can be an effective route in filler modification to improve interfacial morphology and membrane separation performance.

Pursuing efficient and low-cost catalysts for the sluggish oxygen evolution reaction (OER) is imperative for the large-scale deployment of promising electrochemical technologies such as water splitting and CO₂ electrochemical reduction. The earth-abundant perovskite catalysts based on LaNiO₃-δ show promise in OER catalysis because of their relatively low cost and their optimal electronic structure but suffer from low electrode-area normalized activity. In this work, we partially substituted La with Sr and Ni with Fe to enable a remarkably high OER activity with an ultra-low overpotential of 374 ± 3 mV vs RHE at a current density of 10 mA cm−2 normalized by electrode geometric area. This performance even surpasses the performance of benchmark RuO2. Our results show that Sr could promote OER-active sites including Ni(III), O2−₂/O−, and optimal Ni/Fe ratios, which significantly improve the surface intrinsic activity at the perovskite surface. Therefore, this work not only developed a highly efficient earth-abundant catalyst towards OER, but also demonstrated the effective modulation of catalyst surface interactions through A-site doping for perovskite oxides for key applications such as water splitting, CO₂ electrochemical reduction and N₂ electrochemical fixations.

The stability of agglomerated/pelletized ores is one of the key properties for successful heap leaching of complex, low-grade nickel laterite minerals. In this paper, single pellets of saprolitic and goethitic nickel laterite with controlled binder type (tap water and 44 wt.% H2SO4), binder content and pre-set porosity were made by a pellet press and subjected to mechanical strength and rewetting stability tests. The effect of fine/coarse particles ratio on the mechanical strength was also investigated using siliceous goethitic ore. The failure strength of the pellets under different drying conditions was measured and the time taken for the pellets to disintegrate under saturated (soaking) and leaching conditions was recorded. The results showed that, with the same type of nickel laterite, the time taken to disintegration during leaching test is proportional to the pellets tensile strength. Pellets with water as binder are more stable under soak conditions. Furthermore, failure strength for oven dried pellets is greater than that of air dried. With saprolitic nickel laterite (SAP) pellets, their mechanical strength and re-wetting stability can be enhanced by drying the wet pellets or by increasing the binder content in the pellets. The pellets mechanical strength was found to be a good indication of their stability under leaching conditions as well. However, no relationship between the two was observed for goethitic nickel laterite pellets. Refereed/Peer-reviewed

In this research, TiO2 nanoparticles were treated with hydrophobic 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (fluorosilane) in acidic, neutral and alkaline conditions. The treated nanoparticles were characterized using FTIR spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, transmission electron microscopy and X-ray diffraction spectroscopy. Reflectance spectra were obtained using UV–vis diffuse reflectance spectroscopy and band gap energy of the various nanoparticles was determined. Zeta potential measurements were used to evaluate colloidal stability of nanoparticles in aqueous media. The mechanism of fluorosilane adsorption on the surface of TiO2 nanoparticles was investigated using ATR-FTIR spectroscopy and turbidimetric technique. The characterization results revealed that the amorphous fluorosilane adsorbs on the surface of TiO2 nanoparticles in both neutral (pH 6) and alkaline (pH 11) solutions. The values of the band gap energy for all treated nanoparticles were almost the same, in the range of 3.10–3.18 eV. Zeta potential measurements showed that isoelectric point of the TiO2 nanoparticles shifts from 6.8 for untreated TiO2 to 4.4 for treated one. Based on the zeta potential measurement results, it is expected that treated TiO2 nanoparticles in neutral or alkaline conditions have higher colloidal stability and better dispersion in the aqueous solutions. Hydrophobic character of fluoro specious on the surface of nanoparticles leads the treated nanoparticles migrate towards the suspension surface. Therefore, these treated nanoparticles may be useful for developing self-cleaning coatings with minimal destructive effect on the polymeric matrix. Refereed/Peer-reviewed

Nickel laterite pellets with controlled mass, porosity and binder were made by using a pellet press. Both water and sulphuric acid solution were used as binders. The wet pellets were then dried at different conditions and their mechanical strength was measured. Leaching tests were also conducted on single pellet with irrigation of sulphuric acid solution from the top of the pellet. The leached out solutions were collected and nickel recoveries were analysed. The time taken for the pellets to disintegrate during leaching test was also recorded. It was found that the mechanical strength of the pellets was directly related to their dryness, with completely dried pellets having much higher strength. The dry pellet strength was found to increase with increasing binder content and decreasing pellet porosity. The time taken for the pellets to disintegrate during leaching test increased with increasing pellet strength. In comparison to sulphuric acid solution-bound pellets at the same condition, water-bound pellets exhibited higher mechanical strength. Although the nickel leaching rate for water-bound pellets was low at the beginning of the leaching test, the pellets lasted for more than 200 h without disintegration, with 70% of nickel recovered. Refereed/Peer-reviewed

In this paper, ibuprofen from a commercial source and its fractioned samples with narrower size distribution were characterized to assess the effect of particle properties on compaction characteristics. The compaction behavior of binary mixtures of ibuprofen with spray-dried lactose was also studied. The tablet in-die densification rate and tablet out-of-die porosity and tensile strength were measured for all samples. It was found that the particle size of ibuprofen does not affect the yield stress as derived from a Heckel plot, however the yield stress increases with the increase of ibuprofen particle size in the binary mixtures. Particle size also affects the tablet out-of-die properties, with tablet porosity and tensile strength increasing with the decrease in particle size. The effect of adding a weak compacting powder such as lactose on the tablet tensile strength is very much dependent on the ibuprofen particle size and mass ratio of the binary mixtures. Mixing lactose with ibuprofen of similar size in equal mass has no effect on the tensile strength of the tablet whereas mixing it with ibuprofen of larger size reduces the strength compared to ibuprofen alone. Adding a smaller amount of lactose can lead to an increase in tablet strength, even though the particle size of ibuprofen and lactose is quite different. Theoretical analysis on the tablet strength based on particle–particle bond strength was also carried out to explain the experimental results.

This study investigates the flow properties of binary mixtures of both commercial ibuprofen and reprocessed ibuprofen through high shear milling with lactose powders. Ibuprofen is recrystallized in a 30% water–ethanol mixture before high shear wet milling (HSWM). In-situ Process Analytical Techniques (PAT) (Labmax®) is used to study the HSWM process dynamics, with particle size measured by a Lasentec Focused Beam Reflectance Measurement, FBRM®. The flow properties of the binary mixtures of the different ibuprofen particles and its binary mixtures with lactose were measured using a Schulze® RST-XS ring shear tester. Results show that the morphology of ibuprofen was changed from needle to hexagonal like crystals during recrystallization and crystal size was reduced dramatically by HSWM for 1 h. The flowability of milled ibuprofen powders is reduced significantly due to its reduced size and change of surface morphology. Mixing the HSWM ibuprofen powders with lactose enhanced its flow properties. However, the increase of the mixture flowability for HSWM ibuprofen is less significant in comparison to the binary mixtures of lactose with commercial ibuprofen.

Agglomeration of fine mineral particles as a precursor to heap leaching is an important means of enhancing leaching rates and metal recoveries, particularly in processing low grade ores. In this paper, the modelling of a batch drum agglomeration process applied to nickel laterite using population balance model is explored. The coalescence kernels which are linked to feed material and agglomerator operating conditions are reviewed. The use of a physically based coalescence kernel which relates agglomerate layer thickness to binder content and agglomerate consolidation shows great promise for the modelling of the agglomerate size distribution of nickel laterite ore. The model parameters were then used to predict the effect of operating parameters such as binder content on agglomerate size distribution. Refereed/Peer-reviewed

In a previous paper, Hoornaert et al. ( Powder Technol. 96 (1998); 116-128) presented data from granulation experiments performed in a 50 L Lodige high shear mixer. In this study that same data was simulated with a population balance model. Based on an analysis of the experimental data, the granulation process was divided into three separate stages: nucleation, induction, and coalescence growth. These three stages were then simulated separately, with promising results. It is possible to derive a kernel that fit both the induction and the coalescence growth stage. Modeling the nucleation stage proved to be more challenging due to the complex mechanism of nucleus formation. From this work some recommendations are made for the improvement of this type of model.

It was previously published by the authors that granules can either coalesce through Type I (when granules coalesce by viscous dissipation in the surface liquid layer before their surfaces touch) or Type II (when granules are slowed to a halt during rebound, after their surfaces have made contact) (AIChE J. 46 (3) (2000) 529). Based on this coalescence mechanism, a new coalescence kernel for population balance modelling of granule growth is presented. The kernel is constant such that only collisions satisfying the conditions for one of the two coalescence types are successful. One constant rate is assigned to each type of coalescence and zero is for the case of rebound. As the conditions for Types I and II coalescence are dependent on granule and binder properties, the coalescence kernel is thus physically based. Simulation results of a variety of binder and granule materials show good agreement with experimental data. (C) 2002 Elsevier Science Ltd. All rights reserved.

Background: Bence Jones proteins or monoclonal immunoglobulin κ and λ free light chains (FLCs) are important markers for identifying and monitoring many patients with B-cell tumors. Automated immunoassays that measure FLCs in urine and serum have considerable clinical potential.Methods: Sheep antibodies, specific for FLCs, were prepared by immunization with pure κ and λ molecules and then adsorbed extensively against whole immunoglobulins. The antibodies were conjugated onto latex particles and used to assay κ and λ FLCs on the Beckman IMMAGETM protein analyzer.Results: The unconjugated antibodies showed minimal cross-reactivity with intact immunoglobulins or other proteins. With latex-conjugated antibodies, κ and λ FLCs could be measured in normal sera and most normal urine samples. Patients with multiple myeloma had increased concentrations of the relevant serum FLC, whereas both FLCs were increased in the sera of patients with systemic lupus erythematosus.Conclusions: We developed sensitive, automated immunoassays for κ and λ FLC measurements in serum and urine that should facilitate the assessment of patients with light chain abnormalities.

In this work coalescence of deformable granules in wet granulation processes is modelled. The model accounts for both the mechanical properties of the granules and the effect of the liquid layer at the granule surface. It is an extension to the model of Ennis ct al. (1991) to include the possibility of grannule plastic deformation during collisions. The model is written in dimensionless groups such as viscous and deformation Stokes numbers and the ratio of granule dynamic yield strength to granule Young's modulus (Y-d/E*). These variables are bulk parameters of the powder-binder mixture and also functions of the process intensify. The model glues the conditions for two types of coalescence - type I and type II. Type I coalescence occurs when granules coalesce by viscous dissipation in the surface liquid layer before their surfaces touch. Type II coalescence occurs wizen granules are slowed to a halt during rebound after their surfaces have made contact. The model explains some of the trends observed in the literature, ale pi preliminary validation of the coalescence criterion with drum granulation data is encouraging. An extension is also made to the case of surface dry granules, where liquid is squeezed to the surface during granule information.

Two steps are usually involved in producing high impact polypropylene copolymer in a continuous process. The first is to polymerize propylene using Ziegler-Natta type or more recently metallocene catalyst, and the second is to add ethylene-propylene rubber (EPR). A narrow residence time distribution (RTD) of polymer particles is an important process design and operational target in this process. The broadening of RTD will lead to a widening of copolymer composition distribution in which results in inferior product properties. There are several techniques to obtain a narrower RTD, including by controlling size of particles leaving a well-mixed reactor. In this paper, a dynamic population balance model to track polymer particle age and size is presented. The model is applied to a well-mixed slurry reactor linked to a classifier. Polymer particle growth kinetics including catalyst deactivation with particle age are incorporated. The model agrees well with steady-state analytical solutions and process data for particle age and catalyst efficiency. The classifier acts to significantly narrow particle age distribution. However, the system is very sensitive to small change in feed catalyst size, catalyst deactivation can cause build up of small polymer particles trapped in the system if the feed catalyst size is too low. As a 'soft sensor', the RTD information from the validated model provides valuable insight for operational support. Further applications include strategies of reactor control design and optimization of grade transition policy. (C) 1999 Elsevier Science Ltd. All rights reserved.

A procedure for rapid and reproducible measurement of warfarin is described. This is based on a computer-controlled sequential injection analysis (SIA) system and utilises the phenomenon of enhancement of fluorescence seen when the drug forms inclusion complexes with β-cyclodextrin in aqueous solution. Cyclodextrin and warfarin solutions are sequentially injected and mixed within seconds using the automated system and the fluorescence is then monitored immediately. The calibration curve is linear over the measured concentration range of 0.1 to 1 μg/ml (r2 0.998, n=5) with a limit of detection of 0.02 μg/ml. The measurement is fast with response time of 20 seconds, and is also reproducible with coefficient of variation at 1.5% (n=10) at a concentration of 0.5 μg/ml. Water samples spiked with warfarin were successfully measured using the method.

The widespread application of proteolytic enzymes in many industrial sectors brings considerable benefits to modern industrial manufacturing and to the quality of life for human beings. However, as the enzymes are known potent respiratory sensitising agents, there are potential risks to workers on site and to the general public off-site, if these compounds are released into the atmosphere during their manufacture and processing. To ensure adequate containment within the factory, to protect factory workers and the general public, and to comply with health and safety legislations, it is necessary to monitor airborne concentrations of the enzymes in the workplace atmosphere. At present, however, workplace monitoring of industrial enzymes can only provide exposure data for retrospective use. There is an urgent need to develop rapid and sensitive monitoring methods which provide continuous data on a near real-time basis and detect sudden release of the sensitising material. This paper reviews the existing monitoring methods for proteolytic enzymes in the industrial atmosphere and some recent developments in this important field. Possible strategies for developing integrated sampling and detecting systems for near real-time monitoring of industrial proteolytic enzymes in the manufacturing environment are discussed.

Toxic ratio TR is a valuable tool in the discrimination of excess toxicity from baseline effect. Although some authors realized that internal effect concentration or critical body residual (CBR) calculated from bioconcentration factor (BCF) should be used in the TR, the effect of BCF on the discrimination of excess toxicity from baseline effect has not been investigated. In this paper, 951 acute toxicity data to fish (LC50) and 1088 BCFs were used to investigate the relationship between TR and BCF. The results showed that some compounds identified as reactive compounds exhibit excess toxicity, but some do not. BCF is closely related to TR and can significantly affect the TR value. The real excess toxicity which is used to identify reactive chemicals from baseline should be based on the toxic ratio of internal effect concentrations, rather than on the ratio of external effect concentrations, TR. The use of LC50 alone to determine TR can result in errors in TR because toxicokinetics (as estimated by the BCF) are ignored. The foundation in the discrimination of excess toxicity from baseline effect is based on the linear relationship between log BCF and hydrophobicity expressed as log KOW. However, log BCF is not linearly related with log KOW for all the compounds. The BCFs with log KOW >7 or

In this work, a nucleation model that includes nuclei breakage/fragmentation is proposed. The model is based on the nucleation model of Hapgood and the Stokes deformation number calculated from the granule dynamic yield strength from the previously reported granule breakage work. It is proposed that breakage or fragmentation of primary nuclei from binder spray will occur if the Stokes deformation number exceeds a certain critical number. In the case where breakage occurs the model for secondary nuclei size distribution is proposed. To validate the model, the characteristics of the primary nuclei formed from nickel laterite ores with diluted sulphuric solutions as a binder were investigated. The nuclei were produced by dropping the binder solution onto a stationary powder bed. The mechanical integrity of the primary nuclei formed, the relationship between the nuclei diameter and binder drop diameter were studied. The Stokes deformation numbers for nickel laterite powders with different particle size in a lab scale drum granulator were calculated and the nuclei size distributions with different nickel laterite feed powders are predicted. Refereed/Peer-reviewed

A rapid and sensitive homogeneous assay method has been developed for the determination of subtilisin. The method employs a protein substrate labelled with two fluorescent dyes with fluorescence energy transfer (FET) characteristics. The doubly-labelled substrate was prepared by chemically coupling bovine serum albumin with lucifer yellow and rhodamine dyes. The fluorescence emission from the lucifer labels was initially quenched due to the FET to the adjacent rhodamine labels. However, upon the addition of subtilisin into the labelled substrate solution, increased fluorescence was observed as the enzyme hydrolyzed the substrate and reduced the FET effect. The rate of increase in fluorescence due to substrate hydrolysis was used to calibrate the subtilisin assay. It was linear over the range 0–150 ng of the enzyme (n=8, r2=0.985). The assay was fast with a time of 30 sec to exceed the limit of detection (LOD) signal for 60 ng of subtilisin in 600 μl. In this volume, the LOD for the enzyme was 4.2...

In this study, the bed temperature profile of a conical/plasma fluidized bed without a distributor was studied. The same reactor was also used for growing diamond by chemical vapour deposition. It was found that the fluidized bed quenches the plasma gas quite significantly. The bed temperature increases with both the plasma gas flow rate and the plasma input power. A lateral temperature difference from the centre of the bed to the wall exists due to heat loss through the wall. The temperature profiles obtained are suitable for controlling of bed quenching conditions in particle processing and synthesis. The conical/plasma fluidized bed with a distributor on top of the plasma was then applied to diamond synthesis from a gas phase using a distributor between the bed and the plasma. The deposition mainly occurred in the plasma tail flame. Both the scanning electron micrographs and Raman spectra show the existence of diamond on seed particle surfaces, but with a rather low nucleation density. The limitations of the d.c. plasma fluidized bed system are discussed and modifications to the reactor are recommended.

Ceftazidime is a β-lactam antibiotic of the cephalosporin family. In common with other β-lactam antibiotics it is a respiratory sensitiser and occupational exposure limits have been set for workers who may inhale the drug in the workplace. Polyclonal antibodies have been raised in rabbits which specifically recognise this compound. These have been purified using immunoaffinity chromatography and the resulting anti-drug antibodies used with alkaline-phosphatase labelled anti-rabbit antibodies to generate a single reagent ELISA for ceftazidime which can be used in a rapid semi-quantitative mode to screen samples from conventional filters following monitoring of worker exposure. Presence of the drug in excess of the occupational exposure limit (OEL) (3 μg of captured ceftazidime eluted into 1 ml prior to assay) results in a lack of colour at the endpoint of the assay while samples with levels less than the OEL produce a yellow colour. The ELISA can process 45 samples in duplicate in 40 min. The sensitivity of the assay is 110 pg in a 50 μl sample volume. The assay has good precision with coefficients of variation less than 10% and it exhibits insignificant interference with a range of penicillin and cephalosporin antibiotics and other compounds tested. The assay is better suited than liquid chromatography for use on site by semi-skilled operatives immediately following the monitoring period when exposure of workers above the OEL can be rapidly ascertained and action taken.

Overproduction of plasma cell-derived monoclonal free kappa or lambda immunoglobulin light chains (FLCs) is a hallmark of multiple myeloma, AL amyloidosis, and light chain deposition disease. Because these components serve as unique cellular and serologic biomarkers, their detection and quantitation has diagnostic, therapeutic, and prognostic import. In this regard, we have developed monoclonal antibodies (mAbs) that specifically recognize the kappa or lambda FLC products of all known human variable and constant region light chain genes. We now report the results of our studies that have demonstrated the capability of these reagents to measure, in a modified fluid-phase capture enzyme-linked immunosorbent assay (ELISA), serum kappa and lambda FLCs at concentrations as low as 5 and 15 ng/mL, respectively. The mAb-based ELISA has greater sensitivity and reproducibility than does the commercially available immunoturbidimetric assay that uses polyclonal anti-FLC antibodies. In addition, the mAbs can immunostain monoclonal FLC-producing plasma cells and pathologic light chain-related amyloid and nonfibrillar tissue deposits. Our anti-FLC mAbs, with their high degree of reactivity and versatility, may provide an invaluable tool in the diagnosis and management of light chain-associated disease.

Rapid, sensitive and reusable assay systems have been developed which can be used for near real-time monitoring of some protease enzymes in the workplace. The systems are based on fluorescence measurement with flow analysis using a mini-bioreactor containing a chemically immobilized fluorophore-labelled protein substrate. Protease enzymes such as subtilisin digest the fluoro-substrate and release fluorescent fragments which are detected downstream by a fluorimeter. The assay systems were optimized and used for measurement of standard solutions of protease enzymes and enzyme-spiked non-biological detergent solutions. These exhibited satisfactory performance in terms of speed, sensitivity, reproducibility and linearity. Detection is fast with response times of 4–5 min. The relationship between the enzyme (subtilisin) concentration and the observed fluorescence signal is linear within the measured range (0–20 ng for a flow injection analysis system and 0–20 ng ml−1 for a simulated air sampling open-loop system). For the latter system using a bioreactor with 0.9 ml immobilized matrix, the limit of detection at 95% confidence is 0.26 ng ml−1. The signal is reproducible with sr of 0.93% (n = 8) for continuous use over a 16 h period with repeated exposure to 2 ng ml−1 subtilisin episodes.

Protease enzymes are commonly used in industry; exposure of the workforce to these enzymes may lead to respiratory sensitization. Assays are therefore needed which can be coupled to air sampling devices to produce real-time monitoring systems which are sufficiently sensitive and rapid to provide an early warning system that indicates that the airborne concentrations of enzyme have exceeded occupational exposure limits. Current methods based on spectrophotometric end-points are too slow and insensitive for this application. An assay is reported that is based on the release of fluorescein covalently attached to porcine thyroglobulin which is itself immobilized onto glass beads in a bioreactor. Exposure of the bioreactor to the enzymes, subtilisin, trypsin, alcalase and esperase produces a fluorescent peak in a flow through cell within 3–4 min. The resulting signal is linear (r= 0.999, n= 5) over the range 2–50 ng for subtilisin and the reproducibility of the assay (sr) at 5 ng is 0.8% for this enzyme.

A simple, ultra-rapid assay method has been developed for the determination of cellulase activity. The method is based of fluorescence detection following flow injection into a mini-bioreactor containing Lucifer Yellow-labelled cellulose. Cellulase activity is determined by measuring the intensity of the fluorescent fragments released from the bioreactor after the injection of the enzyme solution. The assay is fast, with a response time of less than 30 s. The fluorescence signal obtained is reproducible (sr= 6.1%, n= 9) and linear within the measured range (1–20 µg of crude enzyme of activity 10 units per milligram; n= 5, r2= 0.997).