The invention relates to the measurement of the shade of a particle. The particle is illuminated with light of variable intensity and viewed against a background level of illumination. A measurement is made of the ratio of time for which the intensity of light from the particle exceeds the intensity of the background to obtain a measurement of the shade of the particle.

An aqueous reagent system for the quantitative determination of protein is disclosed. The system contains Coomassie Brilliant Blue G-250 dye, a monobasic strong acid having a pK.sub.a of less than 3 (e.g. HCl), a polybasic phosphonic acid (e.g. NTP), a water soluble, non-ionic surfactant characterized as being a block copolymer containing terminal polyethylene oxide segments separated by a polypropylene oxide segment. Preferably the system also contains a small amount of an alcohol such as metha...

The invention relates to the field of mobile computing and more specific to the problem of determining the current position of a mobile device (1). If the mobile device (1) can attach itself to (wireless) networks (4) covering a small geographic area, the mobile device (1) can determine its position by querying stationary nodes attached to the network about their location. According to the invention a transmission of position information from a stationary node (3) to a mobile device (1) is effec...

A method for determining the complexed forms of immunologically determinable prostate specific antigen (cPSA) in a blood sample, e.g., by two-site immunometric assays, in which the blood sample is treated to render free PSA (fPSA)immunologically nondetectable. A particularly preferred immunometric assay method employs three anti-PSA antibodies: an antibody that binds to both cPSA and fPSA (anti-tPSA), a second anti-tPSA antibody which is characterized by the unique property that binding to fPSA ...

A method of determining or predicting a value P.sub.x of a property (e.g. octane number) of a material X or a property of a product of a process from said material or yield of said process, which method comprises measuring the absorption D.sub.ix of said material at more than one wavelength in the region 600-2600 nm, comparing the said absorptions or a derivative thereof with absorptions D.sub.im or the derivatives thereof at the same wavelength for a number of standards S in a bank for which th...

An autocalibration system includes two loudspeakers (2, 4) spaced from three microphones (16, 18, 20). Acoustic transient pulses are emitted by each loudspeaker (2, 4) in turn and from the reception of of these pulses by each of the microphones (16, 18, 20), the time-of-flight for each pulse to each microphone may be derived. From these time-of-flight measurements are also derived the distance and angular displacement of each microphone (16, 18, 20) from a reference point (12) flanked by the lou...

A method is described for quantitative determination of mercury present in a sample (liquid or solid). The method involves converting mercury compounds to elemental mercury, removing all elemental mercury from the sample in vapor form by means of vacuum, passing the mercury vapor through a column which absorbs and captures all of the mercury vapor by converting it to a halide compound, eluting the mercury halide from the column, and colorimetrically analyzing for the amount of mercury halide col...

A method of determining a hapten which comprises: (1) contacting the sample which contains or may contain the hapten with a first binding partner which binds the hapten; (2) separating the hapten bound to the first binding partner from material which is not bound by the first binding partner; (3) contacting the hapten bound to the first binding partner with a second binding partner which binds the hapten; and (4) assaying the hapten bound to a binding partner as is described. Kits are also descr...

A method of assay for the presence of .alpha.-amylase in a sample employs a derivatized .alpha.-oligosaccharide which can be hydrolyzed by an enzyme mix including .alpha.-amylase to yield an electroactive compound, and at least one other enzyme which with .alpha.-amylase gives an enzyme mix capable of hydrolyzing the derivatized .alpha.-oligosaccharide. The sample is contacted with the derivatized .alpha.-oligosaccharide and with the other enzyme to permit hydrolysis of the derivatized .alpha.-o...

A method and kit are disclosed for recalibrating a factory-prepared relationship between concentration and expected signal R.sub.exp produced by an analyzer. The method and kit use two or three calibrators at the field to obtain an actual signal R.sub.act for the two calibrators C.sub.low and C.sub.high, for example, and these two actual signals are used to create a ratio of R.sub.actlow /R.sub.explow and R.sub.acthigh /R.sub.exphigh. The first of these is used to correct the expected signals fo...