A system is described for the conversion of a Beckman DU spectrophotometer to automatic recording-integrated densitometry. This system has also been applied to flow spectrophotometry with a wide-range monochromatic system substituted for the filter photometer of the Technic on AutoAnalyzer. A log converter is used which changes the impulse from linear to logarithmic and feeds this to the record...

The Uster ® High Volume Instrument (HVI ®) is used in the U.S. to classify cotton, including cotton color. The cotton color parameters measured on the HVI are Rd (diffuse reflectance) and +b (yellow-ness). Comments from industry have indicated that some cotton bales appeared to have changed significantly in +b (yellowness) from their initial HVI color measurements. As a result of these reports,...

statement of problem: esthetic materials undergo some physical and mechanical changes, during their service in oral cavity. purpose: the aim of this study was the evaluation of the color and opacity stability of ideal makoo (idm) composites and compare it with tetric ceram. material and methods: fifteen disk shaped samples of each material was divided into three groups of five. different aging ...

We have investigated the ordinate scale accuracy of ambient temperature transmittance measurements made with a Fourier transform infrared (FT-IR) spectrophotometer over the wavelength range of 2-10 mum. Two approaches are used: (1) measurements of Si wafers whose index of refraction are well known from 2 to 5 mum, in which case the FT-IR result is compared with calculated values; (2) comparison...

We report bacterial growth under hypergravitational stress. Cultures of E. coli and B. subtilis were subjected to the gravitational stress (38g) and their growth curves were measured using UV-VIS spectrophotometer. Experiments were also carried out to investigate nutrient consumption under hypergravitational conditions. Our results show considerable difference between samples subjected to hyper...

The most widely used and accepted method for hemoglobin determination is the cyanmethemoglobin method. However, laboratory spectrophotometers used with this procedure are not amenable to field use. We describe the design of a portable hemoglobinometer for use with the cyanmethemoglobin method. Solid-state light sources and detectors are used, and a simple meter readout of hemoglobin is produced...

An AutoAnalyzer method has been developed in which the recently introduced reagent for iron, 3. (2.pyridyl).5,6.bis(4.phenylsulfonic acid).1,2,4.triazine (“ferrozine”), is used. With the Technicon colorimeter or Gilford 300-N spectrophotometer in use, sampling rates may be 30/h or 50/h, respectively. Sample volume is 0.8 ml, and measurements are made at 560 nm. A procedure for measuring total i...