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At least 19 recordsLinked to original sources
PubMed2002

Time course of ultraviolet-induced skin reactions evaluated by two different reflectance spectrophotometers: DermaSpectrophotometer and Minolta spectrophotometer CM-2002.

BACKGROUND: Many attempts have been made to quantify ultraviolet (UV)-induced erythema and pigmentation, but most studies have been focused on the initial changes of reaction for a few hours or days and neglected the later events. METHODS: : A time course of skin colour changes induced by fluorescent sunlamp with a broad band of UVA and UVB radiation was evaluated in 15 Korean male volunteers using two different reflectance spectrophotometers for 28 days. The results were presented by E (erythema)- and M (melanin)-index as well as values converted to the L*a*b* system recommended by the CIE (Commission Internationale de l'Eclairage). RESULTS: The mean individual typology angle of the subjects was 46.6 degrees, which indicated "light" group in constitutional skin colour category. A day after UV exposure, the L* and b* values decreased significantly, following the colour direction of persistent pigment darkening. The values went in the opposite direction persistently until after the 1st week, when maximum tanning was obtained. They then shifted toward their original positions, parallel to the constitutive melanization axis. The a* index showed a significant increase toward the mean colour of haemoglobin on day 1. It returned to its original value along the constitutive melanization axis. The E-index showed a maximum value at day 1, then returned to baseline. The value of M-index reached a peak at day 7. There was no significant difference between the two instruments, but each has its own characteristic features. CONCLUSION: These promising quantitative methods should enable us to achieve objective measurement of the dermatophysiologic changes and to evaluate the efficacy of therapeutic modalities on skin disorders without the inherent errors associated with subjective judgement. Our results provide standard data on a time course of UV-induced skin erythema and pigmentation.

Adult↗
PubMed2004

Measurement of protein-like fluorescence in river and waste water using a handheld spectrophotometer.

Protein-like fluorescence intensity in rivers increases with increasing anthropogenic DOM inputs from sewerage and farm wastes. Here, a portable luminescence spectrophotometer was used to investigate if this technology could be used to provide both field scientists with a rapid pollution monitoring tool and process control engineers with a portable waste water monitoring device, through the measurement of river and waste water tryptophan-like fluorescence from a range of rivers in NE England and from effluents from within two waste water treatment plants. The portable spectrophotometer determined that waste waters and sewerage effluents had the highest tryptophan-like fluorescence intensity, urban streams had an intermediate tryptophan-like fluorescence intensity, and the upstream river samples of good water quality the lowest tryptophan-like fluorescence intensity. Replicate samples demonstrated that fluorescence intensity is reproducible to +/- 20% for low fluorescence, 'clean' river water samples and +/- 5% for urban water and waste waters. Correlations between fluorescence measured by the portable spectrophotometer with a conventional bench machine were 0.91; (Spearman's rho, n = 143), demonstrating that the portable spectrophotometer does correlate with tryptophan-like fluorescence intensity measured using the bench spectrophotometer.

Environmental Monitoring↗
PubMed2002

[Application of AOTF in spectral analysis. 2. Application of self-constructed visible AOTF spectrophotometer].

The performances of a self-constructed visible AOTF spectrophotometer are presented. The wavelength calibration of AOTF1 and AOTF2 are performed with a didymium glass using a fourth-order polynomial curve fitting method. The absolute error of the peak position is usually less than 0.7 nm. Compared with the commercial UV1100 spectrophotometer, the scanning speed of the AOTF spectrophotometer is much more faster, but the resolution depends on the quality of AOTF. The absorption spectra and the calibration curves of copper sulfate and alizarin red obtained with AOTF1(Institute for Silicate, Shanghai China) and AOTF2 (Brimrose U.S.A) respectively are presented. Their corresponding correlation coefficients of the calibration curves are 0.9991 and 0.9990 respectively. Preliminary results show that the self-constructed AOTF spectrophotometer is feasible.

Acoustics↗
PubMedDate not supplied

Usefulness of a narrow-band reflectance spectrophotometer in evaluating effects of depigmenting treatment.

As a depigmenting treatment, combined topical applications of all-trans retinoic acid (atRA) aqueous gel and 5% hydroquinone, 7% lactic acid ointment were used for Oriental patients with hyperpigmented skin lesions such as senile lentigines and nevus spilus. A narrow-band reflectance spectrophotometer and a tristimulus colorimeter were used to evaluate objectively the intensity of pigmentation and erythema at each clinical visit. L*, a*, and b* values measured with a tristimulus colorimeter (Chroma Meter CR-300) enabled the evaluation of erythema but not pigmentation. On the other hand, the melanin and hemoglobin values measured with a narrow-band reflectance spectrophotometer (Mexameter MX-16) expressed both erythema and pigmentation well. It was revealed that, in our bleaching protocol, the narrow-band reflectance spectrophotometer was quite useful for estimating accurately the intensity of pigmentation and erythema and determining the best time point for the cessation of atRA treatment.

Administration, Topical↗
PubMed2004

A mini-rapid-scan-spectrophotometer.

The mini-rapid-scan-spectrophotometer (Mini-RSS) is a scanning single-beam spectrophotometer that has been patented. It is based on a minimum of reflections and involves exclusively mirrors as beam-deflecting components. This way stray light is minimized, which results in an excellent light-throughput, high dynamics, low cost, compactness and rigidity. The Mini-RSS has been designed as a multi-purpose instrument that allows absorption, transmission, reflection, fluorescence and luminescence measurements in a single-beam mode. Its spectral range extends from the UV and visible spectrum to the IR. This provides for the possibility to measure even optically unfavorable, highly turbid or scattering samples that would be otherwise inaccessible to investigations with commercial spectrophotometers. A miniaturized and very sensitive photomultiplier-module (PM) of high dynamics allows in the visible spectral range absorbance measurements that cover up to four OD units. The Mini-RSS is capable of scanning up to 100 spectra per second with a resolution of 12 bit and 500 points. The linear dispersion is currently 5 nm and the stray light level <0.01%.

Calibration↗
PubMed2004

A high performance micro-dual-wavelength-spectrophotometer (MDWS).

The dual wavelength spectrophotometer (DWS) has proven to be the most sensitive device to monitor minute optical absorbance changes, which are inaccessible to conventional single or double beam spectrophotometers. The typical set ups, e.g. extensively used for Ca2+ or phytochrome measurements, are huge, expensive and cumbrous. Therefore, a novel high performance micro-dual-wavelength spectrophotometer (MDWS) was developed. It is miniaturized and no moving parts such as vibrational mirrors or rotating filter wheels involved. Its specifications are superior compared to the conventional set up being capable of detecting minute optical changes (reflection, absorbance, transmittance) at particular wavelengths.

Calibration↗
PubMed2002

Evaluation of redox indicators and the use of digital scanners and spectrophotometer for quantification of microbial growth in microplates.

The growth indicators 2,3,5-triphenyltetrazolium chloride (TTC), 2-[4-iodophenyl]-3-[4-dinitrophenyl]-5-phenyltetrazolium chloride (INT), 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt (XTT), 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), and resazurin were tested for their ability to indicate bacterial growth/growth inhibition. Two reading devices were evaluated and compared, a microplate spectrophotometer and a digital flatbed scanner. The bacteria used in the study were cultivated in 96-wells microplates and readings were made after 24 h. The scanned pictures were analysed with a software developed in-house to generate numerical values. It was found that resazurin was difficult to use since it shifts between three colours. MTT and TTC had a high correlation between the spectrophotometer data and the data from the scanned images. The reproducibility was similar for both reading devices. In no case was there a need to resuspend the pellets before reading. Both the XTT and INT showed lower correlations. It is concluded that bacterial growth/growth inhibition can be easily and reproducibly measured from microplate cultivations with a flatbed scanner or with a microplate spectrophotometer.

Bacteria↗
PubMed1996

Characterization of an erbium-doped fiber amplifier as a light source and development of a near-infrared spectrophotometer based on the EDFA and an acoustooptic tunable filter.

A novel light source for the near-infrared region which has the highest intensity and widest spectral bandwidth of all near-IR light sources has been developed. The system is based on a single-mode fiber (about 18 m long) doped with Er3+ ion. The doped ion produces amplified spontaneous emission (ASE) in the near-IR region (from 1500 to 1600 nm) when it is excited by a diode laser at 980 nm. Because the diode laser is fusion-spliced directly to the doped fiber, the system is compact, all-solid-state, reliable, and stable and requires little maintenance. Its ASE output intensity was found to be comparable with those of diode lasers currently available for this near-IR region and is much higher than those of conventional halogen-tungsten lamps and the so-called (high-intensity) superluminescent light emitting diodes (SLEDs). Its spectral bandwidth is, however, much wider than those of the diode lasers and the SLEDs. Even higher intensity can be obtained from the doped fiber when a low-intensity (1 mW) light from a 1550-nm laser diode is introduced into the doped fiber. The intensity is enhanced (up to 7 times compared to the ASE) because the input light is amplified by the doped fiber. Furthermore, the output intensity of this erbium-doped fiber amplifier (EDFA) can be appropriately adjusted to provide relatively higher output intensity at any range of wavelengths (within this 1500-1600-nm region) by simply changing the temperature and/or the driven current of the input diode laser. Subsequently, an acoustooptic tunable filter was used to provide a means to spectrally tune the EDFA rapidly and to develop an all-solid-state, compact near-IR spectrophotometer which not only is very sensitive, stable, and reliable but also has a very high throughput. This spectrophotometer can detect water in ethanol at a limit of detection of 10 ppm. More importantly, the high through-put makes it possible to use the instrument to measure spectra of highly absorbing samples (e.g., absorption spectrum of 1.0 M Pr3+ aqueous solution through four sheets of paper); measurements which are currently not possible with halogen-tungsten lamp-based spectrophotometers.

Amplifiers, Electronic↗
PubMed2001

A portable, non-focusing optics spectrophotometer (NoFOSpec) for measurements of steady-state absorbance changes in intact plants.

Kinetically-resolved absorbance measurements during extended, or steady-state illumination are typically hindered by large, light-induced changes in the light-scattering properties of the material. In this work, a new type of portable spectrophotometer, the Non-Focusing Optical Spectrophotometer (NoFOSpec), is introduced, which reduces interference from light-scattering changes and is in a form suitable for fieldwork. The instrument employs a non-focusing optical component, called a compound parabolic concentrator (CPC), to simultaneously concentrate and homogeneously diffuse measuring and actinic light (from light-emitting diode sources) onto the leaf sample. Light passing through the sample is then collected and processed using a subsequent series of CPCs leading to a photodiode detector. The instrument is designed to be compact, lightweight and rugged for field work. The pulsed measuring beam allows for high sensitivity (typically < 100 ppm noise) and time resolution ( approximately 10 mus) measurements in the visible and near infrared spectral regions. These attributes allow high-resolution measurements of signals associated with energization of the thylakoid membrane (the electrochromic shifting of carotenoid pigments), as well as electron transfer, e.g., the 820-nm changes associated with electron transfer through Photosystem I (PS I). In addition, the instrument can be used as a kinetic fluorimeter, e.g., to measure saturation-pulse fluorescence changes indicative of Photosystem II (PS II) quantum efficiency. The instrument is demonstrated by estimating electron and proton fluxes through the photosynthetic apparatus in an intact tobacco leaf, using respectively the saturation-pulse fluorescence changes and dark-interval relaxation kinetics (DIRK) of the electrochromic shift. A linear relationship was found, confirming our earlier results with the laboratory-based diffused-optics flash spectrophotometer, indicating a constant H(+)/e(-) stoichiometry for linear electron transfer, and suggesting that cyclic electron flow around PS I is either negligible or proportional to linear electron flow. This type of measurement should be useful under field conditions for estimating the extent of PS I cyclic electron transfer, which is proposed to operate under stressed conditions.

Journal Article↗
PubMed1996

Quantitative evaluation of passive cutaneous anaphylaxis (PCA) using a hand-held spectrophotometer.

A hand-held spectrophotometer was used for the quantitative evaluation of PCA caused by anti-TNP-IgE and TNP-BSA. A good relationship existed between the dilution of sera and the value of delta E*ab (a numerical expression of color) obtained by a hand-held spectrophotometer. In addition, the value of delta E*ab and the amount of Evans blue measured by the conventional colorimetric method correlated well. Because the method using a hand-held spectrophotometer provides a simple and objective analysis, it appears that the method is suitable as a substitute for the conventional method, which is time-consuming and requires killing animals cruelly.

Animals↗
PubMed1998

[New application of atomic absorption spectrophotometer in testing technology].

A simple and satisfactory method is developed for the new application of AAS. We can just rely on atomic absorption spectrophotometer without flame on place of UV-Visible spectrophotometer. The operation is very simple, and it can raise the efficiency of AAS. This experiment offers a possibility to find new applications of atomic absorption spectrophotometer.

English Abstract↗
PubMed2005

[Study of reference material for excitation spectrum wavelength calibration of fluorescence spectrophotometer].

A reference material used for wavelength calibration of fluorescence spectrophotometer was found. The holmium doped oxide reference material GBW(E) 130112 is a kind of standard reference material for absorption spectrophotometer. It can emit 547.7 nm fluorescence when excited by xenon lamp light. The excitation spectrum of 547.7 nm fluorescence was measured. It was found that the measured peaks of excitation spectrum are positioned at 333.56, 360.43 and 418.39 nm, respectively, which are coincident with the true values 333.8, 360.9 and 418.5 nm of reference material certification. It was illustrated that the holmium doped oxide reference material GBW(E)130112 could be used as reference material for the excitation wavelength calibration of the fluorescence spectrophotometer. Its property could be enhanced very much if high luminescent efficiency material is selected as rare earth ion doped matrix, and the purity is enhanced to reduce the cross relaxation.

Algorithms↗
PubMed2006

[Design of a portable UV-Vis spectrophotometer].

In the present paper, a method for how to design a portable UV-Vis spectrophotometer is introduced. The Hamamatsu multichannel detector S3904-1024Q and a flat field concave grating are employed to design a miniaturized dispersion system. In order to solve the contradiction between the spectral width and energy-utilizing ratio of the light source, a multi-band optical fiber is employed, one side of which is arranged to be rectangle as the entrance slit. The touch screen is employed as the input and output system of the spectrophotometer, and the miniaturized fiber-optic UV-Vis light source is employed as the light source. The research results and testing results of the prototype show that the new spectrophotometer based on the authors' new method is of miniaturization in volume(190 mm x 170 mm x 100 mm), can realize multi-wavelength-detection on-line, and is easily handled (touch screen control), and its performance accords with the Chinese national standard.

English Abstract↗
PubMed1996

Simple 13C-urea breath test with infra-red spectrophotometer.

When mass spectrophotometric analysis is used for the 13C-urea breath test to assess H. pylori infection, it is costly, complicated, and time-consuming. To overcome these disadvantages, we utilized an infra-red spectrophotometer as a substitute for the mass spectrophotometer. A total of 153 patients (181 tests) analyzed with peptic ulcers or non-ulcer dyspepsia were investigated. Breath samples were collected 15 min after ingestion of 13C-urea (100 mg in 30 ml water). An infra-red spectrophotometer was used to determine the concentration of 13CO2 in the expirate. The 13CO2/12CO2 ratio was also measured by mass spectrophotometry to compare results with those of infra-red spectrophotometric analysis. Direct detection of H. pylori was qualified in biopsy specimens. Of the 181 biopsies, 138 were positive for H. pylori infection and 43 were negative. With the urea breath test, the mean value in the positive group was significantly higher than that in the negative group (0.062 +/- 0.044 vs 0.011 +/- 0.014, respectively). The cut-off level, 0.01, was determined as delta 13C atom %. The sensitivity of infra-red spectrophotometry was 97.8% (135/138) and specificity was 74.4% (32/43). There was an extremely high coefficient of correlation (r = 0.996) between mass and infra-red photometric analysis. Infra-red spectrometry appears to have great potential not only for diagnosing H. pylori infection but also for assessing treatment results. Its advantages include technical simplicity, cost-effectiveness, and high accuracy.

Breath Tests↗
PubMed1979

Use of a spectrophotometer for radiographic photodensitometry of bone.

A conventional spectrophotometer was used to do radiographic photodensitometry of bone mass. An experiment to produce osteoporosis in guinea pigs required quantification of changes in bone mass. Lack of a densitometer necessitated finding another method for quantification. The method developed involved using industrial film in a closed X-ray system. Optical density of X-rays was then read in a spectrophotometer at nine femur locations. Highly significant correlations between optical density and femur calcium content and femur dry weight per millimeter were obtained. Histological sections from an animal with low optical density measurements confirmed bone loss by showing decreased cortical width and loss of trabecular bone. In addition to using readily available equipment, this method offers the advantage of being able to detect bone loss in specific areas of the bones. In addition, bones are left intact and can be used for other purposes.

Absorptiometry, Photon↗
PubMed2006

Study on chromium (VI) reduction kinetics by Pseudomonas aeruginosa using a combined system of acoustic wave impedance analyzer and UV-vis spectrophotometer.

A novel system combining acoustic wave impedance (AWI) analyzer with UV-vis spectrophotometer was developed for the study of chromium (VI) reduction kinetics by Pseudomonas aeruginosa. AWI gave information about the growth of Pseudomonas aeruginosa, and UV-vis spectrophotometer gave information about the concentration of chromium (VI) simultaneously. A combined system response model, for chromium (VI) reduction kinetics at lower initial chromium (VI) concentrations, was derived and proved based on the novel system. Taking into account the effect of bacterial growth on chromium (VI) reduction, the new model successfully simulated chromium (VI) bioremediation process. By fitting chromium (VI) reduction data toward the derived model, the kinetic parameters related to the process were obtained. When the concentration of peptone was 10 g L(-1), the half-velocity reduction rate constant K (C) and the maximum specific chromium (VI) reduction rate constant nu(max) were 0.7682 mg chromium (VI) L(-1) and 2.5814 x 10(-12) mg chromium (VI) cells(-1) h(-1), respectively. It was found that the combined system can provide real-time, reliable, and two-dimensional kinetic information, and can be applied to study other biological processes.

Algorithms↗
PubMed2006

New multichannel kinetic spectrophotometer-fluorimeter with pulsed measuring beam for photosynthesis research.

A multichannel kinetic spectrophotometer-fluorimeter with pulsed measuring beam and differential optics has been constructed for measurements of light-induced absorbance and fluorescence yield changes in isolated chlorophyll-proteins, thylakoids and intact cells including algae and photosynthetic bacteria. The measuring beam, provided by a short (2 micros) pulse from a xenon flash lamp, is divided into a sample and reference channel by a broad band beam splitter. The spectrum in each channel is analyzed separately by a photodiode array. The use of flash measuring beam and differential detection yields high signal-to-noise ratio (noise level of 2 x 10(-4) in absorbance units per single flash) with negligible actinic effect. The instrument covers a spectral range between 300 and 1050 nm with a spectral resolution of 2.1, 6.4 or 12.8 nm dependent on the type of grating used. The optical design of the instrument enables measuring of the difference spectra during an actinic irradiation of samples with continuous light and/or saturation flashes. The time resolution of the spectrophotometer is limited by the length of Xe flash lamp pulses to 2 micros.

Fluorometry↗
PubMed1984

An inexpensive computerized enzyme kinetics system based on a Gilford spectrophotometer and an Apple IIe microcomputer.

A microcomputer-controlled data acquisition system for spectrophotometric enzyme kinetics measurements has been assembled. The system uses an Apple IIe computer which is interfaced to the binary coded decimal output of a Gilford spectrophotometer. No analog-to-digital converter had to be purchased. A BASIC program which collects timed absorbance readings every 500 ms, plots the data in real time, performs a linear regression of the data to measure the reaction rate, and calculates the enzyme activity concentration is given in full. Details describing the interfacing of the computer to the spectrophotometer are presented which will permit other laboratories to readily assemble their own systems using this hardware. Kinetic data acquired by the system are highly reproducible and agree well with data processed much more slowly by manual techniques from strip chart recordings.

Autoanalysis↗