Ratio Of Light Intensity Research Articles

Distribution of bacteriochlorophyll between the pigment-protein complexes of the sulfur photosynthetic bacterium Allochromatium minutissimum depending on light intensity at different temperatures

Variation of the distribution of bacteriochlorophyll a (BChl a) between external antenna (LH2) and core complexes (LHl + RC) of the photosynthetic membrane of the sulfur bacterium Allochromatium minutissimum was studied at light intensities of 5 and 90 Wt/m2 in the temperature range of 12-43 degrees C. The increase of light intensity was shown to result in a 1.5- to 2-times increase of a photosynthetic unit (PSU). PSU sizes pass through a maximum depending on growth temperature, and the increase of light intensity (5 and 90 Wt/m2) results in a shift of the maximal PSU size to higher temperatures (15 and 20 degrees C, respectively). In the narrow temperature interval of approximately 14-17 degrees C, the ratio of light intensity to PSU size is typical of phototrophs: lower light intensity corresponds to larger PSU size. The pattern of PSU size change depending on light intensity was shown to differ at extreme growth temperatures (12 degrees C and over 35 degrees C). The comparison of Alc. minutissimum PSU size with the data on Rhodobacter capsulatus and Rhodopseudomonas palustris by measuring the effective optical absorption cross-section for the reaction of photoinhibition of respiration shows a two to four times greater size of light-harvesting antenna for Alc. minutissimum, which seems to correspond to the maximum possible limit for purple bacteria.

归一化光强与衰减全内反射系数的关系研究

Attenuated total reflection (ATR) ratio is usually utilized to study the properties of surface plasmon resonance (SPR) sensors. The relationship between normalized light intensity and ATR ratio is investigated, and a modification coefficient is put forward to describe the relationship. A mathematical expression is built up for the coefficient based on Fresnel principle. The result shows that the ATR ratio, which cannot be measured directly in experiments, can be determined with the coefficient and the normalized intensity of light. The characteristic of the coefficient is also discussed.

Three-color mixing for classifying agricultural products for safety and quality

A three-color mixing application for food safety inspection is presented. It is shown that the chromaticness of the visual signal resulting from the three-color mixing achieved through our device is directly related to the three-band ratio of light intensity at three selected wavebands. An optical visual device using three-color mixing to implement the three-band ratio criterion is presented. Inspection through human vision assisted by an optical device that implements the three-band ratio criterion would offer flexibility and significant cost savings as compared to inspection with a multispectral machine vision system that implements the same criterion. Example applications of this optical three-color mixing technique are given for the inspection of chicken carcasses with various diseases and for apples with fecal contamination. With proper selection of the three narrow wavebands, discrimination by chromaticness that has a direct relation with the three-band ratio can work very well. In particular, compared with the previously presented two-color mixing application, the conditions of chicken carcasses were more easily identified using the three-color mixing application. The novel three-color mixing technique for visual inspection can be implemented on visual devices for a variety of applications, ranging from target detection to food safety inspection.

(669): Regulation of vascular permeability via Mu receptors

Hemorrhage is associated with an increase in permeability resulting in decreased preload and increased tissue edema. Morphine sulfate is frequently administered as an analgesic or anxiolytic in multi-injured patients. Morphine binds to the Mu receptors located on the surface of endothelial cells and could theoretically augment the hyperpermeable state by histamine release. A recent study from our laboratory demonstrated that morphine inhibited the anticipated increase of vascular permeability in endothelial cells following hemorrhagic shock in rats. The aim of this study is to identify the pathway whereby this inhibition occurs. It is hypothesized that adenylate cyclase is upregulated through Mu receptor activation that inhibits the phosphoinositol/MAP kinase hyperpermeability cascade following hemmorhagic shock. Pilot studies were conducted in urethrane anesthetized Sprague Dawley rats. Initial studies determined the ED50 and LD50 for adenylate cyclase inhibitor (ACI) (sq22536). Six urethrane anesthetized Sprague Dawley rats were instrumented and permitted to recover for 15 minutes. Fluorescein isothiocyanate-bovine albumin (FITC-albumin), 50mg/kg, was administered intravenously after which baseline intra- and extralumenal fluorescent light intensity was measured in mesenteric postcapillary venules of transilluminated segments of small intestine. ACI, 100 mcg/kg, was subsequently administered and identical mesenteric postcapillary venules were examined to quantitate changes in permeability. The fluorescent light intensity emitted from the FITC-albumin was recorded at baseline and at 5-minute intervals for four measures and 10-minute intervals for 120 minutes after ACI administration. These images were downloaded to a computerized image analysis program that quantitates changes in light intensity. The ratio of intralumenal: extralumenal light intensity represents changes in vascular permeability. In the absence of shock, ACI administration resulted in significant decrease in light intensity ratio representing profound increase in permeability. Preliminary data suggest that this increase is attenuated by morphine administration supporting the hypothesis that morphine inhibits the phosphoinositol/MAP kinase hyperpermeability via adenylate cyclase activation. Hemorrhage is associated with an increase in permeability resulting in decreased preload and increased tissue edema. Morphine sulfate is frequently administered as an analgesic or anxiolytic in multi-injured patients. Morphine binds to the Mu receptors located on the surface of endothelial cells and could theoretically augment the hyperpermeable state by histamine release. A recent study from our laboratory demonstrated that morphine inhibited the anticipated increase of vascular permeability in endothelial cells following hemorrhagic shock in rats. The aim of this study is to identify the pathway whereby this inhibition occurs. It is hypothesized that adenylate cyclase is upregulated through Mu receptor activation that inhibits the phosphoinositol/MAP kinase hyperpermeability cascade following hemmorhagic shock. Pilot studies were conducted in urethrane anesthetized Sprague Dawley rats. Initial studies determined the ED50 and LD50 for adenylate cyclase inhibitor (ACI) (sq22536). Six urethrane anesthetized Sprague Dawley rats were instrumented and permitted to recover for 15 minutes. Fluorescein isothiocyanate-bovine albumin (FITC-albumin), 50mg/kg, was administered intravenously after which baseline intra- and extralumenal fluorescent light intensity was measured in mesenteric postcapillary venules of transilluminated segments of small intestine. ACI, 100 mcg/kg, was subsequently administered and identical mesenteric postcapillary venules were examined to quantitate changes in permeability. The fluorescent light intensity emitted from the FITC-albumin was recorded at baseline and at 5-minute intervals for four measures and 10-minute intervals for 120 minutes after ACI administration. These images were downloaded to a computerized image analysis program that quantitates changes in light intensity. The ratio of intralumenal: extralumenal light intensity represents changes in vascular permeability. In the absence of shock, ACI administration resulted in significant decrease in light intensity ratio representing profound increase in permeability. Preliminary data suggest that this increase is attenuated by morphine administration supporting the hypothesis that morphine inhibits the phosphoinositol/MAP kinase hyperpermeability via adenylate cyclase activation.

Two-color mixing for classifying agricultural products for safety and quality

We show that the chromaticness of the visual signal that results from the two-color mixing achieved through an optically enhanced binocular device is directly related to the band ratio of light intensity at the two selected wavebands. A technique that implements the band-ratio criterion in a visual device by using two-color mixing is presented here. The device will allow inspectors to identify targets visually in accordance with a two-wavelength band ratio. It is a method of inspection by human vision assisted by an optical device, which offers greater flexibility and better cost savings than a multispectral machine vision system that implements the band-ratio criterion. With proper selection of the two narrow wavebands, discrimination by chromaticness that is directly related to the band ratio can work well. An example application of this technique for the inspection of carcasses chickens of afficted with various diseases is given. An optimal pair of wavelengths of 454 and 578 nm was selected to optimize differences in saturation and hue in CIE LUV color space among different types of target. Another example application, for the detection of chilling injury in cucumbers, is given, here the selected wavelength pair was 504 and 652 nm. The novel two-color mixing technique for visual inspection can be included in visual devices for various applications, ranging from target detection to food safety inspection.

An in line non-invasive optical system to monitor pH in cell and tissue culture

pH is an important control parameter for maintenance of cell viability and for improving tissue functions during cell and tissue culture. pH monitoring during cell/tissue culture also provides valuable information on cell metabolic processes and living environment. In this study, an on-line, non-invasive pH monitoring system was developed for use during tissue/cell culture in a perfusion system, using an optical method. This device included light sources, light detectors, light guides and a flow cell. Phenol red was used as a pH indicator dye, and the ratio of light intensities at two wavelengths was measured at the same pH value. Low solution volume as low as around 10 μl could be used to detect pH. Compared to the conventional optical methods, this non-contact optical measurement can avoid the contamination of the tip of optical fibre during the long-term monitoring. It provides a possibility to do on-line monitoring and apply feed back control to maintain the culture environment at the desired conditions required for long-term cell/tissue culture.

Characteristics of Two-Dimensional Array-Type Barrier Microdischarges Operating at High Pressures of Inert Gases

The characteristics of barrier microdischarges in a two-dimensional array have been investigated under pressures of inert gases less than 18 atm. A stable discharge is obtained and vacuum ultraviolet (VUV) light emissions radiating from excimers are detected in the entire range of pressures with various scales of microdischarge. VUV light intensity is linearly proportional to an externally applied voltage. The intensity also linearly increases with pressure less than apporoximately 5 atm and gradually decreases with increasing pressure. The pressure giving a maximum intensity, pm, increases with decreasing microhole diameter of discharge. The ratio of VUV light intensity to electric input energy of discharge increases linearly with pressure up to pm.

Applications of fiber Bragg grating sensors and high-speed interrogation techniques

We are developing several kinds of fiber Bragg grating (FBG) sensors for application in river surveillance monitoring, civil structural monitoring, aerospace health monitoring, and so on. In this paper we describe highly precise FBG sensing systems, specifically water-level sensors, as a practical example. We have achieved sensor accuracy of ± 0.1% F.S., i.e. ± 1 cm for a full measurement range of 10 m in water level. For other applications, FBG interrogation techniques are described for high-frequency vibration monitoring or acoustic emission detection. In this FBG interrogation system, optical filters based on planar lightwave circuit (PLC) technology are used to measure the wavelength of the reflected light from each FBG sensor. We discuss two types of the optical filter, a Mach–Zehnder interferometer (MZI) and an arrayed waveguide grating (AWG). The wavelength shift of the FBG sensor due to strain or temperature change is determined through direct detection of the light intensity ratio from the output ports of the optical filter. We have made a FBG interrogation unit which allows four-channel FBGs to be connected in series to measure strain in the x, y, and z directions as well as temperature. Copyright © 2005 John Wiley & Sons, Ltd.

Local mechanisms for the separation of optic flow-field components in the land crab,Cardisoma guanhumi: A role for motion parallax?

Although a number of global mechanisms have been proposed over the years that explain how crabs might separate the rotational and translational components of their optic flow field, there has been no evidence to date that local mechanisms such as motion parallax are used in this separation. We describe here a study that takes advantage of a recently developed suite of computer-generated visual stimuli that creates a three-dimensional world surrounding the crab in which we can simulate translational and rotational optic flow. We show that, while motion parallax is not the only mechanism used in flow-field separation, it does play a role in the recognition of translational optic flow fields in that, under conditions of low overall light intensity and low contrast ratio when crabs find the distinction between rotation and translation harder, smaller eye movements occur in response to translation when motion parallax cues are present than when they are absent. Thus, motion parallax is one of many cues that crabs use to separate rotational and translational optic flow by showing compensatory eye movements to only the former.

Locking of 3' ends of single-stranded DNA templates for improved Pyrosequencing performance.

In Pyrosequencing, a DNA strand complementary to a single-stranded DNA (ssDNA) template is synthesized, whereby each incorporated nucleotide yields detectable light, and the light intensity is proportional to the incorporated nucleotides. Correct data interpretation (i.e., signal-to-noise ratio of light intensities) is hampered by artifacts due to the formation of secondary structures of single-stranded templates. Critical among these is the looping back of the template's nonbiotinylated 3' end to itself In the resulting structure, the 3' end functions as a primer, the extension of which results in background signals. We present two ways of preventing the self-priming of a template's 3' end: (i) the use of a modified oligonucleotide, called blOligo, which is complementary to the template's 3' end and (ii) the extension of the template's 3' end with a ddNMP. In contrast to unprotected 3' ends of ssDNA templates, causing inconsistent results, we show that protecting the 3' end of an ssDNA template using either blOligos or ddNMP enables the correct interpretation of signals and results in reliable quantification.

Diffusion length analysis and measurement in the base region of photodiodes

An experimental technique for determining the minority carrier diffusion length in the base region of SI photodiodes described. Optical arrangement has been suggested, in which the device was operated in the photoconductive mode and its photo-response in the wavelength region near the energy gap is measured. The ratio of incident light intensity to photocurrent is a linear function of reciprocal absorption coefficient the slope of which gives L n . In addition, a nonlinear least-squares analysis is also used to determine the diffusion length. Furthermore, it has been found that L n decreases as the absorbed dose of gamma rays increases.

Kinetics studies of hybrid structure formation by controlled photopolymerization

Real-time FT-NIR spectroscopy was used to monitor the individual monomer photopolymerization kinetics within the hybrid methacrylate/vinyl ether system composed of 2-phenoxyethyl methacrylate and tri(ethylene glycol) methyl vinyl ether. Photopolymerization processing conditions, such as light intensity, photoinitiator type (both free radical and cationic) and initiator ratios and concentrations, that provide preferential direction of polymer formation based on individual monomer photopolymerization kinetics and overall conversion have been evaluated. Single source UV-light irradiation was employed to produce either single or dual-stage hybrid polymerization, validating the potential of one-step, one-pot methodology for initiating stage-curable polymerizations.

Optical Coherence Tomography用合成光源の基礎研究

We have studied on the light intensity ratio of synthesized light source (SLS) for the improvement of spatial resolution of optical coherence tomography (OCT). SLS consists of two LEDs with wavelength 691 nm, spectral width 99 nm and 882 nm, 76 nm. The small imaging interferometer also consists of plan-convex lens of focal length 6 mm and diameter 6 mm, beam splitter and reference mirror with PZT. The axial resolution was measured at 1.2 μm with the side lobe intensity 42 % on the condition of intensity ratio of 1:0.5. The irradiated power was 18 μW. This axial resolution was 57 % compared to the axial resolution using a single LED. The image of test pattern was measured using the phase shift method and two lines with the interval of 9.8 μm were clearly measured. The lateral resolution was calculated at 1.1 μm from wavelength and numerical aperture.

Calcium-independent and cAMP-dependent Modulation of Soluble Guanylyl Cyclase Activity by G Protein-coupled Receptors in Pituitary Cells

It is well established that G protein-coupled receptors stimulate nitric oxide-sensitive soluble guanylyl cyclase by increasing intracellular Ca(2+) and activating Ca(2+)-dependent nitric-oxide synthases. In pituitary cells receptors that stimulated adenylyl cyclase, growth hormone-releasing hormone, corticotropin-releasing factor, and thyrotropin-releasing hormone also stimulated calcium signaling and increased cGMP levels, whereas receptors that inhibited adenylyl cyclase, endothelin-A, and dopamine-2 also inhibited spontaneous calcium transients and decreased cGMP levels. However, receptor-controlled up- and down-regulation of cyclic nucleotide accumulation was not blocked by abolition of Ca(2+) signaling, suggesting that cAMP production affects cGMP accumulation. Agonist-induced cGMP accumulation was observed in cells incubated in the presence of various phosphodiesterase and soluble guanylyl cyclase inhibitors, confirming that G(s)-coupled receptors stimulated de novo cGMP production. Furthermore, cholera toxin (an activator of G(s)), forskolin (an activator of adenylyl cyclase), and 8-Br-cAMP (a permeable cAMP analog) mimicked the stimulatory action of G(s)-coupled receptors on cGMP production. Basal, agonist-, cholera toxin-, and forskolin-stimulated cGMP production, but not cAMP production, was significantly reduced in cells treated with H89, a protein kinase A inhibitor. These results indicate that coupling seven plasma membrane-domain receptors to an adenylyl cyclase signaling pathway provides an additional calcium-independent and cAMP-dependent mechanism for modulating soluble guanylyl cyclase activity in pituitary cells.

Photocausticization of spent Bayer liquor: a pilot-scale study

The kinetics of the photodegradation of Bayer liquor has been investigated in a semi-batch pilot plant annular photoreactor using commercial titania as the catalyst. The major toxic constituent of Bayer liquor is sodium oxalate, which is formed during alumina processing and its removal and possible rejuvenation of the caustic solution is vital to plant economics. Experiments carried out under UV irradiation (250–380 nm wavelength) over 2-h runs showed that initial solution pH, light intensity, catalyst loading and dilution ratio all have strong effects on the decomposition rate. The experimental conditions were kept such that the mass transport effects were negligible. The kinetic data suggested pseudo-first order kinetics with respect to total organic carbon (TOC) concentration. Time-on-stream increase in pH as the reaction proceeded indicated the causticization of Bayer liquor.

Double phase conjugate mirror in CdTe:Ge

Abstract The coherent oscillation in double phase conjugate mirror (DPCM) geometry at 1.064 μm with ac or dc electric field applied to CdTe:Ge sample is reported. The threshold of oscillations and the conversion efficiency are studied at different electric field, total light intensity and intensity ratio of the pump beams. The conversion efficiency up to 50% is reached with rather poor fidelity which can be improved by means of a cylindrical telescope. A new architecture of all optical interconnect is proposed. An auxiliary illumination is used to control the coupling strength of the sample, switching it either below or above the threshold of oscillation. A prototype of optical switch is built that can connect one emitter/receiver to two other emitters/receivers. A switching time less than 5 ms is achieved at the intensities of the recording and erasing beams less than 100 mW/cm 2 .

Particle size effects on an optical fiber sensor response

Optical fiber sensors based on the light backscattered by particles are widely used to measure the volume fraction of suspensions. But all the users know that particle size influences the sensor response. In this paper, this particle size effect is studied for one sensor geometry (a central emitting fiber and two crowns of receiving fibers). An electronic device gives an output voltage in terms of the ratio of light intensities collected by each crown. Experimental results obtained with several suspensions, spherical glass beads and silica particles suspended in water, are scaled on a single curve in terms of the C/d3,2 ratio. C is the volume fraction and d3,2 the Sauter mean diameter, also called volume surface diameter, characteristic of size particle distribution. This single curve is validated for various particle size distributions by calculating the sensor response with Monte Carlo simulation when the particles are spherical, weakly absorbent and their size greater than the light wavelength. So, the validity range of this curve is: 0.1≤C≤0.4 with 7 μm<d3,2<25 μm. A possible application of this result is the study of size segregation during the sedimentation of a concentrated suspension, if the concentration is measured by other means (for instance by an acoustic device).

FIBER OPTIC SENSOR RESPONSE TO LOW LEVELS OF FAT IN SKIM MILK

ABSTRACTA fiber optic transmission technique using single fibers to deliver and receive light was investigated for measuring the milkfat content of homogenized skim milk. Light transmission through skim milk for wavelengths of 400 to 1000 nm was measured using a fiber optic spectrophotometer. Transmission was measured for distances of 0.5, 1, 2, 3, 4 and 5 mm and for milk containing 0.05 to 0.21 wt% milkfat. Skim milk was centrifuged, and the resulting fractions mixed to yield samples with 5 different milkfat levels. Three optical responses were tested for correlation with milkfat content. One used a light intensity measurement at a single transmission distance of 4 mm, the second used the light intensity ratio of two wavelengths at a single transmission distance of 4 mm, and the third used six different transmission distances to determine a light extinction coefficient at a single wavelength. The calibration equations from all three methods were able to predict sample milkfat content with a RMSE of 0.008 to 0.012 wt%. Statistical analysis did not find a significant difference between the three methods. Hence, for simplicity using a single transmission distance is attractive for further sensor design.

Optimization of phase-modulated excimer-laser annealing method for growing highly-packed large-grains in Si thin-films

Optimization has been done theoretically for the phase-modulated excimer-laser annealing method to grow highly packed large grains in the Si film, where the divergence of the laser light beam plays an important role. Generalized optimum annealing conditions were given graphically as a function of the maximum-to-minimum light intensity ratio. Theoretical results were verified also experimentally by growing grains as large as 7 μm with 10 μm-pitch using a single shot of excimer-laser light pulse. It is pointed out that there is a room for improving the packing density to almost 100% by simply shortening the pitch of the phase shifters.

パルスジェット分散機構を内蔵した転動流動層造粒装置における付着性微粉体の混合特性評価

Quantitative evaluation of mixing performance of a tumbling fluidized bed granulator with an opposing pulsed jet (PJ) assembly was conducted using an optical sensor and adhesive fine powders. The effects of operating conditions on the degree of mixing were investigated in terms of the ratio of light intensity reflected from the powder mixture to that in the ultimately dispersing state, ηI. The mixing performance was compared to that of other mixers of different types from the viewpoints of the degree of mixing ηI, and the energy consumption during processing. The mixing performance was equal to or higher than that of a high speed stirring mixer. The energy consumption to attain the index ηI of 0.95 using the fluidized bed granulator with the PJ assembly was approximately 50% of that required by the high speed stirring mixer.