Integrating Sphere Attachment Research Articles

Soybean rust detection and disease severity classification by remote sensing

AbstractThe detection and monitoring of soybean rust (SBR) through remote sensing is promising because of the importance of the crop and the aspects of the disease. We evaluated the effects of different levels of SBR severity on soybean [Glycine max (L.) Merr.] leaflets reflectance aiming for the construction of a disease classification model. Leaflet reflectance was evaluated on two cultivars (susceptible and partially resistant) at four disease severity levels: healthy, low, moderate, and high. Leaflets were collected in the field and taken to the laboratory for spectral evaluation through the spectrophotometer UV 2700 coupled with Integrating Sphere Attachment ISR‐603, in the range of 270–1000 nm. The feasibility of using a collection of vegetation indices (VIs) and data dimensionality reduction through multiple factor analysis (MFA) was evaluated, and a classification model was constructed. Ten algorithms were assessed based on precision, sensibility, and accuracy parameters, using 80% of the dataset as training data and 20% as testing dataset. The visible range and red edge region contributed more significantly to the disease prediction and classification model. The MFA performed satisfactorily in the dimensionality reduction and unveiled the effect of specific wavelengths on the classification of each class. Most of the VIs studied had high correlation performance across the severity classes. Classification accuracy and precision were >70% for all models. Linear support vector machine with the collection of VIs achieved the best results. This study provides a practical path for developing a detection model to be integrated into SBR management programs.

Effect of porosity on the electrical and photoelectrical properties of textured n+ p silicon solar cells

Porous silicon layers (PSLs) were prepared by electrochemical etching with different etching current densities 10, 20 and 30mA/cm2 on the front side of n+ p Si junctions. The formed porosity was determined gravimetrically within a good range of 88.27–97%. The effect of porosity on the structure, electrical, and photoelectrical properties was investigated. Scanning electron microscope (SEM) shows the evolution of PSLs morphology through the increase in surface area due to the regular increase in porosity. The optical reflectance measurements were obtained by using a UV–vis spectrophotometer equipped with an integrating sphere attachment, which reveals that the textured cells with PS layer structures have lower reflectivity value compared to the textured cell without PS structure. The current–voltage (I–V) characteristics of Al/PS/n+ p/Al junction fabricated at etching current density of 30mA/cm2 were investigated and compared with the reference Al/n+ p/Al junction. The junction parameters such as series resistance (RS), ideality factor (n) and effective barrier height (ϕb) were determined by using different methods. Under illumination, the short-circuit current density (JSC) and the open-circuit voltage (VOC) increased from 0.35mA/cm2 to 5.3mA/cm2 and from 0.39V to 0.62V, respectively. The photosensitivity of PSLs solar cells showed a noticeable enhancement in quantum efficiency of the PS cells by increasing the porosity.

Transmission vs. Diffuse Transmission in Circular Dichroism: What to Choose for Probing Solid-State Samples?

Recent advances in equipment enabled the collection of solid-state electronic circular dichroism (ECD) spectra using the commercially available integrating sphere attachment for a regular ECD spectrometer. This accessory was designed to reduce negative factors occurring in solid-state ECD measurements, and is, thereby, very useful for recording diffuse transmittance CD (DTCD) spectra using the pellet technique. In the present article, the operating principle of the integrating sphere and utility of the DTCD method in recording solid-state ECD spectra is demonstrated. Based on illustrative examples, i.e., 10-camphorsulfonic acid ammonium, cholest-4-en-3-one, (3R,4R,5S)-oseltamivir, and (S)-linezolid, ECD solid-state measurements were performed by means of both transmission and diffusion methods and later compared. Selection of these compounds as models for comparative studies was made in view of their different chromophoric systems and the profound importance in the pharmaceutical industry. During the course of this work the benefits and limitations of the use of integrating sphere are presented. The final conclusion is that more relevant solid-state spectra can be obtained by means of the DTCD method.

Photoacoustic detection and optical spectroscopy of high-intensity focused ultrasound-induced thermal lesions in biologic tissue.

The aims of this study are: (a) to investigate the capability of photoacoustic (PA) method in detecting high-intensity focused ultrasound (HIFU) treatments in muscle tissues in vitro; and (b) to determine the optical properties of HIFU-treated and native tissues in order to assist in the interpretation of the observed contrast in PA detection of HIFU treatments. A single-element, spherically concaved HIFU transducer with a centre frequency of 1 MHz was utilized to create thermal lesions in chicken breast tissues in vitro. To investigate the detectability of HIFU treatments photoacoustically, PA detection was performed at 720 and 845 nm on seven HIFU-treated tissue samples. Within each tissue sample, PA signals were acquired from 22 locations equally divided between two regions of interest within two volumes in tissue - a HIFU-treated volume and an untreated volume. Optical spectroscopy was then carried out on 10 HIFU-treated chicken breast specimens in the wavelength range of 500-900 nm, in 1-nm increments, using a spectrophotometer with an integrating sphere attachment. The authors' optical spectroscopy raw data (total transmittance and diffuse reflectance) were used to obtain the optical absorption and reduced scattering coefficients of HIFU-induced thermal lesions and native tissues by employing the inverse adding-doubling method. The aforementioned interaction coefficients were subsequently used to calculate the effective attenuation coefficient and light penetration depth of HIFU-treated and native tissues in the wavelength range of 500-900 nm. HIFU-treated tissues produced greater PA signals than native tissues at 720 and 845 nm. At 720 nm, the averaged ratio of the peak-to-peak PA signal amplitude of HIFU-treated tissue to that of native tissue was 3.68 ± 0.25 (mean ± standard error of the mean). At 845 nm, the averaged ratio of the peak-to-peak PA signal amplitude of HIFU-treated tissue to that of native tissue was 3.75 ± 0.26 (mean ± standard error of the mean). The authors' spectroscopic investigation has shown that HIFU-treated tissues have a greater optical absorption and reduced scattering coefficients than native tissues in the wavelength range of 500-900 nm. In fact, at 720 and 845 nm, the ratio of the optical absorption coefficient of HIFU-treated tissues to that of native tissues was 1.13 and 1.17, respectively; on the other hand, the ratio of the reduced scattering coefficient of HIFU-treated tissues to that of native tissues was 13.22 and 14.67 at 720 and 845 nm, respectively. Consequently, HIFU-treated tissues have a higher effective attenuation coefficient and a lower light penetration depth than native tissues in the wavelength range 500-900 nm. Using a PA approach, HIFU-treated tissues interrogated at 720 and 845 nm optical wavelengths can be differentiated from untreated tissues. Based on the authors' spectroscopic investigation, the authors conclude that the observed PA contrast between HIFU-induced thermal lesions and untreated tissue is due, in part, to the increase in the optical absorption coefficient, the reduced scattering coefficient and, therefore, the deposited laser energy fluence in HIFU-treated tissues.

Photomorphogenesis and pigment induction in lentil seedling roots exposed to low light conditions

Although roots are normally hidden in soil, they may inadvertently be exposed to low light levels in experiments or in natural conditions through cracks or light transmittance through the soil. Light has been implicated in root morphogenesis. Thus, effects of low light conditions on lentil (Lens culinaris L. cv. Verte du Puy) root morphology and root pigmentation were studied. Lentil seedlings were grown in peat or transparent, nutrient-fortified agar at a 12-h light (PAR 240 μmol · m(-2) · s(-1)), 12-h dark cycle. Roots were exposed to low levels (≈ 1-10 μmol · m(-2) · s(-1)) of broadband white light, either directly or indirectly by aboveground light penetrating the growth medium. Control roots were grown in darkness. In situ spectroscopy was used to measure transmittance and reflectance spectra of intact root tissue by mounting the upper part of the primary root directly in a spectrophotometer equipped with an integrating sphere attachment. The transmittance and reflectance spectra were used to calculate the in situ root absorbance spectrum. Absorbance bands were found in the regions 480-500 nm and 650-680 nm, possibly due to low levels of root-localised carotenoids and chlorophylls, respectively. Low light levels (≈ 1-10 μmol · m(-2) · s(-1) ) transmitted through the growth medium significantly increased root pigment concentration and root biomass, and altered root morphology by enhancing lateral root formation and inhibiting root elongation relative to roots grown in complete darkness. The light-induced changes in root morphogenesis and pigmentation appear to be primarily due to upper root light perception.

Off-normal solar optical property measurements using an integrating sphere

Shading devices attached to windows can be used to control solar gain and hence reduce building peak load and annual energy consumption. The performance of a shading device in this regard is strongly dependent on its solar optical properties. The current study discusses a unique measurement technique that was used to obtain off-normal solar optical properties of flat shading materials. The off-normal properties were needed in order to develop solar optical property models both for shading materials and shading devices. These models provide useful input to building peak load calculation and annual energy simulation tools. Special sample holders were designed and fabricated to facilitate measurements using a commercial spectrophotometer with integrating sphere attachment. A combination of theory and companion tests were used to confirm the validity of the approach.

Functionalization of textile materials by alkoxysilane-grafted titanium dioxide

Modern materials, including textiles for specific applications, have to satisfy growing requirements. Regulations concerning man and natural environment protection against harmful substances emission, UV radiation, and electromagnetic field radiation become more and more stringent. Intensive development of nanotechnology offers great possibilities to create novel—conforming to the requirements—multifunctional materials based on textile substrates. Nanoparticles of metal oxides, e.g., titania (TiO2), belong to a group of compounds having photocatalytic properties, which are able to absorb UV radiation and provide antibacterial barrier. The aim of research works was the modification of selected textiles using nanoparticles of metal oxides. Nano-TiO2 and modified nano-TiO2 with aminosilane were applied. In the first stage, the works concerned the methodology development of such nanoparticles incorporation onto selected textile substrates. Commonly used techniques, such as padding and spraying were used as well as sol–gel coating. The evaluation of microstructure of textile fabrics covered with nanostructural titanium dioxide was performed using high-resolution SEM and TEM electron microscopes. Assessment of modified textiles pertained to the determination of protective properties against UV radiation and photocatalytic and antibacterial properties. Absorption spectra of textiles were determined using double beam type of UV–Vis Jasco V-550 with integrating sphere attachment. The same apparatus was used to determine ultraviolet protection factor (UPF) of textiles according to the standard EN 13758-1:2002. Textiles modified with nano-TiO2 demonstrated high absorption of UV radiation in a full wavelength and their good photocatalytic properties were also confirmed.

Proposal for the simultaneous measurement of light absorption and backscattering by aquatic particulates

The paper presents a new experimental method that measures light absorption and backscattering by aquatic particles, combining the innovative features of the ‘modified filter–transfer–freeze’ (FTF) and ‘transmittance–reflectance’ (T-R) techniques, namely no path-length amplification and accuratecorrection for scattering loss, respectively. This method (in short: the FTF/T-R method) measures both the transmittance and the reflectance of particles deposited on a glass slide, using a double-beam spectrophotometer equipped with an integrating-sphere attachment. The data are interpreted by an algorithm that yields both the absorption and the backscattering coefficients of the particle sample. The paper includes a summary of results of validation tests, that have been performed using samples ranging from pure phytoplankton (low light scattering) to pure detrital particles (high light scattering), as well as a detailed analysis of the experimental error. The FTF/T-R measurement is somewhat more laborious than the standard transmittance measurement of particles retained on glass fibre filters. However, it has the important asset of permitting the simultaneous determination of light absorption and backscattering and it yields more accurate absorption data in situations where the magnitude of path amplification by glass fibre filters is uncertain and light scattering by the particles is high.

Optimization of the diffuse reflectance of pigmented coatings taking into account multiple scattering

The optical properties of particulate coatings consisting of homogeneous rutile or anatase pigments randomly distributed through a polymeric binder are considered in the solar spectral range. The sizes of the pigments leading to the highest values of the effective scattering coefficients per unit length are established from a multiple scattering approach. Also, taken into account are boundary reflections of the diffuse radiation at the interfaces of the particulate coatings. Optimizations of the solar reflectance of pigmented coatings are also carried out. Fairly good agreement is found when comparing to solar reflectance values obtained from spectroscopic measurements involving an integrating sphere attachment.

A study of shading and resistive loss from the fingers of encapsulated solar cells

Optimised solar cell design is dependent on the assumed shading and resistance losses associated with front contacts. In this study, a spectrophotometer with integrating sphere attachment was used to measure the reflection from the front surface of encapsulated silver electroplated front contact solar cells. The results obtained are in good agreement with a previous study by one of the authors using a different method. The measured effective shading loss is about one third of the coverage fraction of the cell grid because of trapping of light reflected from the grid. The grid loss in 4×5 cm silver electroplated front contact solar cells was found to be similar to the predicted loss from buried grid and rear point contact solar cells operating at 30 suns concentration.

ろ紙吸光法による清流河川の推定透視度に関する研究

To conserve clean water it is important to monitor slight change of its water quality. Filter Absorbance Method is a method of filtering the river water and measuring a filter by the spectrophotometer with the integrating-sphere attachment. The Absorbance curve of the filter shows the character of particle matter in water. This method is easy, cheap, and quick to measure, moreover it is suitable for checking slight water quality change. 36 rivers, which are the best BOD in the survey of 1997 in Japan, are investigated each month from November in 1998 to January in 1999. Transparency (T) was surveyed on site and Total Absorbance (TA), which is calculated from the absorbance curve as an integral value between 400 nm to 800 nm, is measured by the spectrophotometer at an laboratory. The relation between TA and T was surveyed in the condition of 4 different filtering volume, 100 cc, 200 cc, 300 cc, and 400 cc. The relation between TA and T is expressed by the following equations.

ろ紙吸光法による利根川水系の水質評価

The FAM is a method of filtering river water and measuring a filter by the spectrophotometer with the integrating-sphere attachment. The Absorbance curve of the filter shows the character of particle matter in water. Three indices were already proposed: 1. Total Absorbance (TA), which indicates turbidity and is calculated as integrated value of absorbance curve at visible area, 2. Algae index (Al), which is an index of phytoplankton and measured as a subtraction of absorbance values from 670 nm to 750 nm, 3. Ultra Violet Absorbance Index (UVAI), which is an arra surrounded by a line and an absorbance curve between 240nm and 300nm and relates particle organic matter. This method is easy, cheap, and quick way to measure, therefore it is suitable for tracing water quality in basin. In this paper water quality in Tone river basin is evaluated by this method and conventional indices between November in 1998 and January in 1999. As a result, the correlation coefficient of Turbidity and TA is r=0.86. Chl.a has a correlation with Al and its correlation coefficient is 0.74. Trihalomethane formation potential (THMFP) has relation with UVAI and correlation coefficient is 0.84 in Tone River and 0.70 in Edo River. Water quality map in Tone river basin was made using absorbance curve measured by FAM. This map is quite visual and cheap therefore it is useful for water quality management.

A method for the experimental determination of light absorption by aquatic heterotrophic bacteria

A method has been set up for the experimental determination of the volume coefficient for light absorption in vivo by aquatic heterotrophic bacteria. The application described here is the absorption measurement of the bacterial fraction that passes through the commonly used GF/F filter and remains unaccounted for. The experimental samples were prepared by successive water nitra- tions through GF/F and 0.22 urn Millipore membranes. Light-transmission and light-reflection measurements of the filter-retained samples were performed using a dual-beam spectrophotometer equipped with an integrating sphere attachment. Sample absorption was derived from the data by a procedure that corrects for the contamination of the results due to the high degree of light scattering by the bacteria. The bacterial absorption was discriminated from fine detritus absorption by bleaching the bacterial respiratory pigments using a K^Og solution. The absorption amplification caused by multiple scattering in the filter was corrected for by an expression that was obtained experimentally. A test of the method, including error analysis, was performed on samples collected in both marine and inland waters. The relative contributions to light absorption by heterotrophic bacteria and various types of paniculate matter were also measured for a typical situation. Combining the measured volume absorption coefficients with backscattering coefficients computed by Mie theory yields a set of input data to multicomponen t optical models that is needed to assess the contribution of these heterotrophic bacteria to the radiative transfer process.

Proposal for the measurement of backward and total scattering by mineral particles suspended in water

An experimental procedure for the determination of the specific backscattering and total scattering coefficients of mineral particles suspended in water is described. The procedure combines measurements performed on samples of particles retained in glass-fiber filters and suspended in water, using a dual-beam spectrophotometer provided with an integrating-sphere attachment.

Integrating Sphere Transmissometer For Field Measurement Of Leaf Transmittance

A simple field-rated transmissometer is described for rapidly determining the normal hemispherical transmittance T(0°, 2) of leaves measured in situ in the four Landsat wavelength bands. The transmissometer requires direct solar illumination of the leaf sample. It collects the transmitted light with an integrating sphere and measures the collected light using a commercially available radiometer. The transmittances determined by the transmissometer are comparable with those measured by a laboratory spectrophotometer with an integrating sphere attachment.

Correcting remission and transmission spectra of plant tissue measured in glass cuvettes: a technique

A method for measuring transmittance and reflectance of plant material in glass cuvettes using a single-beam spectrophotometer with an integrating sphere attachment is described. This method requires extensive processing of the originally measured values as these are distorted by multiple reflections of the diffusely transmitted or reflected light. Most of the theories on light interaction with scattering materials require data processing to meet the theory's prerequisites. Therefore, the complicated evaluation does not restrict the applicability of the method. Special attention is given to the 60 degree/diffuse incidence requirement of the Kubelka-Munk theory. It is argued that the 60 degree/diffuse requirement is not essential for thick scattering layers. It is further stressed that a better knowledge of the optical properties should be of great help in many fields of biology.

A summary of the present status of flow and heat transfer in rarefied gases

Porous silicon layers (PSLs) were prepared by electrochemical etching with different etching current densities 10, 20 and 30 mA/cm2 on the front side of n+ p Si junctions. The formed porosity was determined gravimetrically within a good range of 88.27–97%. The effect of porosity on the structure, electrical, and photoelectrical properties was investigated. Scanning electron microscope (SEM) shows the evolution of PSLs morphology through the increase in surface area due to the regular increase in porosity. The optical reflectance measurements were obtained by using a UV–vis spectrophotometer equipped with an integrating sphere attachment, which reveals that the textured cells with PS layer structures have lower reflectivity value compared to the textured cell without PS structure. The current–voltage (I–V) characteristics of Al/PS/n+ p/Al junction fabricated at etching current density of 30 mA/cm2 were investigated and compared with the reference Al/n+ p/Al junction. The junction parameters such as series resistance (RS), ideality factor (n) and effective barrier height (ϕb) were determined by using different methods. Under illumination, the short-circuit current density (JSC) and the open-circuit voltage (VOC) increased from 0.35 mA/cm2 to 5.3 mA/cm2 and from 0.39 V to 0.62 V, respectively. The photosensitivity of PSLs solar cells showed a noticeable enhancement in quantum efficiency of the PS cells by increasing the porosity.