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To visualize the existence of micro-calcifications in mammography there are a number of ways carried out including by the magnification technique. This study evaluates the effect of magnification technique on optical density (OD) and size of the objects of the image produced on mammography. The objects used were three circular coins. Source to image distance (SID) was 65 cm, with a focal spot size of 0.1 cm, a combination of targets/filters was Mo/Mo with a filter’s thickness of 30 µm. The tube loading was 100 mAs, the tube voltage was 27 kVp, and the magnification was in the range of 1.00 - 2.00 times with an increase of 0.25. Measurement of OD and size of the objects was using an ImageJ software. The results of this study revealed that the OD value decreases proportional to the magnification. The OD values calculated on the 2x magnification were 13.74, 14.26, and 13.44% lower than 1.0 magnification (without magnification), while the resulting image will be oval in proportion to the position of the coin from the chest wall and the magnification. An implementation of the magnification method in the mammography must be carried out with caution. In addition to a benefit to larger appear of micro-calcification, it also causes a decrease in OD and distortion of objects in the image.

Waters of river Okhta and its tributary polluted with domestic wastewater were studied during several weeks of water storage at 20°C and 8°C. At sampling day, concentrations of total organic carbon in waters were close (17-24 mgTOC/L), polluted waters had difference in electric conductivity, increased concentration of total nitrogen (TN) and NH4 +. During storage, concentrations of TOC, inorganic carbon, TN, NH4 + declined, and the decline was stronger in polluted waters and at room temperature of storage. Spectra of optical density (D) of waters showed no significant qualitative difference between polluted and not polluted waters. During storage, D254 of all samples decreased up to 40% in 12 days. Polluted water had higher fluorescence intensity (I) at emission wavelengths 320-370 nm (up to 200%) and 420 nm (up to 50%). During storage of polluted water I decreased at 320, 350, 370 nm and increased at 420 nm. For pollution detection in not diluted waters at the sampling day and after 2 weeks of water storage the following parameters can be recommended: I230,350, I230,370 or I270,350 together with ratio of protein-like to humic-like fluorescence I230, 350/420 or I270, 350/420. These parameters can be used with or without correction of I for D.

Biomass concentration is an important indicator of production rate in polyhydroxyalkanoates (PHA) fermentation process. In current practice, measurement of biomass concentration is done off-line by laboratory analysis that is unsuitable for online process monitoring and control. Soft-sensor is often used as an alternative that provides an estimate of hard to measure parameters from easy to measure process data. However, most of these studies use simulated data or data generated from mathematical model that was developed without full consideration of process and measurement uncertainty. In this study, a soft-sensor is developed from real production data for PHA fermentation in pilot-scale bioreactor with the appropriate data pre-processing techniques applied to process data that was obtained from this system. Multilayer perceptron (MLP) neural network is used to estimate biomass concentration using secondary process parameters such as dissolved oxygen (DO), temperature, pH and agitation speed as inputs. Different models are developed based on different batches of production data and various network architecture in order to study the appropriate integration of process data and network topology that gives the best model accuracy. Results indicate that the biomass soft-sensor developed using MLP-ANN provides a better estimate of biomass in comparison to radial basis function (RBF) neural network and support vector regression (SVR) methods. The developed soft-sensor can be further used in monitoring and control of production output.

The article considers the task of studying how the two processes relate - the destruction of lubricating oil and the wear of the elements of the tribosystem. The paper analyzes one of these indicators - the optical density of the oil, which characterizes the process of its destruction. The study includes the stage of constructing multifactor intelligent critical wear models depending on the optical density of the oil and the effort in the friction pair. The initial data for the construction of models are the results of measurements of the optical density of oils and the diameter of the wear spot. The obtained forecast models are indispensable for explaining the fundamental processes of wear that occur during the operation of lubricating oil. In addition to this, it should be noted that the results obtained make it possible to take the next step towards the creation of a new technique for the rapid assessment of the state of lubricating oil and the corresponding nature of the process of wear of the tribosystem.

Seahorse (Hippocampus spp.) is a species of unique marine biota showing male pregnancy. The purpose of this study was to identify seahorse species (Hippocampus spp.) through molecular approach by DNA barcoding using COI gene marker, determine the potential of seahorse as an antioxidant and an indicator of immunomodulatory properties. The research results showed the nucleotide sequences of DNA sample H1, H2, and H6 identified as H. kuda, while H3, H4, and H5 were identified as H. comes with the level of identity (homology) as much as 98%-99%. In general, the results of antioxidant activity in seahorse samples can be used as a source of natural antioxidants, namely in the form of seahorse hydrolysates and seahorse ethanol extract (IC50 50-100 ppm). The highest cell proliferation activity was from the seahorse powder group at a concentration of 250 ppm with the value of OD (Optical Density) of 0.227±0.002 and SI (Stimulant Index) of 120.74%. These results indicated that seahorses potentially have indicators of immunomodulators properties.

The paper presents the results in the field of research and analysis of the optical density of motor oil using mathematical and intelligent models. The quadratic approximations of the dependence of optical density on time are obtained for three different temperatures of temperature control. It is established that each curve of the change in optical density with time contains an inflection point. On the basis of which it was hypothesized that these moments correspond to a certain phase transition in the oil under study. A three-dimensional model of dependence of the rate of change of optical density on temperature and test time was also constructed. When analyzing this dependence, the character of the inflection curve is established, which is proposed as an indicator indicating the attainment of the limiting resource of lubricating oils.

The article discusses the physical processes in a flowing fluid that affect the change in its optical density. Changes in the refractive index and its errors in single-component and multicomponent media for different fluid flow regimes are investigated. A new model has been developed for calculating error of refractive index, considering the non-uniformity of optical density in a stream liquid. A technique is proposed for selecting a refractometer model for reliable monitoring the state of liquid environment.

The main factors responsible for measurement errors in the determining of the refractive index of the flowing fluid are considered. It was found, that the most significant effect on the measurement error have changes in optical density and temperature of the investigated flowing fluid, scattering of radiation in cuvette transducer and wedge shape of the cuvette glass. A new design of differential refractometer has been developed to study the influence of the optical density values of the flowing fluid on the measurement errors. The results of experimental studies are presented.

The results of testing motor and transmission oils for thermal-oxidative stability, including optical density and coefficient of thermal-oxidative stability, are presented. According to the results of the study, the temperature range of application of the oils was determined. The method of testing engine and transmission oils with cyclic temperature changes is presented, which allows comparing oils of the same purpose by the number of cycles of raising and lowering the test temperature, as well as identifying them for compliance with the classification according to performance properties groups.

In this study, distilers' grains were used to prepare biochar, which is renewable and ecofriendly, then cuprous oxides nanoparticles were loaded to the biochar to improve the properties of Cu2O. Their structure and morphology were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and brunauer-emmett-teller (BET) specific surface area. The results showed that the Cu2O nanoparticles were loaded onto the biochar successfully and the biochar-based Cu2O nanoparticles (Cu2O/biochar composites) have larger specific surface area than pure Cu2O nanoparticles. Their antibacterial activity against Escherichia coli (E. coli) was examined by tablet colony counting method and optical density (OD) method. The results showed that the Cu2O/biochar composites were more effective and had superior antibacterial performance than pure Cu2O nanoparticles which indicated that Cu2O/biochar composites have good application prospect in antibacterial field.

The radiochromic film, which is used, in combination with a flatbed scanner has become a widely used tool for a quantitative evaluation of radiation dose in radiation therapy. One aspect of uncertainty using the radiochromic film is the magnitude of orientation effects when the orientation of the film is not kept constant during the digitization process. The aim of this note was to investigate the impact of using a combination of two crossed sheets of EBT2 film on various aspects of radiochromic film dosimetry. First the impact on the film sensitivity was studied. We also investigated the influence on orientation effects during scanning. The results show that the double crossed film combination increases the sensitivity with a factor 1.7-2.1 and practically eliminates the effects of film orientation on the optical density read-out and the lateral correction profiles.

Interlocking compressed earth blocks (ICEB) are soil based blocks that allows for mortarless construction. This characteristic resulted to faster the process of building walls and required less skilled labor as the blocks are laid dry and lock into place. Recently, implementation in using bacteria as construction material improvement is vigorously used in research in order pursuit the sustainable construction works. This paper provide the results of ureolytic bacteria (UB) throughout enrichment process in soil condition to acclimatize the ICEB environment, compressive strength of 1%, 3% and 5% UB and SEM analysis of ICEB. The bacteria were added as partial replacement of limestone water in ICEB. The results showed the optimal growth achieved based on the days and absorbance from optical density (OD) test which are in 12th days with absorbance of 0.55 whereas the results for strength shows the increment of 15.25% with 5% UB on 28th days of testing compared to control specimen. Therefore this study hopes that positive results from the UB as improving in strength of ICEB which will lead to improve others ICEB properties and others construction materials.

The effect of dose rate on the real-time change in optical density (DeltaOD) of a GAFCHROMIC EBT film is quantified using a previously reported optical readout approach. A range of doses (5-1000 cGy) and dose rates (16-520 cGy min(-1)) are used, and a statistically significant difference between DeltaOD of films exposed at different dose rates occurs within approximately one order of magnitude change in the dose rate. A small increase in per cent standard deviation of measured DeltaOD values is also observed when the entire dose rate range was used, but in all cases combining all DeltaOD values produces per cent standard deviation of4.5%. Thus, whether the dose rate effect is clinically significant depends on the specific application of EBT and the desired accuracy.

The optical density (OD) range for the scanners used in film dosimetry is limited due to saturation and noise. As the OD increases, saturation causes the rate of change of the output with respect to the input to become smaller, while at the same time noise remains fairly constant or increases. The combined effect leads to a degradation of the signal-to-noise ratio (SNR) at high optical densities. In this study, the uncertainty in the OD measurement, d(m), is expressed as a function of the optical density d. The functional relationship obtained gives the amplitude w of an interval around d in which d(m) will be found with a given probability p. The relationship w = w(d, p) is later used to determine which OD ranges fulfil a set of requirements on w and p. As an application of the procedure, the noise and saturation characteristics of a commercial film digitizer system are measured. Their contribution to the uncertainties of the dosimetric procedure is reported, and the data are used to provide an optical density range for a given uncertainty and confidence level associated with the digitizer. These data can be further combined with the data from other sources of noise such as film noise in order to estimate the final uncertainty of the dosimetric process.

We demonstrate that a negative-refractive-index material can provide efficient controllable coupling between planar waveguides in a noninvasive fashion. An index matched negative layer acts like optical antimatter to the adjacent cladding layers, leading to significantly reduced effective separation between the guiding layers. This results in nearly mode-independent coupling between the waveguides where the thickness of the negative layer provides the necessary control. When the optical density of the negative coupling layer is different (higher or lower) from the adjacent cladding layers, the negative layer itself can support guided modes. Significant control over coupling can be achieved by engineering the mode structure of the negative waveguide with respect to the modes of the positive waveguides. Furthermore, we demonstrate the possibility of identifying a specific mode and tailoring the waveguide characteristics to achieve any desired level of coupling.

Detailed studies of the basic dosimetric properties of small volumes of PRESAGETM have confirmed its promise as a new material with enhanced properties for 3D dosimetry. PRESAGETM is a transparent polyurethane material containing a radiochromic leucodye. Principle advantages include a relative insensitivity of the dose response to atmospheric exposure, and a radiochromic optical contrast which is light absorbing rather than light-scattering (peak optical density change is at ~633 nm). The absorptive nature of the contrast is more amenable to accurate dose read-out by optical-computed-tomography. This work represents our first feasibility tests of large volumes of PRESAGETM for dosimetric validation of radiation treatments.

Preliminary optical density results on irradiated PRESAGE dosimeter are outlined in this article. PRESAGE is a solid dosimeter, based on a clear polyurethane combined with the leuco-dye leuco-malachite green. The purpose of these measurements was a) to obtain spectra for optimizing the wavelength of a new light source for the equipment and b) to obtain a dose-response relation. 10 PRESAGE cuvettes were given uniform doses from 0.1 to 40 Gy and later read out by spectrophotometer. The instrument used was CAMSPEC M350 Double Beam Spectrophotometer.

This aim of the study was to investigate the cytotoxicity of two commercial and two experimental dental flosses. Two commercial, Oral B® Essential Floss (nylon-waxed) and Thai Silk Floss (silk-waxed), and two experimental, Floss X (nylon-waxed) and Floss Xu (nylon-unwaxed) dental flosses were used. The cytotoxic assay was performed by using cell cultures (L929) which were subjected to cell viability test with methyl-tetrazolium. Each floss specimen (0.4 g) was placed in 1 ml of Minimum Essential Medium at 37°C with 5% CO2 at 100% humidity in an incubator for 24 hours. After incubation, the cell mitochondrial activity was evaluated for detecting viable cells using optical density as per the guidelines of ISO 10993-5:2009(E). Cytotoxic effects were evaluated by measuring percentage of cell viability at 3 points of time- 5 mins, 30 mins, and 1 hr. The results showed that two commercial dental flosses and Floss X had cell viability about 90% at the three time points; however, the experimental Floss Xu presented 80% cell viability at 5 min and

The production of biosurfactant by Pseudomonas putida has been studied. P. putida FNCC 0071 was grown in the nutrient broth medium supplemented with NaCl and crude palm oil (CPO). The effect of CPO concentration and fermentation time on the biosurfactant production were evaluated. The biosurfactant production was evaluated every 24 h for 10 days by optical density, surface tension and emulsification index. The best culture medium was found to be medium containing 5% v/v of CPO with 5 days of incubation time. The biosurfactant was identified as rhamnolipids.

The article provides a comparison of the main valuation techniques for a regulated parameter of printability of the offset paper by current standards GOST 24356 and ISO 3783: 2006. The results of development and implementation of a complex test scale for management and control the quality of printed production are represented. The estimation scale is introduced. It includes normalized parameters of print optical density, print uniformity, picking out speed, the value of dot gain, print contrast with the added criteria of minimizing microtexts, a paper slip, resolution threshold and effusing ability of paper surface. The results of analysis allow directionally form surface properties of the substrate to facilitate achieving the required quality of the printed image parameters, i. e. optical density of a print at a predetermined level not less than 1.3, the print uniformity with minimal deviation of dot gain about the order of 10 per cents.

Production of Gold fish (Cyprinus carpio Linn) in Indonesia has always increased from 2013 to 2015 year by year with increasing average 2% per year. The amount of production was respectively 571.892 tonnes, 1129.273 tonnes, and 1186.674 tonnes. There were almost no problems to sale of gold fish because it had a good enough prospect. The aims of this research were Isolation of spore protein of Myxobolus koi by using SDS-PAGE to analyze immun respons and survival rate gold fish that immunized with spore protein of Myxobolus koi. The method of this research used experimental method, and belonged to 4 treatments that are: Controle = the group of gold fish not immunized with protein spore of Myxobolus koi neither infected by Myxobolus koi (T1). The group immunized and infested by spore of Myxobolus koi (T2), The group which immunized and not infested by Myxobolus koi (T3), and The group only infested by Myxobolus koi (T4). The dose of immunostimulant was 5 ml in 1 kg of food. The result showed that there were two bands of whole spore protein with molecule weight (MW) 150 kDa and 72 kDa and one band of crude protein Myxobolus koi with molecule weight 73 kD and the optical density point was 0.132 on the first day and increased to 0.769 on the 56 th day. The result also showed that the immun respons and survival rate increased from 27% to 86% in chellence test. The protein spore of Myxobolus koi can used to develops material for immunostimulant and to prevent the myxobolusis.

The aim of this study was to develop a new safe and effective hemostatic gauze material by promoting in situ thrombin induction on the surface of gauze, and the optimal preparation conditions were determined by varying the CaCl2 concentration, reaction time, and temperature. Under each condition, the thrombin amount (optical density) and plasma clotting time were measured, and the results showed that the best condition for preparation of this new gauze/plasma composite (GP) is a CaCl2 concentration of 0.08 mol l−1 at 35 °C for 2.5 h. Temporal and water stability tests showed that the gauze is washable and can be stored without loss of quality. Furthermore, the water and blood absorption and whole blood clotting time were compared between the GP and oxidized cellulose (OC), demonstrating that the hemostatic effect of the new material was similar to that of OC; however, the thermophysical stability of GP was superior to that of OC. The good hemostatic effect of the new hemostatic gauze was verified in a rabbit artery bleeding model, which is considered to be due to the presence of thrombin on its surface. These results are expected to provide important guidance in the continued search for new types of hemostatic gauze.

This note investigates the increase of the sensitivity of radiochromic film by layering the film together. Investigations with up to five layers of radiochromic film placed together as a single dosimeter have allowed accurate two-dimensional dosimetry at low radiotherapy doses. The sensitivity of the response of the layered film increases with the number of layers, with the five-layer dosimeter increasing the change in optical density by 4.3 +/- 0.2 times that for a single layer film at 670 nm readout wavelength. Measurements in the penumbral region of a 6 MV x-ray beam show that the spatial resolution is slightly reduced with the layered film. The distance across the region from 20 to 80% of the maximum dose at the beam edge (20/80% penumbra) measured at 1.5 cm depth was measured as 3.1 +/- 0.3 and 3.5 +/- 0.3 mm for one and five layers, respectively. Thus no major reduction in spatial resolution was found by layering the film to five layers but the sensitivity was increased by 430% at 670 nm readout wavelength.

It is found that a laser with an anisotropic cavity containing an absorbing medium may exhibit no response of the output radiation intensity to the modulation of the optical density of the absorbing medium in the presence of a magnetic field. The conditions when this effect may be observed are determined, and its possible applications are briefly discussed.

A new method of measuring dose using GAFchromic MD-55-2 type film is proposed. It involves 2D fitting of optical density, as a function of both wavelength and dose, to a set of measured calibration data. An unknown dose to a film can then be determined by minimizing the chi-square between the measured optical densities and the fitted calibration data. The methodology was tested, using 60Co calibration, by measuring the dose deposited in films irradiated by a 32p source in a semi-infinite geometry. The results are compared with the expected dose obtained From beta counting, taking into account the dose loss correction due to various attenuating materials, including the film substrate itself, which was determined to be 20%. It was found that the root mean relative deviation between the measured and expected doses was approximately 3%. The excellent agreement also demonstrated the possibility of calibration between gamma and beta particles.

Measurements were made of the absorption of laser radiation at the wavelengths of 193, 248, and 353 nm in optical materials at the moment of action of an electron beam. The dependence of the optical density of a material on the power density of the electron beam was linear. The coefficient of proportionality κ in this dependence was a parameter of the material and it was governed by the properties of short-lived colour centres. The value of κ was determined for MgF2, CaF2, BaF2, and Al2O3 crystals, as well as for quartz glasses. In the case of MgF2 the parameter was κ = 29 ± 6, 150 ± 20, and 14 ± 6 cm2 GW-1 at λ = 193, 248, and 353 nm, respectively. For CaF2 and BaF2 its value was κ ≈ 100 cm2 GW-1. Amplification was observed in Al2O3 at λ = 193 and 248 nm: in this case κ was negative: —2.0 and —0.5 cm2 GW-1, respectively.

To create an optical density map of 3D dosimeter phantoms, the ratio of the transmission profile (either a line or planar) acquired after irradiation of the dosimeter and a pre-irradiation reference scan of the same dosimeter phantom is taken. Any uncertainty in repositioning of the phantom may result in an uncertainty in the optical density map and finally also in the derived dose maps. Correct repositioning is paramount when scanning noncylindrical dosimeter phantoms as any repositioning error will give rise to severe imaging artifacts. We hereby propose a different scanning technique that does not require any repositioning of the dosimeter phantom. In this method, no pre-irradiation san is recorded but the dosimeter phantom is scanned twice with light at two different wavelengths. It is demonstrated that this method is accurate in scanning non-cylindrical anthropomorphic shaped phantoms.

Escherichia coli detection was conducted using an optical disk drive tester. A sample of E. coli was mixed in deionized water to obtain an optical density of 0.1 at a wavelength of 600 nm. The solution was dropped onto an oxide-coated disk, on which positioning marks had been made, and dried. Two-dimensional imaging of the E. coli dispersed on the surface was carried out using the marks, and the image obtained was similar to that obtained by an optical microscope. The results indicate that this system can be used to identify the size and number of E. coli.

We investigated a ballistic imaging technique using a femtosecond optical Kerr gate (OKG) made of SrTiO3 crystal (STO). High-contrast images of a 1.41 line pairs per mm (lp mm−1) section of the resolution test chart placed behind a turbid medium were obtained. The STO OKG had greater capacity to acquire high quality images at a high optical density than the quartz OKG, showing that the STO is a promising OKG medium due to its large nonlinear susceptibility.

Computer-aided diagnosis systems for mammography have been developed in order to assist radiologists in the diagnostic process by providing a reliable and objective discrimination of benign and malignant mammographic findings. The effectiveness of such systems is based on the image features extracted from mammograms, which are mainly related to the morphology, texture and optical density of the suspicious abnormality. There are many methodologies reported in the literature able to provide a mathematical description of a mammographic lesion. In this paper, we apply various feature extraction methodologies on cases containing clusters of microcalcifications. Our purpose is to compare their performance in large scale in terms of classification accuracy and to investigate their potentiality in discriminating benign from malignant clusters. Experiments were performed on 1715 cases (882 benign and 833 malignant) extracted from the Digital Database of Screening Mammography, which is the largest publicly available database of mammograms. The results of our study indicated that texture features outperformed the rest of the considered categories, while the combination of the best features optimized the classification results, leading to an area under the receiver operating characteristic curve equal to 0.82.

We present the design, fabrication, and verification of a microfluidic platform for optical monitoring of bacterial biofilms. Biofilm formation characterizes the majority of infections caused by bacteria that are developing increased resistance to traditional antibiotic treatment, necessitating the development of reliable tools not only for study of biofilm growth, but also for in situ examination of the response to applied stimuli. The presented platform was used to continuously and non-invasively observe the dependence of Escherichia coli biofilm formation on bacterial signaling by monitoring the change in biofilm optical density over the growth period. Results were corroborated by measurement of biofilm morphological properties via confocal microscopy, and statistical analysis was applied to verify the repeatability of observed optical and morphological differences in the biofilms formed. The presented platform will be used to characterize biofilm formation and response in drug discovery applications.

Cold and optically dense gases of atomic rubidium are produced using buffer gas cooling in combination with rapid, high-flow vapor injection. The observed rubidium density is 3?1012?cm?3 at a gas temperature of ~20?K, leading to an optical density of the order of 200.

A tri-branched tri-anchoring organic dye (Dye 2) consisting of one donor (D) in the center, three π bridges, and three acceptor (A) groups in the order of D–π–A was designed and each A group ended with a COOH anchoring group. The Dye 2-sensitized TiO2 exhibited a significantly improved photoelectrochemical response under visible light illumination, compared to TiO2 sensitized with a mono-anchoring dye (Dye 1). It is due to the enhanced optical density and more efficient interfacial electron transfer from the photoexcited dye to the TiO2.

The introduction of optical computed tomography (optical-CT) offers economic and easy to use 3-D optical readout for gel dosimeters. However, previous authors have noted some challenges regarding the accuracy of such imaging techniques at high values of optical density. In this paper, we take a closer look at the 'cupping' artefact evident in both light-scattering polymer systems and highly light absorbing phantoms using our CCD-based optical scanner. In addition, a technique is implemented whereby the maximum measurable optical absorbance is extended to correct for any errors that may have occurred in the estimated value of the dark current or ambient light reaching the detector. The results indicate that for absorbance values up to 2.0, the optical scanner results have good accuracy, whereas this is not the case at high absorbance values for reasons yet to be explained.

This brief work-in-progress outlines two methods that we have attempted for determining the dose at which the linear relation between optical density of a PRESAGE™ dosimeter and the dose deposited breaks down. Both methods were equally successful in mapping the linear relation up to an optical density of approximately 6.25 cm−1 (absorbance 2..5), but no saturation was found in this region.

We designed novel hybrid type bottom antireflective coating (BARC) materials for ArF lithography. The optimum extinction coefficient (k) value of the new organic BARC materials (HEART004) is 0.71 at a 32 nm film thickness. Its plasma etch rate is higher than that of ArF photoresist under Cl2/O2 plasma etch conditions. The critical dimension (CD) uniformity of 0.13 µm L/S patterns could be controlled below 10 nm and the etch bias, which represents the CD difference before and after BARC etching, could be less than 10 nm. Our new organic BARC materials show a good compatibility with both (meth)acrylate-type photoresist (PAR101, PAR710) and cycloolefin/maleic-anhydride-type photoresist (DHA1001) without any undercut or footing.

Super-resolution readout for read-only optical disks was demonstrated using a photochromic mask layer. Nonlinear transmittance change, which is desirable for effective super-resolution readout, was achieved using a the photochromic mask layer with an optical density of 0.5. The photochromic super-resolution method is expected to increase the recording density of not only read-only disks, but also magneto-optical and phase change disks.

It is shown here, by means of the reciprocal statistical density and the Ewald method, that the decrease of the photographic emulsion refractive index compensates most of the effect of the thickness shrinkage in the case of a transmission three-dimensional absorbing hologram. Moreover, the « symmetric » recording of the hologram is shown to be the most interesting configuration in the case of real-time holographic interferometry where the shrinkage and the refractive index variation of the emulsion do not generate spurious fringes, if they are uniform.

A relationship between the structure of the sclera and its light scattering properties is proposed. The relative optical density as a function of wavelength in the infrared was measured for three sclera and a good correlation with the predicted function was found. The angular distribution of the scattered light at 632.8 nm as well as the degree of polarisation of the scattered light at zero angle was measured for three sclera; from these results the total transmission of the sclera was determined.

A promising material for use in a UV film badge dosemeter is diazo film. The optical density of this substance changes on exposure to ultraviolet radiation. The present paper reports some of the relevant factors in the processing of the film and also on its spectral sensitivity. It is evident from our results that development time and volume and concentration of ammonia solution should be standardised. However, after the film has been developed, it is not affected by subsequent UV exposure or by storage for up to one month. Although maximum sensitivity occurs at 405 nm, there is still an easily measurable response at 254 nm. It is concluded that provided procedures are standardised, Diazochrome KBL film is an inexpensive, convenient material for a UV film badge dosemeter with measurable sensitivity down to 254 nm.

A discussion is given of the optical properties utilized to form thermographic prints, the method of treating the mottled appearance of prints, the experimental means for determining the characteristic parameters entering into the theoretical formulation, and the experimental results concerning heat transfer and optical density of the thermal prints. The experimental results confirm that the theory developed here encompasses and describes correctly all significant practical cases. The theory fails only for very coarse prints, which, however, represent a case of little practical interest.

The optical density Fricke dosemeter FeSO4 solutions irradiated by protons of mean energy 19.3 MeV was measured as a function of dose, determined with an ionisation chamber. A G-value of 14.5+or-0.6 (100 eV)-1 was found.

Low-energy (h(cross) omega =21.2 eV) photoemission measurements of liquid gallium made over the temperature range 320K to 820K are reported. The optical density of states derived from the spectra contrasts with a free-electron curve and reflects the main features observed in high-energy X-ray-induced spectra for solid gallium films. Little variation is found in the spectra with change of temperature.

An instrument is described for recording the optical density of smoke in a chimney. It was designed for the study of smoke emission from domestic-heating equipment at the Fuel Research Station, and its readings are independent of changes in the characteristics of the components and of variations in the electricity power supply. This is achieved by using a double-beam, nuil-balancing system with a single light source and a single barrier-layer photoelectric cell.

A versatile double-beam microdensitometer has been constructed in which the source of light is the spot of a high resolution cathode-ray tube. The spot position is under computer control and the optical density, digitized by a novel analogue-to-digital converter circuit, is read directly into the computer. The instrument is capable of making an integrated intensity measurement in about 02 s with an accuracy to about 3%.

A recording optical smoke meter is described which has a high sensitivity. The optical density of smoke in a flue is compared by photoelectric means with that of an optical wedge, which is then rotated by an electrically operated servo-system until the two densities are the same. The angular position of the wedge is detected by a transducer, which provides a millivolt output proportional to the rotation of the wedge. A multi-channel switching unit, electrically coupled to a recorder, is incorporated; this enables any number of different flue units, up to the capacity of the recorder, to be used or other variables to be recorded at the same time. The range of the instrument can be varied by changing the value of the optical wedge in the balancing unit or by varying the transducer output to obtain full-scale deflection of the recorder for any desired rotation of the wedge. The calibration in terms of millivoltage output against optical density is linear, provided that the optical wedge and output transducer have linear characteristics. The output is stable to ±0.6% of full-scale reading for ambient temperature changes in the range of 55-80° F, and the sensitivity is such that densities of the order of 0.005 can be recorded.

The large-area responses of ten emulsions (five `conventional', three nuclear research and two Schumann-type) have been examined for electron energies between 7 and 60 kev. The responses are considered in terms of the initial slope of the optical density D-exposure E curve, the value of E for D = 1, the saturation density Ds and the number of grains rendered developable per incident electron. For high D/Ds values, the forms of the experimental (D, E) relationships are found to depart from those expected if the mechanism of rendering developable a photographic grain were a simple single hit process, in a way that depends on the electron energy. The effect on the single hit relationship of the dependence of the exposure on the depth of electron penetration is considered, allowing a more complete inter-pretation of the shape of the (D, E) curves in terms of simple descriptions of electron-grain interactions. The high sensitivities of the nuclear and Schumann emulsions make feasible the direct recording at useful magnifications of electron images formed by low energy electrons.