Modeling the optical properties of mineral particles suspended in seawater and their influence on ocean reflectance and chlorophyll estimation from remote sensing algorithms

The optical properties of mineral particles suspended in seawater were calculated from the Mie scattering theory for different size distributions and complex refractive indices of the particles. The ratio of the spectral backscattering coefficient to the sum of the spectral absorption and backscattering coefficients of seawater, b(b)(lambda)/[a(lambda) + b(b)(lambda)], was analyzed as a proxy for ocean reflectance for varying properties and concentrations of mineral particles. Given the plausible range of variability in the particle size distribution and the refractive index, the general parameterizations of the absorption and scattering properties of mineral particles and their effects on ocean reflectance in terms of particle mass concentration alone are inadequate. The variations in the particle size distribution and the refractive index must be taken into account. The errors in chlorophyll estimation obtained from the remote sensing algorithms that are due to the presence of mineral particles can be very large. For example, when the mineral concentration is 1 g m(-3) and the chlorophyll a concentration is low (0.05 mg m(-3)), current global algorithms based on a blue-to-green reflectance ratio can produce a chlorophyll overestimation ranging from approximately 50% to as much as 20-fold.     

Interference colours of soap bubbles

In this article, we present a new versatile method for calculating the interference colour of any configuration of thin, optically isotropic, dielectric films. This method is free from common weakness of previous methods, namely the poor accuracy for large angles of incidence of light. This method gives full control over the accuracy and speed of computations, and allows for adjustments of the parameters according to the physical and chemical properties of the film, in order to present the optimal results. We also present a formula to model the thickness of thin films made up of liquids, such as soap bubbles.     

The thermomechanical processing of titanium and Ti-6Al-4V thin gage sheet and plate

A new method for producing low-cost titanium powder, the Armstrong Process, has proven to be a scalable process. The process, which reduces TiCl₄ vapor in a molten stream of sodium to produce pure titanium and NaCl, can also be used to in-situ manufacture Ti-6Al-4V alloy powder. Armstrong Process titanium and Ti-6Al-4V powders were used to produce plate by vacuum hot pressing. Also, thin gage sheet was produced by cold rolling solid-phase sintered titanium and Ti-6Al-4V powder compacts. Chemical analysis and mechanical testing revealed that processed Armstrong titanium and Ti-6Al-4V sheet and plate had compositions and properties similar to those of grade 2 titanium and grade 5 Ti-6Al-4V. For more information, contact John D.K. Rivard, Strategic Analysis, 3811 N. Fairfax Drive Suite 700, Arlington VA 22202; e-mail jrivard@sainc.com.     

The modeling and analysis of a butting assembly in the presence of workpiece surface roughness and part dimensional error

Butt joints are frequently used in assembly processes. However, relatively little attention has been paid to the proper design and selection of butt joint geometries and processes. In this paper, the assembly accuracy performance of different butt joint geometries and joining processes has been studied by using analytical models for part misalignment in the presence of part dimensional errors, surface roughness, and surface waviness. Our analysis shows that both short-term roughness, as well as long-term waviness, has an effect on the assembly precision levels. The analysis is verified statistically using a simulation program; experiments are conducted using this program to show that the differences in the performance between different butt joining methods can be significant. Therefore, proper design and selection of forming butting assemblies can have important impacts on the assembly precision.     

Propolis as an antidegradant and biocidal agent for natural rubber

The numerous applications of polymers in many areas of our lives make it necessary to protect them from aging. Increases in the safety and time of polymer material exploitation demands the application of antidegradants with broad scopes of action. In this study, crude propolis, originating from two geographical regions of Poland, was used to protect peroxide‐cured natural‐rubber vulcanizates filled with silica or carbon black from degradation by oxygen, ozone, and microorganisms. Thermogravimetry analysis confirmed the stability of propolis under the curing conditions. From vulcametric torque measurements and determinations of the mechanical properties, we determined that the incorporation of propolis did not adversely affect the performance of the natural‐rubber vulcanizates. The addition of propolis to the rubber mix made the vulcanizates resistant to thermooxidative and ozone aging and protected them from biodegradation in soil and the action of microorganisms. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45911.     

On-line measurements in pig carcass classification: Repeatability and variation caused by the operator and the copy of instrument

For nearly all pigs slaughtered in the EU, the lean meat content is assessed on-line at the slaughter line. The assessment is made indirectly by an instrument performing a number of informative measurements including the thickness of back fat as one of the most important and common measurements. Several types of instruments are used for making the measurements. The quality of the calibration (the prediction ability) has to be approved by the EU Commission. However, the maintenance of instruments, training of operators, working conditions and other factors influencing the routine are quite as important for the accuracy as the calibration. As a part of an EU funded project, partners representing thirteen European countries have investigated the instruments used in their countries focusing on the precision of indirect measurements. The preconditions have differed considerably between the countries resulting in a wide range of estimates of the repeatability and the reproducibility (precision) of fat and muscle thickness. Totally, there have been three different types of manual instruments - invasive probe instruments from three manufacturers, non-invasive ultrasound and callipers. Furthermore, the precision of two automatic instruments with respect to lean meat content has partly been estimated. Even though neither the aim nor the design of the experiments was set for a direct comparison between different instruments, none of them seemed to deviate notably from the others with respect to the precision of fat thickness. In this study, the only investigated influencing factors were the variations in operators and copies of instruments. Generally, the variations between operators were more important than the variation between copies of the same type of instrument.     

Molecular packing and symmetry of two-dimensional crystals

Periodic arrangements on surfaces resulting from monolayer formation are critical in determining the electronic structure of thin films, the adhesion of surface coatings, the properties of lubricants, and the polymorphic form of heteronucleated crystals. Unlike substrate-directed chemisorption, the process of physisorption is highly responsive to molecular structure and stands out as a controllable method of creating variable surface patterns with periodicities on the low end of the nanoscale. Despite decades of study focused upon such ordered structures, the principles guiding the formation of these two-dimensional crystals have been obscured by the lack of a systematic and critical compilation. Thus, prediction of two-dimensional structure based upon the composition of the individual building blocks remains in its infancy. Here we demonstrate through the compilation and analysis of a database of two-dimensional structures that molecular-scale patterns are dictated by the same factors that determine bulk crystal structure, but these factors give rise to different preferred packing symmetries. In marked contrast to three-dimensional systems, achiral molecules in two-dimensional crystals are likely to adopt chiral structures, and racemic mixtures are expected to produce enantiopure domains. The determination of plane group frequencies allowed experimental verification of Kitaigorodskii's 50-year old theory of close packing as applied to two-dimensional tiling. This fundamental comparison between bulk crystals and physisorbed monolayers provides new tools and directions for future exploration in the engineering of surfaces with prescribed two-dimensional patterns.     

The Effects of Cadmium at Low Environmental Concentrations on THP-1 Macrophage Apoptosis

Cadmium at environmental concentrations is a risk factor for many diseases, including cardiovascular and neurodegenerative diseases, in which macrophages play an important role. The aim of this study was to evaluate the effects of cadmium at low environmental (nanomolar) concentrations on apoptotic processes in THP-1(acute monocytic leukemia cells line)-derived macrophages, with special focus on mitochondrial events involved. Macrophages were incubated with various cadmium chloride (CdCl₂) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM and 2 µM CdCl₂. Cell viability was measured using flow cytometry. Flow cytometric measurement (annexin V/FITC (annexin V/fluorescein isothiocyanate) and PI (propidium iodide) double staining) was used to quantify the extent of apoptosis. Fluorescence and confocal microscopy were used for imaging of apoptosis process. Changes in mitochondrial membrane potential were monitored using cytofluorimetry after cell staining with JC-1(5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazol-carbocyane iodide) probe. Mitochondrial ROS (reactive oxygen species) levels were measured cytofluorimetrically after incubation of cells with mitochondrial superoxide indicator (MitoSOX) red fluorescent marker. The mRNA expression of Bcl-2 and Bax was analysed with qRT-PCR. Our study demonstrates that cadmium, even at low environmental concentrations, exerts mitochondrial toxicity in THP-1 macrophages. Forty-eight-hour exposure to very low concentrations reduces cell viability and results in cell death by apoptosis and necrosis. The decrease in mitochondrial membrane potential, increased ROS production, increased Bax and decreased Bcl-2 mRNA expression are mitochondrial events involved in cadmium-induced apoptosis.     

Slaughter value and flesh characteristics of European catfish (Silurus glanis) fed natural and formulated feed under different rearing conditions

The experimental material was comprised of European catfish (Silurus glanis) individuals aged 2.5 years that were reared on natural feed in earthen ponds and individuals aged 1.5 years cultivated intensively on formulated feed in recirculating systems. Weight gain and morphometric parameters were measured along with physical and color characteristics and proximate composition of fillets. Despite the different age and diets of the fish, no differences were observed in the linear biometric indices. The total weight of the fish of both groups and their condition coefficients were also similar. In addition, no differences were reported in their body weight or head and gutted (H&G) carcass and fillet yields. Proximate composition analysis demonstrated a lack of differences in the contents of dry matter. Of the dry matter, differences were reported in the fat content, which was higher in the catfish fed formulated feed. The color of the fillets was characterized by high values of lightness, negative values of redness, and positive values of yellowness, and the fish fed formulated feed displayed higher saturation of green. The flesh of both groups of catfish demonstrated similar pH values and water retention capacity, whereas the values of thermal drip appeared to be higher in the fish fed formulated feed.