Adsorptive features of chitosan entrapped in polyacrylamide hydrogel for Pb2+, UO2(2+), and Th4+

Chitosan (Ch) was entrapped in polyacrylamide (PAA) by direct polymerization of acrylamide in a suspension of Ch. The adsorptive features of PAA-Ch and Ch were then investigated for Pb2+, UO2(2+), and Th4+ in view of dependency on ion concentration, temperature, and kinetics. Additional considerations were also given to their ion selectivity and reusability. Isotherms were L and H type of Giles classification and evaluated with reference to Langmuir, Freundlich, and Dubinin-Radushkevich (DR) models. PAA-Ch had higher adsorption capacity than Ch for all studied ions so that the sequences were Th4+>Pb2+>UO2(2+) concordantly with their affective ionic charges. The affinity of Ch in PAA increased for Pb2+ and UO2(2+) but did not change for Th4+. The values of enthalpy and entropy changed were positive for all studied ions for both Ch and PAA-Ch. The negative free enthalpy change value indicated that the adsorption process is spontaneous in the sequence of Th4+>or=Pb2+>UO2(2+). Free energy values derived from DR model implied that the sorption process is the ion exchange. Well compatibility of adsorption kinetics to the pseudosecond-order model predicate that the rate-controlling step is a chemical sorption. The study for ion selectivity showed that both Ch and PAA-Ch had the highest affinity to Pb2+. The reusability tests for Ch and PAA-Ch for Pb2+ for five uses showed that complete recovery of the ion was possible. The studied features of PAA-Ch suggest that the material should be considered as a new adsorbent. It is envisaged that the use of Ch in PAA will enhance practicality and effectiveness of Ch in separation and removal procedures.     

An investigation into ballistic performance and energy absorption capabilities of woven aramid fabrics

This paper presents an investigation regarding the ballistic performance of protection panels of different fabric ply numbers used in body armours. Twaron CT 710 type fabric layers of differing numbers are joined by using three stitch types to form the panels and then the panels are subjected to ballistic tests according to NIJ standards. Ballistic performance of the panels is determined by measuring trauma depth and trauma diameter. The energy absorbed by the fabric layers and the energy transmitted to the back of the fabric layers are determined from the trauma depth and trauma diameter values using a different approach. It is shown that the fabric ply number and stitching type have significant effects on ballistic properties and the effect of conditioning is limited.     

Adsorption of boron from boron-containing wastewaters by ion exchange in a continuous reactor

In this study, boron removal from boron-containing wastewaters prepared synthetically was investigated. The experiments in which Amberlite IRA 743, boron specific resin was used were carried out in a column reactor. The bed volume of resin, boron concentration, flow rate and temperature were selected as experimental parameters. The experimental results showed that percent of boron removal increased with increasing amount of resin and with decreasing boron concentration in the solution. Boron removal decreased with increasing of flow rate and the effect of temperature on the percent of total boron removal increased the boron removal rate. As a result, it was seen that about 99% of boron in the wastewater could be removed at optimum conditions.     

Adsorptive properties of As(III) from aqueous solution using magnetic nickel ferrite (NiFe2O4) nanoparticles: Isotherm and kinetic studies

As(III) adsorption on NiFe₂O₄ nanoparticles were systematically investigated by controlling parameters such as stirring rate, pH, initial arsenic concentration, contact duration, temperature, and adsorbent dose. It was observed that the amount of adsorbed arsenic concentration is strongly depended on pH and temperature. The temperature and pH give rise to significant changes in the amount of adsorbed arsenic. As compared with Langmuir and Freundlich isotherms models, the latter is found to be well suited. Pseudo-first order, pseudo-second order, and intraparticle diffusion models were applied to adsorption equilibrium data obtained from the analysis of arsenic with diverse amount of initial concentration.     

An empirical model for kinetics of boron removal from boron-containing wastewaters by ion exchange in a batch reactor

In this study, it was investigated boron removal from boron containing wastewaters prepared synthetically. The experiments in which Amberlite IRA 743, boron specific resin was used was carried out in a batch reactor. The ratio of resin/boron solution, boron concentration, stirring speed and temperature were selected as experimental parameters. The obtained experimental results showed that percent of boron removal increased with increasing ratio of resin/boron solution and with decreasing boron concentration in the solution. Stirring speed and temperature had not significant effects on the percent of total boron removal, but they increased the starting boron removal rate. As a result, it was seen that about 99 % of boron in the wastewater could be removed at optimum conditions. On the other hand, the process kinetics were predicted by using heterogeneous fluid-solid reaction models. It was seen statistically that the kinetics of this process agreed the pseudo- second order model, as follows: X_Bl(1−X_B) = 11,241.5[OH][C]^−1.76[S/L]^2.17exp(−19,57l.2/RT)t^1.24     

Utilization of borogypsum as set retarder in Portland cement production

Boron ores are used in the production of various boron compounds such as boric acid, borax and boron oxide. Boric acid is produced by reacting colemanite(2CaO·3B₂O₃·5H₂O) with sulphuric acid and a large quantity of borogypsum is formed during this production. This waste causes various environmental problems when discharged directly to the environment. Portland cement is the most important material in the building industry. This material is produced by adding about 3-5% gypsum (CaSO₄·2H₂O) to clinker as a set retarder. The aim of this study was to stabilize borogypsum, and to produce cements by adding borogypsum instead of natural gypsum to clinker. Concrete using cement produced with borogypsum was tested to find the mechanical properties and the test values were compared with those of concrete from cement with natural gypsum. Compressive strength of concrete from cement produced with borogypsum was found to be higher than that of natural gypsum. Also, the setting time of cement with borogypsum was longer than that of the Portland cement.     

Effect of Defect Size on Subsurface Defect Detectability and Defect Depth Estimation for Concrete Structures by Infrared Thermography

This study aims to reveal the effect and correlation of delamination size and defect shape for using infrared thermography (IRT) through FE modeling to enhance the reliability and applicability of IRT for effective structural inspections. Regarding the effect of delamination size, it is observed that the temperature difference between sound and delaminated area (\(\Delta \)T) increases as the size of delamination increases; however, \(\Delta \)T converges to a certain value when the area is 40 \(\times \) 40 cm and the thickness is 1 cm. As for the shape of delamination, it can be assumed that if the aspect ratio which is the ratio of the length of the shorter side to the longer side of the delamination is more than 25%, \(\Delta \)T of any delaminations converges to \(\Delta \)T of the same area of a square/circular-shaped delamination. Furthermore, if the aspect ratio is 25% or smaller, \(\Delta \)T becomes smaller than the \(\Delta \)T of the same area of a square/circular-shaped delamination, and it is getting smaller as the ratio becomes smaller. Furthermore, this study attempts to estimate depths of delaminations by using IRT data. Based on the correlation between the size of delamination and the depth from the concrete surface in regard to \(\Delta \)T, it was assumed that it was possible to estimate the depth of delamination by comparing \(\Delta \)T from IRT data to \(\Delta \)T at several depths obtained from FE model simulations. Through the investigation using IRT data from real bridge deck scanning, this study concluded that this estimation method worked properly to provide delamination depth information by incorporating IRT with FE modeling.     

Determination of the Failure Susceptibility of a Flat Die Used in Biomass Pelletizing Machines by Means of FEA-Based Design Exploration

This paper focuses on a design analysis of a flat die used in an agricultural biomass pelletizing machine by considering its high-pressure loading failure susceptibility. The pellet die is one of the key elements in a pelletizing machine, and the strength of the die plate has an important role on the pellet’s quality and producibility. In fact, higher compression ratio (CR—the ratio of effective length and the internal (press channel) diameter of a die orifice/hole) will provide denser pellets which is a desired phenomenon, however, if the compression pressure is too high or CR is not determined to compensate high pressures, the raw material may block the die and the die may experience deformation failure due to overloading. If the desire is to make high-quality pellets with no die failure, optimum flat die hole/orifice design parameters should be used which can provide the best CR for a specific compression pressure. This is the core motivation of this research. In this study, finite element analysis (FEA)-based design exploration has been utilized for a sample single hole flat die with various die geometry parameters against various compression pressure values. Following the FEA design exploration undertaken, a response surface analysis (RSA) was carried out and then estimation models (empirical equations), which could be used to calculate parameters of the die hole/orifice against applied compression pressure and failure susceptibility based on structural stress and deformation, was described. The results gained from the RSA have indicated that the estimation models have high R² values (higher than 98%) which could be used for adequately predicting failure susceptibility indicators. In addition to this, FEM-based simulation printouts have provided useful stress distribution visuals on the die against different compression pressure values. Most especially, the study has highlighted that a detailed structural optimization study may be scheduled in order to obtain die geometry design parameters with a focus on the failure susceptibility.     

Genetic Logic Gates Enable Patterning of Amyloid Nanofibers

Distinct spatial patterning of naturally produced materials is observed in many cellular structures and even among communities of microorganisms. Reoccurrence of spatially organized materials in all branches of life is clear proof that organization is beneficial for survival. Indeed, organisms can trick the evolutionary process by using organized materials in ways that can help the organism to avoid unexpected conditions. To expand the toolbox for synthesizing patterned living materials, Boolean type “AND” and “OR” control of curli fibers expression is demonstrated using recombinases. Logic gates are designed to activate the production of curli fibers. The gates can be used to record the presence of input molecules and give output as CsgA expression. Two different curli fibers (CsgA and CsgA‐His‐tag) production are then selectively activated to explore distribution of monomers upon coexpression. To keep track of the composition of fibers, CsgA‐His‐tag proteins are labeled with nickel–nitrilotriacetic acid (Ni–NTA‐) conjugated gold nanoparticles. It is observed that an organized living material can be obtained upon inducing the coexpression of different CsgA fibers. It is foreseen that living materials with user‐defined curli composition hold great potential for the development of living materials for many biomedical applications.     

Fuzzy diffusion filter with extended neighborhood

Anisotropic diffusion filters, which are motivated from heat diffusion between mediums, have become a widely used technique in the field of image processing. In the initial proposals of anisotropic diffusion filters, 4-neighborhood values with diffusivity functions are computed independently for each spatial location because of numerical approximation. However, anisotropic diffusion filters could not be used in real-time image and video processing applications because they need diffusivity parameters, which must be specified by users in every sampling period. In this study, a fuzzy adaptive diffusion filter using extended neighborhood without diffusivity functions has been developed. The fuzzy adaptive diffusion filter does not require any parameter chosen by user and therefore they could be employed in real-time applications. In the fuzzy adaptive diffusion filter, a similarity transformation by means of relation matrix and fuzzy logic is carried out. Accordingly, the similarity image, output of transformation, is directly used as a heat diffusion coefficient in the diffusion filter. Results show that the fuzzy adaptive diffusion filter is very efficient for removing noise in image while preserving edges.