Modeling Growth Rate and Assessing Aflatoxins Production by Aspergillus flavus as a Function of Water Activity and Temperature on Polished and Brown Rice

Abstract: The aim of this study was to model the radial growth rate and to assess aflatoxin production by Aspergillus flavus as a function of water activity (a_w 0.82 to 0.92) and temperature (12 to 42 °C) on polished and brown rice. The growth of the fungi, expressed as colony diameter (mm) was measured daily, and the aflatoxins were analyzed using HPLC with a fluorescence detector. The growth rates were estimated using the primary model of Baranyi, which describes the change in colony radius as a function of time. Total of 2 secondary models were used to describe the combined effects of a_w and temperature on the growth rates. The models were validated using independent experimental data. Linear Arrhenius–Davey model proved to be the best predictor of A. flavus growth rates on polished and brown rice followed by polynomial model. The estimated optimal growth temperature was around 30 °C. A. flavus growth and aflatoxins were not detected at 0.82 a_w on polished rice while growth and aflatoxins were detected at this a_w between 25 and 35 °C on brown rice. The highest amounts of toxins were formed at the highest a_w values (0.90 to 0.92) at a temperature of 20 °C after 21 d of incubation on both types of rice. Nevertheless, the consistencies of toxin production within a wider range of a_w values occurred between 25 to 30 °C. Brown rice seems to support A. flavus growth and aflatoxin production more than the polished rice. Practical Application: The developed models can be used to estimate to what extent the change in grain ecosystem conditions affect the storage stability and safety of grains without the need for running long‐standing storage study. By monitoring the intergranular relative humidity and temperature at different locations in the storage facility and inputting these data into the models, it is directly possible to assess either the conditions are conductive for the growth of A. flavus or aflatoxin production.     

Hydrogen Storage in Metal-Organic Frameworks

Recent decades have witnessed the explosive emergence of metal organic frameworks (MOFs) as functional ultrahigh surface area materials. Categorized as an intriguing class of hybrid materials, MOFs exhibit infinite crystalline lattices with inorganic vertices and molecular-scale organic linkers. Fortunately, the large internal surface areas and overall pore volumes, adjustable pore sizes, ultralow densities, and tunable framework–adsorbate interaction by ligand functionalization and metal choice, enable MOFs to be promising materials for wide applications. In particular, these remarkable properties render MOFs potential hydrogen storage materials. By virtue of their exceptionally high surface areas, unparalleled tenability and structural diversity, MOFs have become a hotspot of research within the scientific community. This paper reviews the different methods used for the synthesis of MOFs, the relationship between structural features and hydrogen adsorption, the strategies for hydrogen uptake improvement as well as the molecular simulation.     

Interpolation-Free Fractional-Pixel Motion Estimation Algorithms with Efficient Hardware Implementation

This paper presents interpolation-free fractional-pixel motion estimation (FME) algorithms and efficient hardware prototype of one of the proposed FME algorithms. The proposed algorithms use a mathematical model to approximate the matching error at fractional-pixel locations instead of using the block matching algorithm to evaluate the actual matching error. Hence, no interpolation is required at fractional-pixel locations. The matching error values at integer-pixel locations are used to evaluate the mathematical model coefficients. The performance of the proposed algorithms has been compared with several FME algorithms including the full quarter-pixel search (FQPS) algorithm, which is used as part of the H.264 reference software. The computational cost and the performance analysis show that the proposed algorithms have about 90% less computational complexity than the FQPS algorithm with comparable reconstruction video quality (i.e., approximately 0.2 dB lower reconstruction PSNR values). In addition, a hardware prototype of one of the proposed algorithms is presented. The proposed architecture has been prototyped using the TSMC 0.18 μm CMOS technology. It has maximum clock frequency of 312.5 MHz, at which, the proposed architecture can process more than 70 HDTV 1080p fps. The architecture has only 13,650 gates. The proposed architecture shows superior performance when compared with several FME architectures.     

Next generation of low global warming potential refrigerants: Thermodynamic properties molecular modeling

The recent global agreement signed in Kigali to limit the use of hydrofluorocarbons (HFCs) as refrigerants, starting by 2019, has promoted an active area of research toward the development of low global warming potential (GWP) new refrigerants. Hydrofluoroolefins (HFOs) have been proposed as a low GWP alternative to third generation HFC refrigerants, but further work on fully characterizing them and their blends with other compounds is still required to fully assess their performance to replace the ones in current use. In this work, the polar and perturbed chain statistical associating fluid theory coupled with the density gradient theory is used to predict the vapor–liquid equilibrium, isobaric heat capacity, speed of sound, and surface tension of selected HFC and HFO‐based commercial azeotropic blends as fourth generation low GWP refrigerants, seeking for a predictive tool for these properties. © 2017 American Institute of Chemical Engineers AIChE J, 63: 250–262, 2018     

Wearable Self-Powered Electrochemical Devices for Continuous Health Management

The wearable revolution is already present in society through numerous gadgets. However, the contest remains in fully deployable wearable (bio)chemical sensing. Its use is constrained by the energy consumption which is provided by miniaturized batteries, limiting the autonomy of the device. Hence, the combination of materials and engineering efforts to develop sustainable energy management is paramount in the next generation of wearable self-powered electrochemical devices (WeSPEDs). In this direction, this review highlights for the first time the incorporation of innovative energy harvesting technologies with top-notch wearable self-powered sensors and low-powered electrochemical sensors toward battery-free and self-sustainable devices for health and wellbeing management. First, current elements such as wearable designs, electrochemical sensors, energy harvesters and storage, and user interfaces that conform WeSPEDs are depicted. Importantly, the bottlenecks in the development of WeSPEDs from an analytical perspective, product side, and power needs are carefully addressed. Subsequently, energy harvesting opportunities to power wearable electrochemical sensors are discussed. Finally, key findings that will enable the next generation of wearable devices are proposed. Overall, this review aims to bring new strategies for an energy-balanced deployment of WeSPEDs for successful monitoring of (bio)chemical parameters of the body toward personalized, predictive, and importantly, preventive healthcare.     

The common,different and unique effects of metallic engineered nanomaterials: an analytic perspective

From regulatory perspectives, there has been a debate in the scientific literature as to whether or not metallic engineered nanomaterials (ENMs) should be treated as new chemicals in terms of their toxic effects upon biological species. This debate has prompted us to examine the scientific evidence to validate those paradoxical claims. Investigations covering the effects of metallic ENMs and metal-based ions in the same study were included in this research. The findings reported herein suggest that the different arguments are valid if a wider perspective takes into account the common, different and unique effects of metallic nanoparticles versus metal-based ions. This perspective has been evident from investigations of aquatic (lower organisms such as Daphnia magna and higher organisms like zebra fish) and other organisms (e.g., microbes, nematodes, animal and human cells). It is suggested that the regulation of metallic nanomaterial-based products be transformed to a tier-based approach as a function of the common, different and unique effects to manage the complexity brought into light due to the infinite combinations of the particle physical–chemical properties.     

On inverse kinematics with inequality constraints: new insights into minimum jerk trajectory generation

The problem of inverse kinematics is revisited in the present paper. The paper is focusing on the problem of solving the inverse kinematics problem while minimizing the jerk of the joint trajectories. Even though the conventional inverse kinematics algorithms have been proven to be efficient in many applications, it has been proven that constraints on the accelerations or the jerk cannot be guaranteed, and even yields to divergence or makes the problem unsolvable. The proposed algorithm yields smooth velocity and acceleration trajectories, which are highly desired features for industrial robots. The algorithm uses the joint jerk as the control parameter instead of the classical use of the joint velocity as result constraints on the jerk function can be easily incorporated. To validate the proposed approach, we have conducted several simulations scenarios. The simulation results have revealed that the proposed method can efficiently solve the inverse kinematics problem while considering constraints on the joint acceleration and jerk.     

In vitro assessment of bone-implant interface using an acoustic emission transmission test

The aim of this in vitro study was to determine the feasibility of monitoring the primary stability of dental implants using a simple transmission test with acoustic emission. Forty screw-shaped titanium dental implants were installed in the middle of 10 fresh bovine ribs obtained from different animals. The implants were divided into two size groups, 8.5 mm x 3.5 mm and 13 mm x 4.5 mm, and were inserted in either tight- or loose-fitting conditions. For each implant, pulses of acoustic energy were injected at the centre of a customised gold abutment 3 mm in height using a standard pencil lead break source (Hsu-Nielsen source). A total of 30 acoustic emission recordings were made for each implant in which the transmitted energy was measured on the surface of the bone using an acoustic sensor mounted at the middle of the rib. The transmitted acoustic energy for the implants under tight-fitting conditions was significantly higher than for the loose-fitting for both sizes of implant. The acoustic emission energy values for the 13 mm implants were also higher than for the 8.5 mm implants. The results indicate that implants with good primary stability (tight-fitting) had higher acoustic emission energy than implants where primary stability was poor (loose-fitting). The longer and wider implants produced higher acoustic emission energy than shorter and narrower implants. Together, the findings suggest that a simple transmission test, properly calibrated, should be able to assess the quality of the contact between the implant and the bone in the clinical situation.     

The use of lead dodecanoate as an environmentally friendly coating to inhibit the corrosion of lead objects: Comparison of three different deposition methods

An aqueous sodium dodecanoate solution has been used for the formation of a protective coating for lead. Three deposition methods have been compared: immobilization using cyclic voltammetry, immersion and amperometry. Apart from this, we tested a reduction pretreatment of the lead surface (−1.5 V during 600 s) in order to obtain a more reproducible coating, resulting in a better corrosion protection behavior. The corrosion inhibition properties were examined using potentiodynamic polarization curves and electrochemical impedance measurements in a standard corrosive environment.