Improvement of heating uniformity in packaged acidified vegetables pasteurized with a 915 MHz continuous microwave system

Continuous microwave processing to produce shelf-stable acidified vegetables with moderate to high salt contents poses challenges in pasteurization due to reduced microwave penetration depths and non-uniform heating. Cups of sweetpotato, red bell pepper, and broccoli acidified to pH 3.8 with citric acid solution containing 0-1% NaCl were placed on a conveyor belt and passed through a microwave tunnel operating at 915 MHz and 4 kW with a 4 min residence time. The time-temperature profiles of vegetable pieces at 5 locations in the package were measured using fiber optic temperature sensors. Addition of 1% NaCl to the cover solution lowered microwave penetration into vegetable pieces and decreased the mean temperature in cups of acidified vegetables from 84 to 73 °C. Soaking blanched vegetables for 24 h in a solution with NaCl and citric acid prior to processing improved microwave heating. Heating was non-uniform in all packages with a cold spot of approximately 60 °C at a point in the container farthest from the incident microwaves. More uniform heating was achieved by implementation of a two-stage rotation apparatus to rotate vegetable cups 180° during processing. Rotating the cups resulted in more uniform heating and a temperature of 77 °C at the cold spot. This is above the industrial standard of 74 °C for in-pack pasteurization of acidified vegetables. The effective treatment involved blanching, soaking for 24 h in a NaCl and citric acid solution, and 180° rotation. This work has contributed to a better understanding of the influence of salt addition and distribution during dielectric heating of acidified vegetables using a 915 MHz continuous microwave system.     

Antisense Peptide Technology for Diagnostic Tests and Bioengineering Research

Antisense peptide technology (APT) is based on a useful heuristic algorithm for rational peptide design. It was deduced from empirical observations that peptides consisting of complementary (sense and antisense) amino acids interact with higher probability and affinity than the randomly selected ones. This phenomenon is closely related to the structure of the standard genetic code table, and at the same time, is unrelated to the direction of its codon sequence translation. The concept of complementary peptide interaction is discussed, and its possible applications to diagnostic tests and bioengineering research are summarized. Problems and difficulties that may arise using APT are discussed, and possible solutions are proposed. The methodology was tested on the example of SARS-CoV-2. It is shown that the CABS-dock server accurately predicts the binding of antisense peptides to the SARS-CoV-2 receptor binding domain without requiring predefinition of the binding site. It is concluded that the benefits of APT outweigh the costs of random peptide screening and could lead to considerable savings in time and resources, especially if combined with other computational and immunochemical methods.     

Optimization of the UTC-PD Epitaxy for Photomixing at 340 GHz

We present a method to optimize the epitaxial layer structure of an InGaAs/InP uni-traveling-carrier photo-diode (UTC-PD) for continuous THz-wave generation. The design approach used is general in that it can be applied for any target frequency while this study focuses on 340 GHz. The photodiode epitaxy is modeled and optimized using a TCAD software implementing the hydrodynamic semiconductor equations. This physical device model was found to be in good agreement with reported experimental results. It is shown that the UTC-PD can generate ~1 mW at 340 GHz by choosing the optimum absorption layer and collection layer thicknesses.     

Spincopter Wing Design and Flight Control

This paper presents dynamical properties of an unmanned aerial vehicle (UAV), called spincopter. The vehicle structure is based on two wings that are forced in rotation (spinning) by propulsion system formed of two propellers. Based on devised dynamical model, that reveals inherent stability of the vehicle, composition of control algorithms for vertical and horizontal movement is proposed. Due to the specific configuration of the propulsion system, movement in horizontal direction is produced by pulsations in rotational speed of propulsion motors. An analysis of influence that such a configuration has on the vehicle dynamics is given. Finally, design recommendations for rotational wings are elaborated, based on extensive simulations of spincopter by using X-Plane® software package.     

Behavior of HSLA A709 steel under different environmental conditions

According to the requirement of the knowledge of material mechanical properties in structure design procedure, the paper considered experimentally obtained data regarding the high-strength low-alloy A 709 Gr50 steel. In that way, ultimate tensile strength and 0.2 offset yield strength at both lowered and elevated temperatures were presented and analyzed. The effect of temperature exerted on both of the mentioned strengths was presented. Creep responses for selected temperatures and selected stress levels were also considered. All of the tests are related to the uniaxial tensile tests and were performed in the laboratory of the Department for Engineering Mechanics at the Faculty of Engineering Rijeka.     

Open data and data sharing in articles about COVID-19 published in preprint servers medRxiv and bioRxiv

Scientometrics - This study aimed to analyze the content of data availability statements (DAS) and the actual sharing of raw data in preprint articles about COVID-19. The study combined a...     

The bounds on the solutions of certain two-dimensional delay dynamic systems on time scales

By means of a new linear Gronwall–Bellman inequality on time scales and an elementary inequality, the bounds on the solutions of a class of new nonlinear two-dimensional dynamic systems on time scales are obtained.     

Vacuum brazing of aluminium metal matrix composite (55 vol.% SiCp/A356) using aluminium-based filler alloy

Aluminium matrix composites with high volume fractions of SiC particles, as the reinforcements, are potentially suitable materials for electronic packaging. These composites, due to their poor weldability, however, have very limited applications. The microstructure and shear strengths of the bonds made in 55 vol.% SiC_p/A356 composite, using an aluminium based filler alloy containing Cu, Si, Mg and Ni, were investigated in this paper. The brazing temperature had a clear effect on the bond integrity, and the samples brazed at 560 °C demonstrated good bonding between the filler alloy and the SiC particles. The maximum shear strength achieved in this work was 102 MPa.     

A study of volatile flavour substances in Dalmatian traditional smoked ham: Impact of dry-curing and frying

Volatiles from Dalmatian prosciutto were isolated by solvent extraction (SE), simultaneous distillation extraction (SDE) and nitrogen purge and steam distillation (NPSD) and analyzed by GC and GC–MS. In all, 46 compounds were identified by SDE and SE (including fatty acids, aldehydes, phenols, esters, ketones and others), while 81 compounds were identified by NPSD (headspace volatiles including phenols, aldehydes, hydrocarbons, ketones, alcohols, esters and heterocyclic compounds). Regarding the impact of dry curing period on the volatiles, an increase in the percentages of aldehydes and esters during the ripening of the prosciutto was observed. Quantitative percentage differences among fried and raw samples were particularly evident in respect of aldehydes (SDE and SE). The NPSD method provided additional information of the volatiles from fried ham, since the pyrazines and most of the lower aldehydes that are important thermally derived flavour compounds were only isolated by NPSD (not by SE and SDE).