Risks and new challenges in the food chain: Viral contamination and decontamination from a global perspective,guidelines, and cleaning

Even during the continuing world pandemic of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2), consumers remain exposed to the risk of getting infected by existing, emerging, or re-emerging foodborne and waterborne viruses. SARS-CoV-2 is different in that it is transmitted directly via the airborne route (droplets and aerosols) or indirect contact (surfaces contaminated with SARS-CoV-2). International food and health organizations and national regulatory bodies have provided guidance to protect individuals active in food premises from potential occupational exposure to SARS-CoV-2, and have recommended chemicals effective in controlling the virus. Additionally, to exclude transmission of foodborne and waterborne viruses, hygiene practices to remove viral contaminants from surfaces are applied in different stages of the food chain (e.g., food plants, food distribution, storage, retail sector, etc.), while new and enhanced measures effective in the control of all types of viruses are under development. This comprehensive review aims to analyze and compare efficacies of existing cleaning practices currently used in the food industry to remove pathogenic viruses from air, nonfood, and food contact surfaces, as well as from food surfaces. In addition, the classification, modes of transmission, and survival of food and waterborne viruses, as well as SARS-CoV-2 will be presented. The international guidelines and national regulations are summarized in terms of virucidal chemical agents and their applications.     

Hot deformation characteristics of 2205 duplex stainless steel based on the behavior of constituent phases

High temperature behavior of 2205 duplex stainless steel was studied by considering behavior of each constituent phase. The specimens were subjected to hot compression tests at temperatures of 800–1100 °C and strain rates ranging from 0.001 to 1 s⁻¹ at intervals of an order of magnitude. The flow stress analysis showed that hot working empirical constants are different at low and high temperatures. The strain rate sensitivity m was determined and found to change from 0.12 to 0.21 for a temperature rise from 800 °C to 1100 °C. The apparent activation energy Q was calculated as 554 and 310 kJ/mol for low and high temperature, respectively. The validity of constitutive equation of hyperbolic sine function was studied and stress exponent, n, was assessed to be 4.2. Assuming the hyperbolic sine function for determination of strain rate and application of the rule of mixture, the interaction coefficients of δ-ferrite, P, and austenite, R, were estimated at different hot working regimes. It was found that the interaction coefficients are functions of Zener–Hollomon parameter Z and obey the formulas P = 1.4Z^−0.08 and R = 0.76Z^0.005. Therefore, it was concluded that at low Z values δ-ferrite almost accommodates strain and dynamic recovery is the prominent restoration process which may even inhibit dynamic recrystallization in austenite. Otherwise, at high Z, austenite controls the deformation mechanism of material and dynamic recrystallization leads in finer microstructure.     

A kinetic study on the electrophoretic deposition of hydroxyapatite–titania nanocomposite based on a statistical approach

In the present study, the electrophoretic deposition (EPD) process of hydroxyapatite–titania nanocomposite was kinetically described by the use of response surface methodology (RSM). The electrostatic interaction between particles in ethanol based suspensions was determined by Zeta potential and particle size analyses. After successful electrophoretic deposition from hydroxyapatite–titania suspensions with 0, 10 and 20 wt% of titania nanoparticles, it was shown that Baldisserri model can well reproduce the experimental data among the other semi-empirical kinetic equations. The as-deposited hydroxyapatite–titania nanocomposites were characterized employing SEM, AFM, XRD, and FT-IR analyses. Then, the effects of deposition voltage, deposition time and wt% TiO₂ on the kinetic of EPD at two time intervals (10–60 s and 60–300 s) were identified and quantified via RSM based on a central composite design (CCD). According to the results obtained from the statistical analysis, it was found that the deposition rate decreases by an increase in wt% TiO₂ and time. Also, a transition in deposition mechanism from linear to parabolic mode was observed and two second order polynomial equations were fitted to the response (deposit weight) at each time intervals.     

The effect of pH on the interaction between Eu3 + ions and short single-stranded DNA sequence,studied with electrochemical,spectroscopic and computational methods

For the first time, interaction of short single-stranded DNA (ssDNA) sequence with Eu^3 + was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and UV–vis spectroscopy. The results show that interaction between Eu^3 + ions and ssDNA is related to solution pH and pK_a of ssDNA bases and have different binding mode at different pHs. It's clear that, at pH 3.7, only phosphate groups of ssDNA can interact with Eu^3 + ions, because in this pH ssDNA bases are totally protonated. But at higher pH (5.5), some of ssDNA bases can interact with Eu^3 + ions, too. Computational studies were done and confirm the result of experimental data. The agreement mutually verifies the accuracy of the methods.     

A ceria NPs decorated graphene nano-composite sensor for sulfadiazine determination in pharmaceutical formulation

Since the importance of sulfonamide compound determinations, in this work, Sulfadiazine (SDZ), one of the significant sulfonamide antibiotics was electrochemically studied. SDZ is listed as world health organization (WHO) crucial medications in treatment of basic health system. A new graphene based nano-composite electrode was made and used for the electrochemical studies of some sulfondiamides. Electrochemical behavior of the compounds was initially investigated on bare and modified carbon paste electrodes using cyclic voltammetry (CV). The modifiers include Ceria (CeO₂) NPs, reduced graphene oxide (RGO) and RGO decorated CeO₂ NPs. The composition of 5% RGO decorated CeO₂ nanoparticles, 65% graphite, and 30% paraffin presented the best redox response for Sulfadiazine. Then, the nano-composite electrode was applied for SDZ measurement by fast Fourier transform square wave voltammetry (FFTSWV) on the proposed nano-composite electrode. Response linear range was obtained for 3–10 µM (R²?=?0.9956) and 30–1000 µM (R²?=?0.9948) of SDZ concentration, respectively, with LOD of 0.17 µM and LOQ of 3 µM. Finally, SDZ content in some pharmaceutical formulations were effectively analyzed by the proposed method and acceptable relative error of 4.6% was achieved.     

Ho3+ carbon paste sensor based on multi-walled carbon nanotubes: Applied for determination of holmium content in biological and environmental samples

For the first time a novel multi-walled carbon nanotubes (MWCNTs) modified Ho³⁺ carbon paste sensor is introduced. The electrode with a composition containing 20% paraffin oil, 60% graphite powder, 15% N-(1-thia-2-ylmethylene)-1,3-benzothiazole-2-amine (TBA) as an ionophore, and 5% MWCNTs, exhibits a stable potential response to Ho³⁺ ions with a nice Nernstian behavior (19.3 ± 0.3 mV decade^? 1) in a wide dynamic linear concentration range of Ho³⁺ ions (1 × 10^? 8–1.0 × 10^? 2 M). In the absence of MWCNTs, sensitivity of the Ho³⁺ sensor was relatively poor. The proposed modified Ho³⁺ sensor shows very low detection limit (7.0 × 10^? 9 M) and a fast response time (13 s). It has a long life time (more than 2 months) and its response is independent of pH in the range of 3.8–7.5. In term of selectivity, Ho³⁺ sensor has a good selectivity over all lanthanide members and common alkali and alkaline earth metal ions. The Ho³⁺ sensor was applied for the determination of Ho³⁺ ion concentration in water, holmium alloys and synthetic human serum.     

Voltammetric determination of venlafaxine as an antidepressant drug employing Gd2O3 nanoparticles graphite screen printed electrode

Graphite screen printed electrode modified with Gd_2 O_3 nanoparticles(Gd_2 O_3/SPE) was developed for the determination of venlafaxine(VF). The Gd_2 O_3 nanoparticles were thoroughly characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and X-ray diffraction(XRD) analyses. To study the electrochemical behaviour of venlafaxine cyclic voltammetry(CV), chronoamperometry(CHA)and differential pulse voltammetry(DPV) were employed. These studies reveal that the oxidation of venlafaxine is facilitated at Gd_2 O_3/SPE. After optimization of analytical conditions, analysis of venlafaxine using the modified electrode in 0.1 mol/L PBS(pH 7.0) demonstrates that the peak currents corresponding to venlafaxine vary linearly with its concentration in the range of 5.0 ×10~(-6)-9.0 × 10~(-4) mol/L. The detection limit(S/N = 3) of 2.1 × 10~(-7) mol/L is obtained for venlafaxine using DPV. The prepared modified electrode benefits from advantages such as simple preparation method, high sensitivity and low detection limit.Moreover, the evaluation of practical applicability of this proposed method is successful in the identification of venlafaxine in pharmaceutical formulations, urine and water samples.     

Novel erbium (III)-selective fluorimetric bulk optode

For the first time a highly sensitive and selective fluorimetric optode membrane was prepared for the determination of trace amounts of Er(III) ions. The Er(III) sensing system was constructed by incorporating 5-(dimethylamino) naphthalene-1-sulfonyl-4-phenylsemicarbazide (L) as a neutral Er(III)-selective fluoroionophore, in the plasticized PVC-membrane containing sodium tetraphenyl borate as a lipophilic anionic additive. The response of the optode is based on the strong fluorescence quenching of L by Er³⁺ ions. At a pH value of 5.0, the proposed optode displays a wide concentration range of 1.0 × 10⁻¹⁰ to 1.0 × 10⁻² M, with a relatively fast response time of less than 50 s. In addition, to high stability and reproducibility, the sensor shows a unique selectivity towards Er³⁺ ion with respect to common cations. The proposed optode was applied successfully to the trace determination of erbium ion in binary mixture and water samples.     

Application of 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea as sensing material for construction of Tm3+-PVC membrane sensor

A thulium(III) membrane sensor was made using 2% sodium tetraphenyl borate (NaTPB), 65% dibutylphthalate (DBP), 30% poly(vinyl chloride) (PVC) and 3% 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea (ET) as an ionophore. Conductometric study shows selectivity of the Et toward Tm³⁺ ions. Nernstian response of 19.6 ± 0.4 mV per decade of thulium concentration was observed, and the electrode worked well in concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a lower detection limit (LDL) of 7.2 × 10^? 7 mol L^? 1, in a pH range of 4.3–10.4. The selectivity of the sensor over alkaline, alkaline earth, transition and heavy metal ions was also found to be in a satisfactory range. To check the analytical applicability of the proposed Tm³⁺ sensor, it was successfully used as an indicator electrode in analysis of thulium in certified reference materials.     

Cell Surface Display of Salmonella Outer Membrane Protein A on Lactobacillus salivarius: A First Step Towards Food-Grade Live Vaccine Against Salmonella Infections

As one of the most important pathogens in both humans and animals, Salmonella is a significant health problem, especially in the developing countries. Outer membrane protein A (OmpA) is among the major outer membrane proteins of Salmonella with strong immunogenicity. Vaccination is an effective tool for the prevention of Salmonella infections. Lactic acid bacteria are the normal flora of gastrointestinal (GI) tract. In this research, lactobacilli from different parts of chicken GI tract were isolated and evaluated for bile salts and acidic pH tolerance. One strain isolated from the small intestine was identified as Lactobacillus salivarius by carbohydrate fermentation test and 16SrRNA partial sequencing. To address the need for safe oral vaccine to control Salmonella infection, we engineered this natural chicken isolate of L. salivarius to express OmpA under promotion of Lactate dehydrogenase (ldh) promoter. The surface displayed OmpA reacted with anti-OmpA in ELISA, Immunoblotting and flow cytometry assays, suggesting that the expressed protein adopted a native conformation. Strong agglutination reaction of the recombinant lactobacilli with sera of the naturally Salmonella infected chickens showed the multivalency and overexpression of the OmpA on the surface of L. salivarius. Experimental infection assay confirmed that the engineered commensal bacteria could be an attractive candidate as food-grade live vaccine against Salmonella infections.