A critical review on biodegradable food packaging for meat: Materials,sustainability, regulations,and perspectives in the EU

The development of biodegradable packaging is a challenge, as conventional plastics have many advantages in terms of high flexibility, transparency, low cost, strong mechanical characteristics, and high resistance to heat compared with most biodegradable plastics. The quality of biodegradable materials and the research needed for their improvement for meat packaging were critically evaluated in this study. In terms of sustainability, biodegradable packagings are more sustainable than conventional plastics; however, most of them contain unsustainable chemical additives. Cellulose showed a high potential for meat preservation due to high moisture control. Polyhydroxyalkanoates and polylactic acid (PLA) are renewable materials that have been recently introduced to the market, but their application in meat products is still limited. To be classified as an edible film, the mechanical properties and acceptable control over gas and moisture exchange need to be improved. PLA and cellulose-based films possess the advantage of protection against oxygen and water permeation; however, the addition of functional substances plays an important role in their effects on the foods. Furthermore, the use of packaging materials is increasing due to consumer demand for natural high-quality food packaging that serves functions such as extended shelf-life and contamination protection. To support the importance moving toward biodegradable packaging for meat, this review presented novel perspectives regarding ecological impacts, commercial status, and consumer perspectives. Those aspects are then evaluated with the specific consideration of regulations and perspective in the European Union (EU) for employing renewable and ecological meat packaging materials. This review also helps to highlight the situation regarding biodegradable food packaging for meat in the EU specifically.     

The effect of heat transfer characteristics of macromolecule fouling on heat exchanger surface: A dynamic simulation study

At the city gate gas pressure reduction stations (CGSs), to prevent natural gas from forming a hydrate in the throttle valve, the natural gas is heated by the heater before reaching the pressure relief valve. Heat exchangers are an essential component of industrial processes that contribute significantly to total system energy. Since the element impacting heat exchanger performance is the fouling process, all fouling processes and models were dynamically simulated in this study. Through coding in the C++ language and simultaneous use of fluent functions, or, in other words, user-defined function (UDF), fouling-related models were defined for this software. The dynamic simulation was performed, and parameters such as fouling strength and layer thickness were calculated. The effects of changing operating conditions, such as gas inlet velocity, surface temperature, and fouling species concentration on fouling growth, were also evaluated. As the concentration of fouling species increased, the fouling rate also increased. The amount of supersaturation and fouling rate increased as the surface temperature increased. Due to the operational limitations of the system, to reduce the fouling rate, the gas inlet velocity should be as high as possible, and the fluid inlet temperature, surface temperature, and concentration of fouling species should be as low as possible. In this study, the required time to reach the efficiency of 70% of the heat exchanger was calculated using the modelling of this chamber, which was equivalent to 190 days. Additionally, the critical thickness of the fouling layer at this time was 3.5 cm.     

Observer-based event-triggered H-infinity sliding control of Markovian jump system suffer from actuator attacks

This article investigates the issue of observer-based $H_{\infty }$ sliding mode control for Markovian jump systems suffer from actuator attacks through an adaptive technique. During the communication channel from the plant output to estimator, a dynamic event-triggered generator is employed in enhancing communication efficiency. Taking consideration of malicious attacks on the plant actuator, an adaptive compensator is put forward for security purposes. By designing a state observer, the desired sliding mode dynamics can be derived based on an integral-type sliding surface. Further, maintaining the sliding motion with uncertain mode information is ensured in finite time by proposing a feasible sliding mode control law. In addition, both stochastic stability and $H_{\infty }$ performance conditions are established for closed-loop systems in terms of linear matrix inequalities. Finally, a numerical example is offered to illustrate the validity of the constructed strategy.     

Dual-drug delivery of sodium ceftriaxone and metronidazole by applying salt-assisted chitosan nanoparticles: Stability,drug release,and time-kill assay study against Bacteroides fragilis

The purpose of this study was to develop a polymeric biomaterial with regulated dual drug release and increased bactericidal strength of the antibiotics sodium ceftriaxone (CTX) and metronidazole (MTZ) for the treatment of intra-abdominal infections. Chitosan nanoparticles (CS NPs) were produced by ionic crosslinking process in the presence of NaCl monovalence salt. The antibacterial activity and drug release behavior of CS NPs were investigated against anaerobic Bacteroides fragilis. The optimum initial drug ratio for designing dual drug carriers containing CTX and MTZ in a 4:3 ratio was 1:1. After 6 months, the salt-assisted CTX-MTZ-loaded CS NPs were 300 nm in size and had a polydispersity index of 0.09 with high stability. It has been demonstrated that drug release from NPs is more tightly controlled than drug release from free drugs. Furthermore, the data show that the minimum inhibitory concentration and minimum bactericidal concentration for nanostructure carriers are one-quarter of those of free medicines. Free drugs could completely kill the bacterium after 24 h, but the dual drug carrier could kill the bacteria in 10 h. Finally, salt-assisted CTX-MTZ-loaded CS NPs were proposed as a feasible alternative to standard intra-abdominal infection treatment.     

Comparison the properties of PVA/Na+‐MMT nanocomposite hydrogels prepared by physical and physicochemical crosslinking

A novel physicochemical crosslinked nanocomposite hydrogel based on polyvinyl alcohol (PVA) and natural Na‐montmorillonite (Na⁺‐MMT) was synthesized by chemical crosslinking of nanocomposite hydrogel followed by a freezing‐thawing process. The effects of physical crosslinking, as well as physicochemical crosslinking, on the structure, morphology, and properties (thermal, mechanical, swelling, and deswelling) of nanocomposite hydrogels were investigated and compared with each other. The structure and morphology of nanocomposites were studied by Fourier transform infrared, X‐ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy techniques. The thermal and mechanical properties of nanocomposites that were affected by physical and physicochemical crosslinking were evaluated by thermogravimetric analysis, differential scanning calorimeter, dynamic mechanical analysis, hardness test, and Water vapor transmission rate (WVTR) experiments. The results showed that the physicochemical crosslinking of a PVA nanocomposite leads to a reduction in crystallinity and melting temperature, as well as an increase in the Hardness and WVTR compared to a physically crosslinked PVA nanocomposite hydrogel. The swelling and deswelling experiments were performed using a gravimetric method, and it was shown that controlled crosslinking of PVA nanocomposite hydrogel with glutaraldehyde causes the swelling ratio to increase and the cumulative amount of water loss to decrease. The swelling (sorption) and deswelling (desorption) kinetics data for physically and physicochemical crosslinking of nanocomposite hydrogels were fitted with a fickian model. It is concluded that through control crosslinking of PVA nanocomposite can lead to a hydrogel with higher swelling capacity than that is in conventional PVA nanocomposite hydrogel. POLYM. COMPOS., 37:897–906, 2016. © 2014 Society of Plastics Engineers     

Exact analytical solution of forced convection through a porous-saturated duct

In the current paper, the effect of a magnetic field on the fully developed forced convective flow and heat transfer is studied. An exact solution is extracted when the flow in the porous medium is governed by the Brinkman–Forchheimer Extended Darcy model. First, the problem formulation is explained to obtain a new system of mathematical formulation. Then, by utilizing the properties which are imposed into the problem, the exact closed-form analytical solution of the problem is explored. Finally, the main results are illustrated to show the impact of the porous media-shaped parameter, magnetic parameter, Forchheimer number, and viscosity ratio. It should be mentioned that the asymptotic results achieved in this study were compared with the exact results and it is found that they are in good agreement.     

Improved Cytotoxicity and Induced Apoptosis in HeLa Cells by Co-loading Vitamin E Succinate and Curcumin in Nano-MIL-88B-NH2

One of the strategies for improved therapeutic effects in cancer therapy is combination chemotherapy. In this study, a flexible nano-MOF (Fe-MIL-88B-NH₂) was synthesized in a sonochemical process, then co-loaded with α-tocopheryl succinate (TOS) and curcumin (CCM). The anticancer activity of co-loaded Fe-MIL-88B-NH₂ (Fe-MIL-88B-NH₂/TOS@CCM) against the HeLa cells was compared with that of the single-loaded counterpart (Fe-MIL-88B-NH₂@CCM). MTT analysis indicates improved cytotoxicity of Fe-MIL-88B-NH₂/TOS@CCM. The data from the cell apoptosis assay indicated more apoptosis in the case of the co-loaded nano-MOF. This study indicates the positive effect of the presence of TOS on enhancing the anticancer effect of Fe-MIL-88B-NH₂@CCM to prepare a more efficient drug delivery nanosystem.     

Analysis of interaction effects of persulphate and peroxymonosulphate on solar photocatalytic degradation of cortisone acetate

The degradation of environmental contaminants using sustainable solar energy is one of the most promising applications of the photocatalytic process. In this research, the individual and interaction effects of persulphate (PS) and peroxymonosulphate (PMS) oxidants on the solar photocatalytic degradation of cortisone acetate (CA) were studied. Concentrations of PS, PMS, and photocatalyst were independent variables, and the response was CA degradation efficiency. Response surface methodology (RSM) and artificial neural network (ANN) models were developed to predict the CA degradation efficiency. The analysis of the current results revealed that the optimum amounts of individual variables were highly affected by the other variables, which confirmed their significant interaction effect. As an example, by increasing the PS concentration, not only were the required concentrations of PMS and photocatalyst decreased, but also the degradation efficiency was enhanced. Then, the overall optimum concentration of the photocatalyst, PS, and PMS were found to be respectively 328.7, 119.1, and 194.2 mg/L using the genetic algorithm method. The maximum CA degradation efficiency at the optimum condition was 95.6% after only 30 min of solar radiation. Finally, investigation of relative importance of the variables showed that the concentrations of both oxidants affected the degradation efficiency almost equally.