Bactericidal efficacy of slightly acidic electrolyzed water (SAEW) against Listeria monocytogenes planktonic cells and biofilm on food-contact surfaces

In the present study, the bactericidal efficacy of slightly acidic electrolyzed water (SAEW) against L. monocytogenes planktonic cells and biofilm on food-contact surfaces including stainless steel and glass was systematically evaluated. The results showed that SAEW (pH of 5.09 and available chlorine concentration (ACC) of 60.33 mg/L) could kill L. monocytogenes on food-contact surfaces completely in 30 s, whose disinfection efficacy is equal to that of NaClO solutions (pH of 9.23 and ACC of 253.53 mg/L). The results showed that long exposure time and high ACC contributed to the enhancement of the disinfection efficacy of SAEW on L. monocytogenes on food-contact surfaces. Moreover, the log reduction of SAEW treatment presented an increasing tendency within the prolonging of treatment time when SAEW was used to remove the L. monocytogenes biofilm formed on stainless steel and glass surfaces, which suggested that SAEW could remove L. monocytogenes biofilm effectively and its disinfection efficacy is equal to (in case of stainless steel) or higher than (in case of glass) that of high ACC of NaClO solutions. In addition, the results of the crystal violet staining and scanning electron microscopy (SEM) also demonstrated that SAEW treatment could remove the L. monocytogenes biofilm on food-contact surfaces.

Wear of Dry Sliding Al 6061-T6 Alloy Under Different Loading Conditions

In the present work, wear of Al 6061-T6 alloy under different normal loads, sliding speeds and temperatures was investigated. Pin on disk type tribometer was used to conduct dry sliding experiments. Different load combinations comprising of normal loads (1 kg, 1.5 kg and 2 kg), sliding speeds (1.25 m/s, 2 m/s and 3 m/s) and temperatures (room temperature (31 ± 1 °C), 60 °C, 100 °C and 150 °C) were applied during dry sliding experiments. Adhesive and abrasive wear mechanisms were observed in dry sliding of Al 6061-T6 alloy contacts from the microscopic analysis of worn contact surfaces. The wear rate was more influenced by increase in normal load than increase in sliding speed and temperature. Under normal loads of 1 kg and 1.5 kg, Al 6061-T6 alloy showed better wear resistance at higher temperatures when compared to that at room temperature.

Environmental and Fecal Indicator Organisms on Fruit Contact Surfaces and Fruit from Blueberry Mechanical Harvesters

Although previous studies have examined microbial loads on food contact surfaces in blueberry packing plants, there is currently no information regarding microbial risks associated with mechanical berry harvesters used in commercial blueberry production. In this study, we surveyed up to nine fruit contact surfaces on seven mechanical harvesters in each of 2015 and 2016 in the field. These surfaces included the shaking rods at the front of the harvester, the sidewalls of the harvesting tunnel behind the shaking mechanism, the catcher plates collecting the detached berries, horizontal and vertical fruit conveyor belts, and berry lugs collecting the fruit at the back of the harvester. Swab samples were collected from each surface three times a day (morning, noon, and evening) and assessed for environmental and fecal indicator organisms including total aerobes, total yeasts and molds, coliforms and fecal coliforms, and enterococci. At the same time points, fruit samples were assessed for microbial loads before the fruit entered each harvester and after they exited the harvester. Results showed statistically significant differences in microbial loads among harvester surfaces, whereas the effect of sampling time was generally not significant. High levels of total aerobes and total yeasts and molds were recorded, especially on horizontal surfaces and/or those located at the bottom of the harvester such as the lower sidewall, the catcher plates, and the horizontal conveyor belt. These surfaces therefore should be targeted by cleaning and sanitization practices. There was also statistical evidence that passage through the harvester may increase the levels of the environmental microorganisms on fruit in the field. In contrast, fecal indicator organisms such as fecal coliforms and enterococci were detected only sporadically and at very low densities on harvester surfaces and blueberry fruit, and there was no evidence that passage through the harvester increased their levels on the fruit. Berry lugs consistently harbored microbial loads, and given their movement back and forth between the field and the packing plant, deserve particular attention with regard to cleaning, sanitization, and storage protocols.

Evaluation of Salmonella Biofilm Cell Transfer from Common Food Contact Surfaces to Beef Products

Meat contamination by Salmonella enterica is a serious public health concern. Available studies have suggested that biofilm formation at processing plants and the contaminated contact surfaces might contribute to meat contamination. Since bacteria transfer from contact surfaces to food products via direct contact has been deemed as the most common transmission route that could lead to contamination, we evaluated the effect of Salmonella biofilm forming ability, contact surface materials, and beef surface tissue types on Salmonella biofilm transfer from hard surfaces to beef products. Salmonella biofilms developed on common contact surface stainless steel (S.S) and polyvinylchloride (P.V.C) were transferred consecutively via direct contacts of 30 sec each to either lean muscle or adipose tissue surfaces of 15 pieces of beef trim. Our results showed that Salmonella biofilm cells could be effectively transferred multiple times from contact surface to beef trim as enumerable Salmonella cells could be detected on most of the meat samples. Bacterial biofilm forming ability had the most significant impact (p<0.05) on transfer efficiency as the strong biofilm forming strains not only transferred higher amounts of bacteria after each contact, but also contaminated more meat samples with enumerable Salmonella cells compared to the weak biofilm formers. Contact surface materials could affect transferability as Salmonella biofilms on S.S surface appeared to transfer more efficiently compared to those on P.V.C surface. Conversely, the two types of meat surface tissues showed no significant difference (p>0.05) on biofilm transfer efficiency. Furthermore, biofilm - contacted beef trim without enumerable Salmonella cells all exhibited positive Salmonella prevalence after enrichment. Our study demonstrated the high potential of Salmonella biofilms on common contact surfaces to cause product cross contamination in meat processing plants.

Influence of ultrasonic agitation on the abrasive wear characteristics of Al-Cu/ 2 vol.% Grp composite

In the present study, the abrasive wear behavior of Al-4.4 wt.% Cu composite reinforced with 2 vol.% graphite particle (Grp) has been investigated. In the preparation of composite, Ultrasonic Treatment (UT) is provided in the composite melt for the uniform distribution of reinforcement particles. Two bond abrasive wear tests are conducted for composites treated with ultrasound and without UT and base alloy. The results of abrasive wear studies indicate that at 5 and 10 Newton (N) loads, the composite with UT has a higher coefficient of friction (COF) and wear resistance than that of the base alloy (Al-4.4 wt.% Cu). Whereas, at 15 and 20 N load, the value of COF and wear resistance is lower for the composite. Two abrasive wear mechanisms micro-plowing and micro-cutting have been observed during the wear tests of base alloy and composites. The analysis of worn-out sample surfaces at higher load reveals that softened material layer due to localized elevation in temperature between two contact surfaces during wearing acts as a tribolayer in base alloy while in composites both softened material layer and graphite layer have worked together as tribolayer.

Methods for increasing the wear resistance of heavy loaded metal-polymer tribosystems

Methods of increasing the wear resistance and reliability of friction units are generating considerable interest being a vital factor in transport, mechanical engineering, and other fields of technology. The solution of the given problem is impossible without the creation of self-regulating structures on the friction contact surfaces. We strongly believe that this problem can be solved by creating multicomponent functional layers (hereafter MFL) on tribocontact.

Autonomous identification of high-contact surfaces from convolutional neural networks

The rapid spread of the SARS-CoV-2 virus has highlighted many social interaction problems that favor the spread of disease, particularly airborne spread, which can be addressed by adjusting existing systems. Of particular interest are places where large numbers of people interact, as they become a focus for the spread of these diseases. This paper proposes and evaluates an autonomous identification scheme for certain surfaces considered high risk due to their continuous handling. These high-contact surfaces can be identified by an autonomous system to apply specific cleaning tasks to them. We evaluate three convolutional models from a proprietary dataset with a total of 2000 images ranging from wall switches to water dispensers. The objective is to identify the ideal architecture for the system. The ResNet (Residual Neural Network), DenseNet (Dense Convolutional Network), and NASNet (Neural Architecture Search Network) models were selected due to their high performance reported in the literature. The models are evaluated with specialized metrics in non-binary classification problems, and the best scheme is selected for prototype development.

A CASE STUDY ABOUT DEGRADATION OF THE BUILDINGS AND THEIR BUILDINGELEMENTS AS A RESULT OF CLIMATE CHANGE

The article deals with the problems of climate change and global warming, extreme climate phenomena, which present risk factors for the national economy, including construction. The causes that lead to the occurrence of the construction degradation phenomena are diverse and may be specific to improper exploitation, but also as a consequence of extraordinary natural phenomena or results from the humanity’s interrelationship with the environment. The degradation of the constructions is manifested by the gradual loss of the physical and functional qualities that characterize the aptitude for their exploitation, the degradation process manifesting itself starting from the contact surfaces of the constructions with the environment. Urban planning and the design of adequate infrastructure play an important role in minimizing the impact of climate change and reducing the risk to the human environment. The undertaking's measures, which will consider the potential impact of climate change on buildings, will provide opportunities for new markets for climate change-resistant technologies, machinery, materials, and products