Microstructural and Tribological Properties of A356 Al–Si Alloy Reinforced with Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Particles

In the present study, the effect of the Al₂O₃ particles (average size of 12 μm, 3 and 10 wt.%) reinforcement on the microstructure and tribological properties of Al–Si alloy (A356) was investigated. Composites were produced by applying compocasting process. Tribological properties of unreinforced alloy and composites were studied, using pin-on-disc tribometer, under dry sliding conditions at different specific loads and sliding speed of 1 m/s. Microhardness measurements, optical microscope and scanning electron microscope were used for microstructural characterization and investigation of worn surfaces and wear debris. During compocasting of A356 alloy, a transformation from a typical dendritic primary α phase to a non-dendritic rosette-like structure occurred. Composites exhibited better wear resistance compared with unreinforced alloy. Presence of 3 wt.% Al₂O₃ particles in the composite material affected the wear resistance only at specific loads up to 1 MPa. The wear rate of composite with 10 wt.% Al₂O₃ particles was nearly two order of the magnitude lower than the wear rate of the matrix alloy. Dominant wear mechanism for all materials was adhesion, with others mechanisms: oxidation, abrasion and delamination as minor ones.     

Brewers' spent grain and thin stillage as raw materials in l‐(+)‐lactic acid fermentation

Brewer's spent grain (BSG) hydrolysates were used for l ‐(+)‐lactic acid (LA) fermentation by Lactobacillus rhamnosus ATCC 7469. In this study the effect of the addition of various amounts of thin stillage (TS) in BSG hydrolysate on LA fermentation parameters were evaluated. TS addition significantly increased utilization of glucose by up to 43.0%. In batch fermentation the highest LA concentration and volumetric productivity of 31.0 g/L, and 0.93 g/L/h, respectively, were obtained with the addition of 50% TS. L. rhamnosus cell viability also increased with the addition of 50% TS (by 2.4%). TS addition significantly increased free amino nitrogen concentration (by up to 209%) which is important for bacterial growth. A strong positive correlation between free amino nitrogen and LA concentration was noted. Compared with the results obtained in the batch fermentation (50% TS), significantly higher LA concentration, yield and volumetric productivity (54.8, 1.9 and 4.0%, respectively) were achieved in fed‐batch fermentation with glucose and TS addition. The results suggest that the combination of the by‐products of brewing and bioethanol industries could be suitable for LA production. Copyright © 2017 The Institute of Brewing & Distilling     

Influence of T4 Heat Treatment on Tribological Behavior of Za27 Alloy Under Lubricated Sliding Condition

The effects of heat treatment on the microstructure, hardness, tensile properties, and tribological behavior of ZA27 alloy were examined. The alloys were prepared by conventional melting and casting route. The heat treatment of samples included the heating up to 370 °C for 3 or 5 h, quenching in water, and natural aging. Lubricated sliding wear test were conducted on as-cast and heat-treated ZA27 samples using block-on-disc machine. The friction and wear behavior of alloys were tested in contact with steel discs using combinations of three levels of load (10, 30, and 50 N) and three levels of linear sliding speeds (0.26, 0.50, and 1.00 m/s). To determine the wear mechanisms, the worn surfaces of the samples were examined by scanning electron microscopy (SEM). The heat treatment resulted in reduction in the hardness and tensile strength but increase in elongation. The heat-treated alloy samples attained improved tribological behavior over the as-cast ones, under all combinations of sliding speeds and contact loads. The rate of improvement increased with duration of solutionizing process before quenching in water. Obtained tribological results were related to the effects of heat treatment on microstructure changes of alloy.     

How do culinary methods affect quality and oral processing characteristics of pork ham?

The influences of three different culinary methods: cooking, sous vide and grilling were studied with regards to quality and oral processing characteristics of pork ham. Besides instrumental analysis of color and textural properties of pork ham, sensory panel with 12 trained panelists participated in temporal dominance of sensations, oral processing analysis, boluses collection, particle size distribution analysis, and saliva incorporation. The results revealed that number of chews, mastication time and saliva incorporation are correlated with textural properties and cooking losses. In‐mouth sensation was intertwined with juiciness, fibrousness and firmness depending on the culinary methods. Cooked pork ham showed highest results for hardness and cooking loss. Firmness and fibrousness were dominant sensory attributes. Sous‐vide results show that firmness and juiciness dominated during the first third of consumption time. This corresponds with textural values for lowest values for hardness and cooking, number of chews and total exposure time. Sous‐vide also resulted in lower values for number of chews and total exposure time associated with oral processing.     

Effectiveness of wheat-applied contact insecticides against Sitophilus granarius (L.) originating from different populations

Toxicity parameters were determined for granary weevil Sitophilus granarius adults in the laboratory after treatment of wheat grains with several contact insecticides: dichlorvos, malathion, chlorpyrifos-methyl, pirimiphos-methyl, deltamethrin, and deltamethrin with the piperonyl butoxide (PBO) synergist. The impact was determined on three populations: an insecticide-susceptible laboratory population, a population originating from Belgrade Port (Serbia) selected once previously with pirimiphos-methyl at the LD₇₀ level, and one from Bijeljina (Bosnia and Herzegovina) selected once at the LD₇₀ level with deltamethrin.

After exposure of granary weevil adults to treated wheat for 48 h, deltamethrin with PBO was the most effective insecticide against the laboratory population (LD₅₀=0.10 mg/kg and LD₉₅=0.25 mg/kg) and dichlorvos the least effective (LD₅₀=1.80 mg/kg and LD₉₅=5.35 mg/kg). Regarding the selected weevils from Belgrade Port and Bijeljina, the most effective insecticide was chlorpyrifos-methyl (LD₅₀=0.25 and 0.22 mg/kg; LD₉₅=0.40 and 0.28 mg/kg, respectively), and the least effective was dichlorvos (LD₅₀=6.56 and 4.99 mg/kg; LD₉₅=26.78 and 16.14 mg/kg).

Insecticide minimum effective doses (MED) able to prevent an F₁ or F₂ generation were determined. Deltamethrin+PBO had the lowest (0.2 mg/kg) and malathion the highest MED (>5.0 mg/kg) in both generations of laboratory weevils. The lowest MED for the selected weevils from Belgrade Port was recorded for deltamethrin+PBO (0.5 mg/kg for the F₁ and 0.3 mg/kg for the F₂ generation) and the highest for dichlorvos (6.0 mg/kg for both generations); while the lowest MED for the selected Bijeljina weevils was achieved by chlorpyrifos-methyl (0.3 mg/kg for the F₁ and 0.2 mg/kg for the F₂ generation) and the highest by malathion and dichlorvos (5.0 mg/kg) in the F₁ generation, and malathion (3.0 mg/kg) in the F₂ generation.     

Laboratory assessment of insecticidal effectiveness of natural zeolite and diatomaceous earth formulations against three stored-product beetle pests

The insecticidal effectiveness of two natural zeolite formulations (Minazel plus and Minazel), applied to wheat at selected rates of 0.25, 0.50 and 0.75 g/kg, and a diatomaceous earth formulation (DE) (Protect-It™), applied at the recommended rates of 0.15 g/kg for Sitophilus oryzae, 0.20 g/kg for Rhyzopertha dominica and 0.30 g/kg for Tribolium castaneum, were tested under laboratory conditions (24 ± 1 °C temperature and 45 ± 5% relative humidity). The highest adult mortality was observed after the longest exposure period of 21 days and 7 days of recovery, when all three zeolite dosage rates and the recommended DE dosage caused 97-100% mortality of S. oryzae and 94-100% of T. castaneum. On the other hand, 100% mortality was not achieved in any test variant involving R. dominica; the highest (about 92%) was detected for DE, while 52% and 79% mortality was achieved with the zeolites at the highest rate of 0.75 g/kg. Progeny reduction by >90% was achieved after 21 days of contact of all three beetle pests with DE-treated wheat, while the same level of reduction was achieved for S. oryzae and T. castaenum only after contact with the highest rate of the zeolite product, Minazel. Thus the two zeolite formulations are comparable to diatomaceous earth in controlling adult S. oryzae, R. dominica and T. castaneum, but only the Minazel formulation could effectively protect wheat from attack by S. oryzae or T. castaneum, and only with a higher rate of application than for the DE formulation.     

A decade of sulphite control in Serbian meat industry and the effect of HACCP

In total 7351 meat preparations and fresh processed meat products were analysed from 555 different Serbian meat producers over a 10-year period, 4.5 years before and 5.5 years after mandatory Hazard Analysis and Critical Control Points (HACCP) implementation. From the obtained results, it could be concluded that HACCP has contributed to a better alignment of practices with the legal provisions. The share of non-compliant samples dropped from 18.6% before HACCP to 8.3% after its mandatory implementation. Average sulphite concentrations for all categories of meat preparations and fresh processed meat products decreased by 43%, declining from 33.6 to 19.3 mg kg^?1. Typical misuse and frequent abuse of sulphites was independent of a season. Application of HACCP principles in the Serbian meat industry raised awareness about the misuse of sulphites and contributed to a better control, minimising exposure to sulphites.