Experimental study of lateral pass width in conventional and vibrations-assisted ball burnishing

Burnishing is a mechanical finishing operation performed on workpieces to enhance their surface quality through plastic deformation. One of the main issues to understand the overall process is the behavior of the elastoplastic deformations caused by the burnishing ball on the workpiece. The first burnishing passes performed on the workpiece surface lead to its plastic strain and self-hardening, thus influencing the results of consecutive passes. Some references have studied the phenomenon of indentation, finding that there is a certain self-hardening coefficient threshold which allows to predict the presence of pile-ups at the edges of the indentation path. Nevertheless, burnishing is not a single-pass operation. On the contrary, burnishing a whole surface requires successive adjacent and/or overlapping passes, i.e., parallel passes separated consecutively a certain lateral pass width. No reference has been found in the literature defining the adequate values of the lateral pass width with regards to the pile-up effect to enhance the final topology of the burnished surface. This paper explores that influence by studying the presence of the pile-up effect after burnishing a single or several overlapping passes on two materials (aluminum and steel), by characterizing the topology of the generated path. Afterwards, two adjacent passes are performed, varying the lateral pass width, to compare the final surface roughness derived from each operation. An optimum value for the lateral pass width was found, to improve the final roughness after burnishing in different conditions and to increase the productivity of the process.     

Reverse osmosis concentration of press liquid from orange juice solid wastes: Flux decline mechanisms

Orange juice production produces high amount of solid waste. An alternative for these wastes is their pressing with lime to obtain a press liquor stream and a dried solid for cattle feeding. The press liquor (around 10 °Brix) is traditionally concentrated up to 70 °Brix (citrus molasses) by multiple effect evaporation. In this investigation, reverse osmosis is evaluated as an alternative for press liquor preconcentration. Two synthetic feed solutions were studied, one included pectin in its composition (WP) and the other lacked pectin (WOP) to simulate a previous depectinization of WP. The concentration process was evaluated in terms of some selected parameters (chemical oxygen demand, total soluble solids, total dissolved solids and osmotic pressure). The fouling mechanism as well as the membrane resistance to the permeate pass were assessed. It was found that for later stages of concentration cake filtration was the dominant fouling mechanism while for earlier stages, the mechanism found was the complete pore blocking. The presence of pectin not only maximized the membrane fouling but also led to worse permeate quality.     

TCR Recognition of Peptide–MHC-I: Rule Makers and Breakers

T cells are a critical part of the adaptive immune system that are able to distinguish between healthy and unhealthy cells. Upon recognition of protein fragments (peptides), activated T cells will contribute to the immune response and help clear infection. The major histocompatibility complex (MHC) molecules, or human leukocyte antigens (HLA) in humans, bind these peptides to present them to T cells that recognise them with their surface T cell receptors (TCR). This recognition event is the first step that leads to T cell activation, and in turn can dictate disease outcomes. The visualisation of TCR interaction with pMHC using structural biology has been crucial in understanding this key event, unravelling the parameters that drive this interaction and their impact on the immune response. The last five years has been the most productive within the field, wherein half of current unique TCR–pMHC-I structures to date were determined within this time. Here, we review the new insights learned from these recent TCR–pMHC-I structures and their impact on T cell activation.     

Integration and characterization of gas cluster processing for copper interconnects electromigration improvement

Basic physical properties as well as electrical and reliability performance of Infusion™ processing were evaluated. This approach, proposed as an alternative to CuSiN and electrolessly deposited Co-alloys, was shown to join the benefits of these two techniques without well-known associated drawbacks. Indeed, it is a uniform process, acting as an efficient Cu diffusion barrier, which does not require specific integration development. Different processes were introduced in a multi-level interconnect stack using ULK/USG stack as IMD, showing excellent electrical properties, and three times electromigration time-to-failure improvement with respect to standard SiCN barrier. However, it was shown that existing process conditions lead to some introduction of N atoms into ULK dielectric, showing there is still some room for process optimization in architectures using un-capped ULKs, to keep the benefits of EM improvement and aggressive effective dielectric constant.     

Preparation of salt-free protein products from acid or alkali-treated proteins

Wheat gluten has been hydrolysed in either alkali or acid to give a soluble protein product. Instead of using an inorganic acid or base to neutralize the hydrolysates, acidic or basic proteins have been used to neutralize the reaction mixtures after alkali or acid treatment, respectively. Both casein and a deamidated wheat gluten have been investigated as suitable acidic proteins. Salmine has been used as the basic protein for neutralization. This technique has the advantages of avoiding inorganic salt formation in the product and improving the amino acid composition of the final product. In particular, casein has been studied in some detail for its utility in neutralizing the reaction mixtures of alkali-treated proteins, mainly because it is readily available on an industrial scale and already has many applications in the food industry. Only the sulphur-containing essential amino acids are deficient in the products formed when alkali-treated gluten is neutralized with casein. The other essential amino acids are in excess of the recommended dietary intake.     

Influence of surface-coatings on titanium-alloy resistance to fretting fatigue in cryogenic environment

Fretting damage, also known as small amplitude oscillatory sliding motion, can lead to catastrophic failure in many industrial applications. The understanding of fretting fatigue and its reproduction in laboratory tests have enable us to evaluate the fretting resistance of homogeneous substrate. To reduce the damage caused by fretting fatigue increasing use has been made of coatings or heat treatments which result in non homogeneous solids. From a theoretical point of view, ascertaining the mechanical behaviour of materials so modified is quite complex due to insufficient definition of the contact parameters. This present study seeks to analyse a layered medium undergoing fretting fatigue and the improvement of its fatigue criterion.     

Monitoring damage by acoustic emission in bearing steels in cryogenic environment

Fatigue is the usual type of damage occurring at heavily loaded hertzian contact zones such as those found on bearings. An in-depth knowledge of the origins and evolution of fatigue-induced damage is crucial for correctly foreseeing the life span of mechanical parts.In order to monitor crack-initiation during an extremely low-temperature (cryogenic) fatigue test, acoustic emission measurements were used.In this present study we show that the analysis of those signals emitted during testing is a reliable means of distinguishing and quantifying the first two stages of fatigue-induced damage, namely microscopic crack-initiation and crack-growth. The after-the-fact analysis of failed test specimens (their autopsy, so to speak) provides us with a detailed picture of these stages by revealing the crack-initiation zones and the way in which they grow.     

Expression and activity of a recombinant chimeric protein composed of pokeweed antiviral protein and of human interleukin-2

Liv.100 is an improvised herbal formulation of Liv.52. Liv.52 is an important component of the ayurvedic system of medicine. This report highlights on the protective effect of Liv.52 and Liv.100 against in vitro peroxidation induced by hydrogen peroxide in rat liver homogenate. Addition of the two herbal formulations reduced the peroxidation effect of hydrogen peroxide in the dose- and time-dependent manner. The protective effect of the drugs is attributed to the enhanced supply of reduced glutathione that inhibit the deleterious process of lipid peroxidation. The results suggest on the antioxidant potential of Liv.52 and Liv.100.     

Reliability of an automatic sensing test with beat-to-beat display of the signal amplitude

In contrast to testing of the capture threshold, the reliability of sensing tests has been little studied. This study was performed to test the automatic sensing algorithm included in the Biotronik pacing systems. The automatic measurements made by the devices were compared with the direct manual measurements made of 271 atrial (72%) or ventricular (28%) electrograms recorded in ten patients. A high correlation (r = 0.995, P < 0.0001) was found between the two types of measurements. The use of this function should facilitate the verification of accurate sensing during the long-term follow-up of pacemaker patients, and offers a tool to analyze the variations in amplitude of intracardiac signals.