Correlation Between Cutting Data Selection and Chip Form in Stainless Steel Turning

This article presents investigations related to the turning of stainless steel as a representative of difficult-to-cut materials and the effectiveness of selected chip breakers working in the local machining environment. Martensitic steel AISI 416 was used to test two commercially available types of chip breaker. The efficiency of a chip breaker working in the range of cutting conditions recommended (by the tool manufacturers) was the aim of the turning tests. As a result of the investigations an algorithm of cutting condition selection, combining both the cutting tests and the simulation procedure for the efficiency of the chip breaker was created. The vision system, equipped with a high-speed camera was used for chip form estimation. Simultaneously, the cutting force components were measured to check if the simulation calculation was correct. The FEM simulation was applied to estimate the manner in which the chip groove was filled. The article presents certain recommendations for cutting condition correction in the local machining environment for the purpose of achieving an acceptable chip form.     

Analysis of the intake of sodium with cereal products by the population of Poland

The study aimed to analyse the intake of Na with cereal products by the population of Poland. In addition, based on available literature, changes in the content of Na in bread sold in the Polish market from 2009 to 2018 were analysed with regard to Na intake reduction campaigns held in Poland since 2009 popularising information about the adverse effect of sodium on the human cardiovascular system. The results led to the conclusion that the analysed products contained 3.042 ± 3.4 g of Na per 1 kg of fresh product. The content of Na in the analysed products was bread > bread rolls > grains > pasta > rice. Cereal products provide 48.3 % of an adult’s intake of Na, where as much as 48.2 % is covered by bread, with only 0.04 % by grains, 0.04 % by pasta, and 0.01 % by rice. According to information available in reference literature from 2009–2017 the content of Na in baked goods has not been subject to significant modifications. In Poland, with regard to an excessive consumption of Na, efficient strategies must be developed to increase the awareness of consumers and to reduce the use of table salt in the most popular products, and in particular in baked goods. One of the ways to reduce the intake of Na would be consumers’ selection of an adequate range of foodstuffs naturally poor in this element or having its content reduced by means of a suitable technology. This can be a significant component of practices preventing the development of hypertension. However, the fact that information about the content of Na in cereal products is often missing from product labels makes consumer choice difficult.     

The Particle Image Velocimetry Experimental Study of Flame Extinction in Standard Square Flammability Column Resulting From Stretching

The main goal of this work is to determine experimentally local stretching rate distribution along the limits of methane/air and propane/air flames, using particle image velocimetry (PIV). This method allows obtaining necessary moving flame velocity fields in a standard flammability column and also recognition of the flame structures. For this purpose each mixture was seeded with MgO particles (of known size) before entering the tube (column), using a special system. The amount of seeds in the mixture, their dispersion system, and the laser power producing a sheet of light penetrating the column were carefully chosen (so as not to disrupt the combustion or flame propagation in it). After a learning process, this finally it allowed us obtain good-quality velocity field images in the region of concern, images acceptable for further processing. The methodology developed for these experiments proved to be reliable and able to supply analyses with repeatable data. On the basis of performed experiments it was possible to derive the flame stretching rate that causes its extinction in both mixtures.     

Bending-Torsion Response of Rib-Reinforced Cantilever Plates

The objective of this paper is to present the feasibility of applying Vlasov's theory of thin walled bars to model the behavior of rib-reinforced cantilevered plates. A simple analytical model based on Vlasov's theory is presented and validated against experimental results. It is shown that the presented theoretical method is simple and sufficiently accurate to be used as a design tool. The presented approach is also valid for plates fabricated from composite materials.     

When cognitive exertion does not yield cognitive gain: Toward an informational explanation of learned helplessness.

This study tested a new information-processing explanation of learned helplessness that proposes that an uncontrollable situation produces helplessness symptoms because it is a source of inconsistent, self-contradictory task information during problem-solving attempts. The flow of such information makes hypothesis-testing activity futile. Prolonged and inefficient activity of this kind leads in turn to the emergence of a state of cognitive exhaustion, with accompanying performance deficits. In 3 experiments, Ss underwent informational helplessness training (IHT): They were sequentially exposed to inconsistent task information during discrimination problems. As predicted, IHT was associated with subjective symptoms of irreducible uncertainty and resulted in (a) performance deterioration on subsequent avoidance learning, (b) heightened negative mood, and (c) subjective symptoms of cognitive exhaustion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Scandium(III) Triflate‐Catalyzed anti‐Markovnikov Hydrothiolation of Functionalized Olefins

Scandium(III) triflate promoted highly selective addition of thiols to functionalized olefins under mild conditions. The addition follows anti‐Markovnikov regioselectivities, which are unusual for Lewis acids‐catalyzed hydrothiolation. This reaction marks broad functional groups tolerance, which opens a beneficial synthetic route to functionalized and biologically active thio‐compounds. This method is broadly applicable and offers a simple work‐up in the green manner.

     

Charge transfer and partial pinning at the contacts as the origin of a double dip in the transfer characteristics of graphene-based field-effect transistors

We discuss the origin of an additional dip other than the charge neutrality point observed in the transfer characteristics of graphene-based field-effect transistors with a Si/SiO2 substrate used as the back-gate. The double dip is proved to arise from charge transfer between the graphene and the metal electrodes, while charge storage at the graphene/SiO2 interface can make it more evident. Considering a different Fermi energy from the neutrality point along the channel and partial charge pinning at the contacts, we propose a model which explains all the features observed in the gate voltage loops. We finally show that the double dip enhanced hysteresis in the transfer characteristics can be exploited to realize graphene-based memory devices.