Temperature effect on mechanical and tribological properties of WNiCoFe alloy powder for cutting tools

In order to improve the wear resistance of WNiCoFe alloy for cutting tools, WNiCoFe alloy powder is prepared by multiple metals electrolysis, alloy powder and its sintered morphology is observed and phase is analyzed using X-ray diffractometer and scanning electron microscope (SEM), the effect of sintering temperature on its physical mechanics and friction properties was studied. The results show that the prepared WNiCoFe alloy powder is alloyed to some extent, irregular and finer particle size, the diffraction peaks of Co3Fe7 and Fe19Ni are formed in addition to the elemental Fe; the maximum hardness of the sintered is 107.6HRB, the maximum bending strength at three points is 1638.3 mpa, the maximum density is 96.2%, and wear loss is 0.498–0.555 g when WNiCoFe alloy powder is sintered at 800∘C. Diamond tools are made with WNiCoFe alloy powder as the main matrix composition, and cut hard stone, cutting velocity is 8.6 m2/h and life is 11.3 m2/m, which has a good comprehensive performance.

Are Sansevieria trifasciata better for airborne particulate matter removal dead or alive?

Particulate matter (PM) is a common air pollutant linked to many human deaths and illnesses worldwide. Once emitted in the air, PM is most effectively removed by plants in phytoremediation. While the physical mechanics and factors of phytoremediation have been well-studied, there has been little attention regarding its biological mechanisms. In this empirical study, we measure the net effect of biological processes in Sansevieria trifasciata on its ability to remove PM from an enclosed space by comparing the time taken for PM to decrease in enclosures containing living specimens versus dried and pressed specimens. Our results show that live specimens are in fact worse at removing PM from their enclosures as compared to dried and pressed specimens. This suggests that biological processes can be detrimental to PM removal for some plants species.

In Ancient Rome

The history of reading in antiquity is wholly dependent on literary sources that must be read with care; one misinterpreted passage can enable an entire misguided history. This is the case with Augustine’s account of Ambrose reading silently, and the tenacious misapprehension that such reading was impossible in antiquity. Another reading of the passage points not to reading’s physical mechanics but to its psychological unknowability, and the distance that reading creates between subjects whether in the same room or at a historical distance. This should prompt us to consider other unknowable or invisible aspects of ancient Roman reading, like its dependence on enslaved labor, ubiquitous but almost never described. The unknowability of ancient reading invites us to consider its cultural idiosyncrasy; that idiosyncrasy, in turn, provides exciting new points of contact with our current age of digital reading.

About mathematical simulation of processes for high-speed loading of materials on Department of Physical Mechanics of St. Petersburg State University

The researches of shock-wave processes in the constructional materials are actual, but carrying out of natural experiments is extremely inconvenient and expensive, and sometimes it is even impossible to replicate. Therefore basically all researches of these problems are reduced to various cases of simulation of processes for high-speed loading of materials in the laboratory circumstances. In the paper we consider following directions of mathematical simulation of processes for high-speed loading of materials that were made on department of physical mechanics of St. Petersburg State University: the simulation of shock-loaded media by using of dynamics of dislocations; the simulation of high-speed loading of media with the account of the relaxation phenomena in a near-surface region; the simulation of propagation of the short elastoplastic impulse in medium under the condition of influence of a weak magnetic field; the generation of mathematical models of deformation and destruction of thin metal rings by a magnetic-pulse method; the simulation of crack propagation during the short-term pulse loading.