Machinability investigation of polymer/GNP nanocomposites in micro-milling

Nanoparticles such as graphene have been added to various polymer matrices to enhance the mechanical, thermal, and electrical properties of polymer materials that require complex designs on a microscopic scale. Micro-machining is used to process these nanocomposite materials to achieve high surface quality and dimensional accuracy while maintaining high productivity. In this study, a systematic micro-milling experiment was performed on polymer/graphene nanoplatelet (GNP) nanocomposites to advance knowledge of the micro-machinability of these materials. It evaluates the effect of the addition of 0.1wt% GNP nanoparticles on machined surface morphology, chip formation, cutting forces, and tool wear. It is found that the addition of GNP nanoparticles changes the slot edge formation mode from burring mode to chipping mode.

Milky Way–like Gas Excitation in an Ultrabright Submillimeter Galaxy at z = 1.6

Based on observations with the IRAM 30 m and Yebes 40 m telescopes, we report evidence of the detection of Milky Way–like, low-excitation molecular gas, up to the transition CO(J = 5–4), in a distant, dusty star-forming galaxy at z CO = 1.60454. WISE J122651.0+214958.8 (alias SDSS J1226, the Cosmic Seahorse), is strongly lensed by a foreground galaxy cluster at z = 0.44 with a source magnification of μ = 9.5 ± 0.7. This galaxy was selected by cross-correlating near-to-mid-infrared colors within the full-sky AllWISE survey, originally aiming to discover rare analogs of the archetypical strongly lensed submillimeter galaxy SMM J2135–0102, the Cosmic Eyelash. We derive an apparent (i.e., not corrected for lensing magnification) rest-frame 8–1000 μm infrared luminosity of μ L IR = 1.66 − 0.04 + 0.04 × 10 13 L ⊙ and apparent star formation rate μSFRIR = 2960 ± 70 M ⊙ yr−1. SDSS J1226 is ultrabright at S 350μm ≃ 170 mJy and shows similarly bright low-J CO line intensities as SMM J2135–0102, however, with exceptionally small CO(J = 5–4) intensity. We consider different scenarios to reconcile our observations with typical findings of high-z starbursts, and speculate about the presence of a previously unseen star formation mechanism in cosmic noon submillimeter galaxies. In conclusion, the remarkable low line luminosity ratio r 5,2 = 0.11 ± 0.02 is best explained by an extended, main-sequence star formation mode—representing a missing link between starbursts to low-luminosity systems during the epoch of peak star formation history.

Cold Molecular Gas in Merger Remnants. II. The Properties of Dense Molecular Gas

We present the 3 mm wavelength spectra of 28 local galaxy merger remnants obtained with the Large Millimeter Telescope. Sixteen molecular lines from 14 different molecular species and isotopologues were identified, and 21 out of 28 sources were detected in one or more molecular lines. On average, the line ratios of the dense gas tracers, such as HCN (1–0) and HCO+(1–0), to 13CO (1–0) are 3–4 times higher in ultra/luminous infrared galaxies (U/LIRGs) than in non-LIRGs in our sample. These high line ratios could be explained by the deficiency of 13CO and high dense gas fractions suggested by high HCN (1–0)/12CO (1–0) ratios. We calculate the IR-to-HCN (1–0) luminosity ratio as a proxy of the dense gas star formation efficiency. There is no correlation between the IR/HCN ratio and the IR luminosity, while the IR/HCN ratio varies from source to source ((1.1–6.5) × 103 L ☉/(K km s−1 pc2)). Compared with the control sample, we find that the average IR/HCN ratio of the merger remnants is higher by a factor of 2–3 than those of the early/mid-stage mergers and nonmerging LIRGs, and it is comparable to that of the late-stage mergers. The IR-to-12CO (1–0) ratios show a similar trend to the IR/HCN ratios. These results suggest that star formation efficiency is enhanced by the merging process and maintained at high levels even after the final coalescence. The dynamical interactions and mergers could change the star formation mode and continue to impact the star formation properties of the gas in the postmerger phase.

Teaming up in entrepreneurship education: does the team formation mode matter?

PurposeThis paper investigates the importance of team formation in entrepreneurship education, and the authors ask: how do different team formation strategies influence teamwork in higher education experiential learning-based entrepreneurship courses?Design/methodology/approachEmploying a multiple case study design, the authors examine 38 student teams from three different entrepreneurship courses with different team formation paths to uncover potential links between team formation and learning outcomes.FindingsThe authors find that team formation mode matters. Randomly assigned teams, while diverse, struggle with handling uncertainty and feedback from potential stakeholders. In contrast, student self-selected teams are less diverse but more robust in handling this pressure. Results suggest that in randomly assigned teams, the entrepreneurial project becomes the team's sole reference point for well-being. Seeking to protect the project, the team's ability to deal with uncertainty and external feedback is limited, stifling development. In student self-select teams, team well-being becomes a discrete reference point. This enables these teams to respond effectively to external project feedback while nurturing team well-being independently.Originality/valueEducation theories' implications about the benefit of team diversity may not apply to experiential learning-based entrepreneurship education's typical level of ambiguity and uncertainty. Therefore, educators may have to reconsider the unique dynamics of team formation strategies to ensure strong teamwork and teamwork outcomes.

Effect of Pr6O11 on the Microstructures and Mechanical Properties of High-Strength Steel Weld Metal

The effect of Pr6O11 on the microstructure and mechanical properties of high-strength steel weld metal was investigated by optical microscopy, scanning electron microscopy and mechanical testing. Three different contents of Pr6O11 were added to the flux-cored wires. The results demonstrate that the addition of 1% Pr6O11 can promote the refinement and spheroidization of inclusions, refine the grains, form acicular ferrites in the weld metal, and significantly improve the toughness. The addition of Pr6O11 promoted the formation of rare earth composite inclusions and acicular ferrites in the weld metal, refined the lath microstructure, inhibited the formation of martensite and bainite. The crack formation mode changed from the boundary cracking of the bainite clusters caused by the surface shear stress to the surface shear stress-induced decohesion of inclusion. Excessive addition of Pr6O11 will reduce the number of inclusion nucleation and deteriorate the mechanical properties. The wire No.2 with 1% Pr6O11 had the good comprehensive mechanical properties.

The role of collision speed, cloud density, and turbulence in the formation of young massive clusters via cloud–cloud collisions

ABSTRACT Young massive clusters (YMCs) are recently formed astronomical objects with unusually high star formation rates. We propose the collision of giant molecular clouds (GMCs) as a likely formation mechanism of YMCs, consistent with the YMC conveyor-belt formation mode concluded by other authors. We conducted smoothed particle hydrodynamical simulations of cloud–cloud collisions and explored the effect of the clouds’ collision speed, initial cloud density, and the level of cloud turbulence on the global star formation rate and the properties of the clusters formed from the collision. We show that greater collision speed, greater initial cloud density and lower turbulence increase the overall star formation rate and produce clusters with greater cluster mass. In general, collisions with relative velocity ≳ 25 km s−1, initial cloud density ≳ 250 cm−3, and turbulence of ≈2.5 km s−1 can produce massive clusters with properties resembling the observed Milky Way YMCs.

Kołowy Model Sposobów Kształtowania się Tożsamości: założenia teoretyczne i empiryczna weryfikacja

Circumplex of Identity Formation Modes: Theoretical Assumptions and Empirical Verification The article presents theoretical assumptions and summarizes the results of research on the Circumplex of Identity Formation Modes. The model was created as an attempt to synthesize knowledge on identity formation gathered in the stream of research initiated by James E. Marcia (1966), based on the Erik H. Erikson’s (1959) theory of psychosocial development. In the model: (1) the key concept is the identity formation mode, (2) traditional categories of exploration and commitment have been redefined and used as basic axes to distinguish eight identity formation modes, between which relationships are precisely defined in accordance with the rules of the circumplex model, (3) due to redefinition of exploration and commitment, the model can be used in research on personal identity in various developmental periods, and (4) the place of identity variables in the personality structure has been precisely defined. Circumplex of Identity Formation Modes was introduced to international literature and research on its verification and usefulness was conducted (Cieciuch, Topolewska, 2017; Topolewska, Cieciuch, 2017; Topolewska-Siedzik, Cieciuch, 2018, 2019; Topolewska-Siedzik, Cieciuch, Strus, 2019).

The Tamunier gold deposit in the Northern Ural: Physicochemical formative conditions, ore and fluid sources, genesis

Research subject.This research study was aimed at investigating metasomatic minerals and ores in the Tamunier Deposit, which is located in the Northern Urals, at the Eastern side of the Tagil megazone within the Auerbach volcano-plutonic belt.Materials and methods.Well core samples were investigated using a complex of research methods, including optical and electron microscopy, X-ray spectral microanalysis, mineral geothermometry, thermobarogeochemistry (microthermometry, gas chromatography, determination of the salt composition of fluid inclusions in minerals) and isotope geochemistry (isotopes C, O, S, Sr, Pb).Results.A genetic model describing the formation of the Tamunier deposit was developed using the data obtained on its geological structure, mineral composition of metasomatites and ores, fluid formation mode, sources of ore matter and ore-bearing fluid. In the proposed model, the magmatogenic sodium chloride fluid carrying ore components and S is separated from the Auerbach complex at the depth of intrusion. Penetrating to the surface, this fluid interacts with the rocks of volcanic-sedimentary strata, thereby extracting a number of components, including CO2, S and Sr.Conclusion.Despite the presence of sulphide mineralization of hydrothermal-sedimentary genesis in the volcanogenic-sedimentary rock mass, the data obtained has allowed us to refer the gold-sulphide ores under study to magmatogenic-hydrothermal formations. The estimated P-T conditions (t= 100–370ºС andP= 0.4–0.6 kbar) and the shallow depth of the Tamunier field have shown its correspondence to the sub-epithermal level in the model of the porphyry-epithermal ore-magmatic system.