Electromechanical Surfacing Technique

The paper considers an electromechanical surfacing technique of parts’ work surfaces. It was found out that depending on strain temperature, rate and degree there were special type structures formed on a surface layer with a phase change (a bright layer), i.e. a hot deformed structure with and without recrystallization and a cold deformed structure. Depending on the original structure and hardening conditions, during surfacing of parts a thickness of this area may achieve 0.3 mm max. Impact of steel electromechanical treatment on the structure and the surface layer was found out. Depending on properties of surfaces being treated it is possible to use plate-like and roller-type tools for electromechanical hardening. It was shown that roller- type tools possessed enhanced durability and enlarged areas of surfaces being treated, though ensured poorer finish of surfaces being treated.

Kinetic Study of the Atmospheric Oxidation of a Series of Epoxy Compounds by OH Radicals

The kinetics of the gas-phase reactions of hydroxyl radicals with cyclohexene oxide (CHO), 1,2-epoxyhexane (EHX), 1,2-epoxybutane (12EB), trans-2,3-epoxybutane (tEB) and cis-2,3-epoxybutane (cEB) have been investigated using the relative rate technique. The experiments have been performed at (298 ± 3) K and (760 ± 10) Torr total pressure of synthetic air using different reference compounds in a 1080 l Quartz Reactor (QUAREC) and a 480 l Duran glass chamber. The following room temperature rate coefficients (cm3 molecule−1 s−1) were obtained: k1 (OH+CHO) = (5.93 ± 1.78) × 10−12, k2 (OH+EHX) = (5.77 ± 1.29) × 10−12, k3 (OH+12EB) = (1.98 ± 0.39) × 10−12, k4 (OH+cEB) = (1.50 ± 0.26) × 10−12, k5 (OH+tEB) = (1.81 ± 0.42) × 10−12. With the exception of previous studies for 1,2-epoxybutane and cyclohexene oxide, this is to the best of our knowledge the first kinetic study of the reaction of these compounds with OH radicals. Atmospheric lifetimes, reactivity trends and atmospheric implications are discussed considering the epoxy compound rate coefficients obtained in the present study. In addition to a direct comparison with the literature data where possible, the results from the present study are compared with values estimated from the Structure Activity Relationship method.

Recent Studies on the Fabrication of Multilayer Films by Magnetron Sputtering and Their Irradiation Behaviors

Multilayer films with high-density layer interfaces have been studied widely because of the unique mechanical and functional properties. Magnetron sputtering is widely chosen to fabricate multilayer films because of the convenience in controlling the microstructure. Essentially, the properties of multilayer films are decided by the microstructure, which could be adjusted by manipulating the deposition parameters, such as deposition temperature, rate, bias, and target–substrate distance, during the sputter process. In this review, the influences of the deposition parameters on the microstructure evolution of the multilayer films have been summarized. Additionally, the impacts of individual layer thickness on the microstructure evolution as well as the irradiation behavior of various multilayer films have been discussed.

Analysis of Cryopreservation Protocols and Their Harmful Effects on the Endothelial Integrity of Human Corneas

Corneal cryopreservation can partially solve the worldwide concern regarding donor cornea shortage for keratoplasties. In this study, human corneas were cryopreserved using two standard cryopreservation protocols that are employed in the Tissue Bank of the Teresa Herrera Hospital (Spain) to store corneas for tectonic keratoplasties (TK protocol) and aortic valves (AV protocol), and two vitrification protocols, VS55 and DP6. Endothelial viability and general corneal state were evaluated to determine the protocol that provides the best results. The potential corneal cryopreservation protocol was studied in detail taking into consideration some cryopreservation-related variables and the endothelial integrity and stroma arrangement of the resulting cryopreserved corneas. TK corneas showed mostly viable endothelial cells, while the others showed few (AV) or none (DP6 and VS55). The corneal structure was well maintained in TK and AV corneas. TK corneas showed endothelial acellular areas surrounded by injured cells and a normal-like stromal fiber arrangement. Cryoprotectant solutions of the TK protocol presented an increasing osmolality and a physiological pH value. Cooling temperature rate of TK protocol was of 1 °C/min to −40 °C and 3 °C/min to −120 °C, and almost all of dimethyl sulfoxide left the tissue after washing. Future studies should be done changing cryopreservation-related variables of the TK protocol to store corneas of optical grade.

Research on Modeling Crystallographic Texture Evolution of Al Alloy 7075

Crystallographic texture is related to the anisotropy or isotropy of material physical properties, including mechanical performance. The crystallographic effect in micromachining is more significant than that in macro-processing owing to that the depth of the cut and the grain size are in the same order. It is of great significance to model the crystallographic texture evolution induced by mechanical and thermal load during micro-machining to investigate the surface integrity and performance of the finished product. This study performed hot deformation experiments of Al alloy 7075 (AA7075) under various input parameters, including the temperature, temperature rate, stain rate, and strain, which was designed using the Taguchi method. Following that, crystallographic orientation of the samples before and after the deformation was tested using electron back-scattered diffraction (EBSD). Then, the crystallographic texture evolution was modeled with the parameters obtained by fitting a part of the experimental data. The crystallographic texture evolution of AA7075 under different levels of input parameters is studied and analyzed. Finally, the sensitivity of crystallographic orientation evolution to the process parameter is analyzed. The results indicate that these four input parameters have a significant impact on some crystallographic texture of the specimens. The proposed model is instructive in the future investigation of micromachining and microstructure evolution.

A Novel Approach to Estimate the Air Temperature Through the Air Pollution and Meteorological Conditions in Biskra Under the Parameters Astronomical, and Atmospheric

Propose of the experimental study a found a sufficient model to predict the ambient temperature over the area of Biskra, Algeria, taking into account new air pollution factors such as CO, CO2, O3, and NO2. We found that the effect of air pollution, astronomical and meteorological elements have obvious in the ambient temperature, and be behavior, according to regional characteristics. Using the fitting of the experimental data for establishing a set of prediction data sets of pollutants, astronomical, and meteorological elements at the University of Biskra, Algeria. We recorded the highest NO2 value in March at an estimated value of 1.6.1015 (mole/cm), where the ambient temperature rate is low. The mathematical model obtained gives a satisfactory results, because they were substantially identical and without almost any error with the experimental data. Finally, the latter can be used by engineers and especially those who work in the environmental field which is very sensitive to temperature variation and it can influence the health of the human being.