Influence of manufacturing errors on the dynamic behavior of planetary gears

Planetary gears are widely used in the transmissions of helicopters, automobiles, aircraft engines, etc. They have substantial advantages such as compactness and a large torque-to-weight ratio. In this work, a plane model of a planetary gear was investigated. The energetic Lagrange formulation was used to recover the equations of motion of the system. A modal analysis was performed, and the influence of gyroscopic effect in particular was scrutinized. The dynamic response was computed by an iterative spectral method. The excitation is induced by time-varying the gearmesh stiffness. The cases of a healthy planetary gear and one with the presence of eccentricity and profile error were compared. The influence on the transmission ratio was also studied.     

Synthesis,surface profile,nonlinear reflective index and photophysical properties of curcumin compound

Curcumin and other three curcuminoids (bisdemethoxycurcumin, α-chlorocurcumin and α-methylcurcumin) were synthesized. Fourier transform infrared spectroscopy, Fluorescence quantum yields, AFM analysis and image surface profiles were characterized. All compounds possessed electron donor moieties at both ends of the conjugated π-system and an electron acceptor moiety in the middle of the molecules (D-A-D system) and should exhibit different optical properties depending on substituents on the benzene rings. The third order nonlinear optical properties of the curcuminoids have been investigated by z-scan technique. The optical response was characterized by measuring the refractive index (n₂) of the derivatives of curcumin using the Z-scan technique. The compounds showed negative and large nonlinear refractive index values of the order of 10^?7 cm²/W and reverse saturable absorption with high values of the nonlinear absorption coefficient of the order of 10^?4 cm/W. The nonlinear refractive index was found to vary with the different compound. The optical constants of the different compound films were studied and the dispersion of the refractive index was discussed in terms of the Wemple-DiDomenico single oscillator model. The photo-physical properties of these compounds are compared to those of native curcumin, in order to provide a rationale to the design of samples with molecular structures optimized for a photosensitizer. These types of materials may be considering new photonic applications.     

Thermal,Microstructural, Magnetic,and Optical Studies for La0.7M0.3CoO3 (M = Ca,Pb) Cobaltites for Potential Magneto-optical Applications

Journal of Superconductivity and Novel Magnetism - In this work, the thermal, microstructural, magnetic, and optical studies for both La0.7Ca0.3CoO3 (LCCO) and La0.7Pb0.3CoO3 (LPCO) cobaltite...     

Structural,dielectric and electrical properties of Sol–gel auto-combustion technic of CuFeCr0.5Ni0.5O4 ferrite

Journal of Materials Science - The CuFeCr0.5Ni0.5O4 (CFO) compound was synthesized using sol–gel reaction combustion technic. The structural analysis showed that the obtained composites have...     

Decision‐tree‐based methods for differential diagnosis of β‐thalassemia trait from iron deficiency anemia

Several discrimination indices have been proposed to distinct between β‐thalassemia trait (βTT) and iron deficiency anemia (IDA). This study is the first application of tree‐based methods for differential diagnosis of βTT from IDA. One hundred forty‐four patients with hypochromic microcytic anemia aged 18–40 years old from Ayat Hospital of Tehran were recruited. Classification and Regression tree, CHi‐squared Automatic Interaction Detector (CHAID), Exhaustive CHi‐squared Automatic Interaction Detector (E‐CHAID), Quick, Unbiased, Efficient Statistical Tree (QUEST), Classification Rule with Unbiased Interaction Selection and Estimation (CRUISE), and Generalized, Unbiased, Interaction Detection and Estimation (GUIDE) have been used to discriminate the diagnosis. Mean corpuscular volume (MCV) was found as the main predictor in discrimination. All the mentioned tree‐based methods showed acceptable sensitivity, specificity, accuracy, Youden's index, false positive and negative rate, positive and negative predictive values and AUC in differential diagnosis of βTT from IDA. However, Classification Rule with Unbiased Interaction Selection and Estimation revealed more precise classification with an area under the curve value of 0.99. Decision‐tree‐based methods can be used to develop sensitive and accurate diagnostic methods for differentiating βTT from IDA.     

Autophagy,Unfolded Protein Response,and Neuropilin-1 Cross-Talk in SARS-CoV-2 Infection: What Can Be Learned from Other Coronaviruses

The COVID-19 pandemic is caused by the 2019–nCoV/SARS-CoV-2 virus. This severe acute respiratory syndrome is currently a global health emergency and needs much effort to generate an urgent practical treatment to reduce COVID-19 complications and mortality in humans. Viral infection activates various cellular responses in infected cells, including cellular stress responses such as unfolded protein response (UPR) and autophagy, following the inhibition of mTOR. Both UPR and autophagy mechanisms are involved in cellular and tissue homeostasis, apoptosis, innate immunity modulation, and clearance of pathogens such as viral particles. However, during an evolutionary arms race, viruses gain the ability to subvert autophagy and UPR for their benefit. SARS-CoV-2 can enter host cells through binding to cell surface receptors, including angiotensin-converting enzyme 2 (ACE2) and neuropilin-1 (NRP1). ACE2 blockage increases autophagy through mTOR inhibition, leading to gastrointestinal complications during SARS-CoV-2 virus infection. NRP1 is also regulated by the mTOR pathway. An increased NRP1 can enhance the susceptibility of immune system dendritic cells (DCs) to SARS-CoV-2 and induce cytokine storm, which is related to high COVID-19 mortality. Therefore, signaling pathways such as mTOR, UPR, and autophagy may be potential therapeutic targets for COVID-19. Hence, extensive investigations are required to confirm these potentials. Since there is currently no specific treatment for COVID-19 infection, we sought to review and discuss the important roles of autophagy, UPR, and mTOR mechanisms in the regulation of cellular responses to coronavirus infection to help identify new antiviral modalities against SARS-CoV-2 virus.     

Fatty acid composition of green crab (Carcinus mediterraneus) from the Tunisian mediterranean coasts

Green crab (Carcinus mediterraneus) was analysed for proximate and fatty acid composition. The yields of crab claw meat and hepatopancreas were 24.9–26.1% and 8.8–9.2%, respectively. Crude protein (NX6.25) and crude fat contents of crab claw meat were 17.8–18.2% and 0.85–1%, respectively, on a dry weight basis, while those of hepatopancreas were 13–14% and 21.8–22.7%, respectively. The fatty acid (FA) profiles were significantly different between claw meat, and hepatopancreas of the crab. The percentage of total saturated fatty acids was higher in the hepatopancreas (25.15–26.24% of total FAs) than in the claw meat (22.58–23.49% of total FAs). The main saturated fatty acids were palmitic acid (16:0) and stearic acid (18:0). Palmitic acid represented 11.5–12.45% and 11–11.5% of the total FAs in the hepatopancreas and in the claw meat, respectively. The percentages of stearic acid were 7.8–8.3% and 7–7.3% in the hepatopancreas and in the claw meat, respectively. Meanwhile, oleic acid (18:1) was the dominant monounsaturated fatty acid which represents 16.15–16.85% and 15.4–15.7% of the hepatopancreas and the claw meat total FAs, respectively. The dominant PUFA was arachidonic acid (20:4n-6) in both claw meat and hepatopancreas. The content of arachidonic acid (20:4n-6) was higher in the hepatopancreas (13–13.5%) than in the claw meat (10.5–11.8%).     

Evaluating the effects of the magnitude and amplification of pseudo-static acceleration on reinforced soil slopes and walls using the limit equilibrium Horizontal Slices Method

The effects of horizontal and vertical pseudo-static forces on reinforced soil structures are investigated in the paper. In particular, the effects of the magnitude and amplification of the ground acceleration on the seismic stability of reinforced soil slopes and walls have been investigated using the Horizontal Slices Method (HSM). The HSM is a limit equilibrium method for the analysis of reinforced soil structures, which offers a number of benefits over conventional vertical slice methods. First, a parametric study using acceptable geotechnical, geometrical and design parameters was undertaken. The results of the parametric analysis are presented in dimensionless form relating to the force required to maintain stability of the slope (K) and the required length of the reinforcements (L_c/H). Different rotational and planar slip surfaces are shown for various slopes and walls with different geotechnical strength parameters. Second, the capability of the HSM to consider the effect of earthquake amplification on the stability analysis of reinforced soil structures was considered. It has been shown that the effect of horizontal seismic acceleration on the response of reinforced slopes and walls depends mainly on the geotechnical strength parameters. The effect of vertical seismic acceleration on the performance of reinforced slopes is not significant for low values of horizontal seismic acceleration. It has been concluded that ignoring the effect of the amplification phenomenon could result in an underestimated design.     

Experimental study on seismic deformation modes of reinforced-soil walls

A series of 1-g shaking table tests were conducted on 1 m high reinforced-soil wall models. The physical models were subjected to harmonic sinusoidal-like time history input motions at frequencies of 2, 5, 8 and 10 Hz. The effects of parameters such as soil density, reinforcement length, spacing and stiffness on the seismic response of the model walls were studied. Free-sliding toe boundary and wrap-around wall facing were selected to reveal all potential deformation modes of the wall and different deformation shapes of the facing. Different deformation modes (overturning and bulging) of the facing as well as base sliding were observed. Determinant parameters in the formation of each mode were identified by introducing internal failure indexes. A bulging index was introduced to measure the bulging intensity of the wall facing. Additionally, the distribution of the shear stiffness modulus (G) and damping ratio (D) of the reinforced soil along the wall height were assessed. The effect of the confining pressure (σ_v) and shear strain on variations of G and D were traced. G proved to be dependent on σ_v and, as expected, to be incremental with depth below the crest of the wall. Based on measurements and relevant approximations, no incremental or decremental patterns for D were detected along the wall height. Moreover, at large strains of about 10⁻³, an average D of about 20% was observed. Overall, based on the results of physical model testing in this study, which confirm similar findings of previous research, it was concluded that reinforcement stiffness is a key parameter dominating the seismic response and deformation mode of a wall and not reinforcement ultimate tensile strength, which is currently used as the main parameter for wall design in existing codes.