Modal Analysis of Conceptual Microsatellite Design Employing Perforated Structural Components for Mass Reduction

Mass reduction is a primary design goal pursued in satellite structural design, since the launch cost is proportional to their total mass. The most common mass reduction method currently employed is to introduce honeycomb structures, with space qualified composite materials as facing materials, into the structural design, especially for satellites with larger masses. However, efficient implementation of these materials requires significant expertise in their design, analysis, and fabrication processes; moreover, the material procurement costs are high, therefore increasing the overall program costs. Thus, the current work proposes a low-cost alternative approach through the design and implementation of geometrically-shaped, parametrically-defined metal perforation patterns, fabricated by standard processes. These patterns included four geometric shapes (diamonds, hexagons, squares, and triangles) implemented onto several components of a structural design for a conceptual satellite, with a parametric design space defined by two scale factors and also two aspect ratio variations. The change in the structure’s fundamental natural frequency, as a result of implementing each pattern shape and parameter variation, was the selection criterion, due to its importance during the launcher selection process. The best pattern from among the four alternatives was then selected, after having validated the computational methodology through implementing experimental modal analysis on a scaled down physical model of a primary load-bearing component of the structural design. From the findings, a significant mass reduction percentage of 23.15%, utilizing the proposed perforation concept, was achieved in the final parametric design iteration relative to the baseline unperforated case while maintaining the same fundamental frequency. Dynamic loading analysis was also conducted, utilizing both the baseline unperforated and the finalized perforated designs, to check its capability to withstand realistic launch loads through applying quasi-static loads. The findings show that the final perforated design outperformed the baseline unperforated design with respect to the maximum displacements, maximum Von Mises stresses, and also the computed margin of safety. With these encouraging outcomes, the perforated design concept proved that it could provide an opportunity to develop low-cost satellite structural designs with reduced mass.

The Role of Exercise Training on Low-Grade Systemic Inflammation in Adults with Overweight and Obesity: A Systematic Review

Low-grade systemic inflammation leads to critical alterations of several tissues and organs that can promote the appearance of non-communicable diseases, a risk that is increased in adults with obesity. Exercise training may counteract low-grade systemic inflammation, but there is a lack of consensus on how cytokines are modulated by training in adults with obesity. This study aimed of examining the effects of exercise training on circulating pro- and anti-inflammatory cytokines in adults with overweight and obesity, and whether exercise-induced fat mass reduction could mediate that effect. The search was conducted on Medline (Pubmed), SPORTDiscus and Web of Science databases from January 1998 to August 2021, using keywords pertaining to inflammation, exercise, and obesity. A total of 27 studies were selected, in which the circulating concentration levels of cytokines were analyzed. Endurance training (ET) decreased circulating CRP, IL-6 and TNF-α levels. TNF-α was reduced after resistance and concurrent training (CT), while IL-10 increased after resistance training (RT). Changes in IL-10 and CRP coincided with fat mass reduction, while decreased TNF-α levels were concomitant with changes in IL-6 and IL-10. Exercise training may reduce systemic low-grade inflammation profile in adults with overweight and obesity.

Structural Integrity of Polymeric Components Produced by Additive Manufacturing (AM)—Polymer Applications

In the work presented herein, the structural integrity of polymeric functional components made of Nylon-645 and Polylactic acid (PLA) produced by additive manufacturing (Fused Deposition Modelling, FDM) is studied. The PLA component under study was selected from the production line of a brewing company, and it was redesigned and analyzed using the Finite Element Method, 3D printed, and installed under real service. The results obtained indicated that, even though the durability of the 3D printed part was lower than the original, savings of about EUR 7000 a year could be achieved for the component studied. Moreover, it was shown that widespread use of AM with other specific PLA components could result in even more significant savings. Additionally, a metallic hanger (2700 kg/m3) from the cockpit of an airplane ATR 70 series 500 was successfully redesigned and additively manufactured in Nylon 645, resulting in a mass reduction of approximately 60% while maintaining its fit-for-purpose. Therefore, the components produced by FDM were used as fully functional components rather than prototype models, which is frequently stated as a major constraint of the FDM process.

EFFECT OF K-CARRAGEENAN ON MECHANICAL, THERMAL AND BIODEGRADABLE PROPERTIES OF STARCH–CARBOXYMETHYL CELLULOSE (CMC) BIOPLASTIC

Starch–carboxymethyl cellulose (CMC) bioplastics have limited mechanical properties. Carrageenan from seaweed is a potential reinforcement material for improving the mechanical properties of bioplastics. This study aimed to determine the effect of Kappa (κ)-carrageenan on the mechanical and thermal properties and biodegradability of starch–CMC bioplastics. In this study, carrageenan at concentrations of 0%, 10%, 15%, 20%, 25% and 30% was used. The melt-mixing process was conducted at 130 °C for 4 min, using a mixer and then hot-pressing (30 kgf/cm2) at 150 °C for 5 min. The results indicated that the higher κ-carrageenan concentration increased the strength of bioplastics up to 15.7 MPa. The fracture analysis via scanning electron microscopy–energy-dispersive X-ray spectroscopy indicated the distribution of sulfur (S) elements that described the dispersion of κ-carrageenan. The Fourier transform infrared spectroscopy spectra revealed that the interaction between the starch–CMC matrix and κ-carrageenan formed a tight hydrogen bond network. The lowest mass reduction observed by thermogravimetric analysis occurred in bioplastics with 25% carrageenan, decreasing by 48% compared with bioplastics without κ-carrageenan. The addition of κ-carrageenan was identified as not affecting the biodegradability of the bioplastics.

Superconductivity in the Layered Cage Compound Ba3Rh4Ge16

We report the synthesis and superconducting properties of a layered cage compound Ba3Rh4Ge16. Similar to Ba3Ir4Ge16, the compound is composed of 2D networks of cage units, formed by noncubic Rh–Ge building blocks, in marked contrast to the reported rattling compounds. The electrical resistivity, magnetization, specific heat capacity, and μSR measurements unveiled moderately coupled s-wave superconductivity with a critical temperature T c = 7.0 K, the upper critical field μ 0 H c2(0) ∼ 2.5 T, the electron-phonon coupling strength λ e−ph ∼ 0.80, and the Ginzburg–Landau parameter κ ∼ 7.89. The mass reduction with the substitution of Ir by Rh is believed to be responsible for the enhancement of T c and coupling between the cage and guest atoms. Our results highlight the importance of atomic weight of framework in cage compounds in controlling the λ e−ph strength and T c.

HO-1 in Bone Biology: Potential Therapeutic Strategies for Osteoporosis

Osteoporosis is a prevalent bone disorder characterized by bone mass reduction and deterioration of bone microarchitecture leading to bone fragility and fracture risk. In recent decades, knowledge regarding the etiological mechanisms emphasizes that inflammation, oxidative stress and senescence of bone cells contribute to the development of osteoporosis. Studies have demonstrated that heme oxygenase 1 (HO-1), an inducible enzyme catalyzing heme degradation, exhibits anti-inflammatory, anti-oxidative stress and anti-apoptosis properties. Emerging evidence has revealed that HO-1 is critical in the maintenance of bone homeostasis, making HO-1 a potential target for osteoporosis treatment. In this Review, we aim to provide an introduction to current knowledge of HO-1 biology and its regulation, focusing specifically on its roles in bone homeostasis and osteoporosis. We also examine the potential of HO-1-based pharmacological therapeutics for osteoporosis and issues faced during clinical translation.