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The fabrication of complex low-dimensional quantum devices requires the control of the heteroepitaxial growth at the subnanometer scale. This is particularly challenging when the total thickness of stacked layers of device-active material becomes extremely large and exceeds the multi-μm limit, as in the case of quantum cascade structures. Here, we use the ultrahigh-vacuum chemical vapor deposition technique for the growth of multi-μm-thick stacks of high Gecontent strain-balanced Ge/SiGe tunneling heterostructures on Si substrates, designed to serve as the active material in a THz quantum cascade laser. By combining thorough structural investigation with THz spectroscopy absorption experiments and numerical simulations we show that the optimized deposition process can produce state-of-the-art threading dislocation density, ultrasharp interfaces, control of dopant atom position at the nanoscale, and reproducibility within 1% of the layer thickness and composition within the whole multilayer. We show that by using ultrahigh-vacuum chemical vapor deposition one achieves simultaneously a control of the epitaxy down to the sub-nm scale typical of the molecular beam epitaxy, and the high growth rate and technological relevance of chemical vapor deposition. Thus, this technique is a key enabler for the deposition of integrated THz devices and other complex quantum structures based on the Ge/SiGe material system.

biomaterials, blunting line, crack tip displacement, hyperelastic material

Additive Manufacturing, Digital Light Processing (DLP), Fracture Toughness, Photopolymerization

The integrity of soft materials against puncturing is of great relevance for their performance because of the high sensitivity to local rupture caused by rigid sharp objects. In this work, the mechanics of puncturing is studied with respect to a sharp-tipped rigid needle with a circular cross section, penetrating a soft target solid. The failure mode associated with puncturing is identified as a mode-I crack propagation, which is analytically described by a two-dimensional model of the target solid, taking place in a plane normal to the penetration axis. It is shown that the force required for the onset of needle penetration is dependent on two energy contributions, that are, the strain energy stored in the target solid and the energy consumed in crack propagation. More specifically, the force is found to be dependent on the fracture toughness of the material, its stiffness and the sharpness of the penetrating tool. The reference case within the framework of small strain elasticity is first investigated, leading to closed-form toughness parameters related to classical linear elastic fracture mechanics. Then, nonlinear finite element analyses for an Ogden hyperelastic material are presented. Supporting the proposed theoretical framework, a series of puncturing experiments on two commercial silicones is presented. The combined experimental–theoretical findings suggest a simple, yet reliable tool to easily handle and assess safety against puncturing of soft materials.

Os cuidados com a vegetação nos espaços públicos e privados é de extrema importância, pois visa garantir e proporcionar os serviços ambientais e ecossistêmicos. O objetivo foi realizar o diagnóstico da arborização presente no BioParque Zoopomerode. Para avaliação da vegetação, foi utilizado o método GAAU - Grau de Atenção para Árvores Urbana. Foram encontrados 664 indivíduos arbóreos, distribuídos em 76 espécies e 38 famílias. Para o diagnóstico fitossanitário, 571 indivíduos encontram-se com o grau de atenção BAIXO, 68 MÉDIO, 7 ALTO e 18 PRIORITÁRIO. Desse modo, conclui que a vegetação no BioParque, encontra-se com boas condições fitossanitárias, resultado das ações de manejo preventivo.

The hematopoietic U937 cells are able to differentiate into monocytes, macrophages, or osteoclasts when stimulated, respectively, with vitamin D3 (VD3), phorbol 12-myristate 13-acetate (PMA) or PMA plus VD3. We have previously demonstrated that magnesium (Mg) strongly potentiates the osteoclastic differentiation of U937 cells. In this study, we investigated whether such an effect may be ascribed to a capacity of Mg to modulate the monocyte differentiation of U937 cells and/or to an ability of Mg and VD3 to act directly and independently on the early phases of the osteoclastic differentiation. To address this issue, we subjected U937 cells to an individual and combined treatment with Mg and VD3 and then we analyzed, by flow cytometry and quantitative real-time polymerase chain reaction, the expression of a number of genes related to the early phases of the differentiation pathways under consideration. The results obtained indicated that Mg favors the monocyte differentiation of U937 cells induced by VD3 and at the same time, Mg contrasts the inhibitory effect that VD3 exerts on the osteoclastic differentiation in the absence of PMA. The crucial and articulated role played by Mg in diverse pathways of the osteoclastic differentiation of U973 cells is emphasized.

cutting,puncturing,soft material,sharpness,fracture mechanics

Photopolymerization,additive manufacturing,degree of cure,micromechanical model,mechanical properties,numerical simulations

Composting, to date, is one of the most used methods for the recovery of waste organic matter. Many are the organic wastes, sent to composting industrial plants, which come from municipal solid wastes (MSW), but many are also waste from the agri-food sector. Hemp industry has grown rapidly in recent years, both in terms of fiber and seeds production and inflorescences production for the pharmaceutical sector. The necessity of high crop productivity and high final product quality has led to the birth of many farms specialized in intensive field or greenhouses indoor hemp cultivation in which unsustainable and non-reusable substrates are used. Furthermore, hemp farms produce a lot of waste since part of the cultivated plants are not used for the market-ready products. Aim of this work is to explore the reuse of the hemp industry residues (from in field or indoor cultivation) to produce a soil conditioner that can be applied to the soil or mixed with the standard substrate to improve agronomic characteristics. In this case study, leaves and flowers from a hemp fiber cultivation are used. This work investigates the addition of biochar at the beginning of the decomposition process to study how biochar can improve both the decomposition process and the final product. An "aerated static pile" system has been simulated since this is one of the most used and easier-to-manage composting methods. Two compost bins of 1.3 m3 were built and a controlled aeration system was set up. Two tests were performed. The first test was necessary to regulate the air insufflation periods to obtain an excellent composting process. During the second test, instead, two different theses were tested to study the behavior of two different organic mixes. Thesis 1: leaves and flowers (LF); Thesis 2: leaves and flowers with the addition of 10% biochar v/v (LFB). Each bin was instrumented with 9 thermocouples through which the temperatures were logged throughout the composting cycle. The results showed that the system can produce a final quality product despite the small size of the compost bin. Temperatures remained high throughout the duration of the process and the trend was in line with the standard curves of the decomposition processes. During the tests, moisture content measurements were made and showed that the biochar was able to keep the mass wetter than the thesis without biochar, facilitating the proliferation of bacterial families. Furthermore, the LFB thesis has reached higher temperatures and kept them high for longer, which ensures the sterilization of the biomass (e.g. elimination of pathogens or fungi). It can therefore be concluded that composting hemp residues in small compost bins can be a valid alternative to the disposal of residues and the final compost biochar aided, called COMBI, can be used as improver in field or as substrate during the cultivation of potted plants, Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 161-169