Waste-to-chemicals: Green solutions for bioeconomy markets.

In the fast-developing time, the accumulation of waste materials is always in an uptrend due to population increases and industrialization. This excessive accumulation in waste materials harms the ecosystem and human beings by depleting water quality, air quality, and biodiversity. Further, by use of fossil fuel problem-related global warming, greenhouse gases are the major challenge in front of the world. Nowadays, scientists and researchers are more focused on recycling and utilizing different waste materials like a municipal solid waste (MSW), agro-industrial waste etc. The waste materials added to the environment are converted into valuable products or green chemicals using green chemistry principles. These fields are the production of energy, synthesis of biofertilizers and use in the textile industry to fulfil the need of the present world. Here we need more focus on the circular economy considering the value of products in the bioeconomic market. For this purpose, sustainable development of the circular bio-economy is the most promising alternative, which is possible by incorporating the latest techniques like microwave-based extraction, enzyme immobilization-based removal, bioreactor-based removal etc., for the valorization of food waste materials. Further, the conversion of organic waste into valuable products like biofertilizers and vermicomposting is also realised by using earthworms. The present review article focuses on the various types of waste materials (such as MSW, agricultural, industrial, household waste, etc.), waste management with current glitches and the expected solutions that have been discussed. Furthermore, we have highlighted their safe conversion into green chemicals and contribution to the bioeconomic market. The role of the circular economy is also discussed.

Mechanical Properties of Al Foams Subjected to Compression by a Cone-Shaped Indenter.

Indentation tests and numerical simulations were conducted to investigate the effects of the indenter parameters (diameter and cone angle) and the relative density of Aluminum (Al) foams on the deformation mechanism of closed-cell Al foams, load response, and energy-absorbing capability. The results demonstrated that the densification occurred below the indenter, and cell tearing and bending occurred on both sides of the indenter, while the lateral plastic deformation insignificantly took place during the indentation tests. The load response and absorbed energy per unit volume dramatically increased with the cone angle of the indenter and the relative density of Al foams. However, the load response slightly increased but the absorbed energy per unit volume linearly decreased with the diameter of the indenter. Interestingly, the energy-absorption efficiency was independent of the diameter and cone angle of the indenter, and the relative density of Al foams as well. Our results suggest the indentation tests are recommended approaches to reflect the mechanical properties of closed-cell Al foams.

Experimental Investigation and Theoretical Modelling of a High-Pressure Pneumatic Catapult Considering Dynamic Leakage and Convection.

A high-pressure pneumatic catapult works under extreme boundaries such as high-pressure and rapid change of pressure and temperature, with the features of nonlinearity and gas-solid convection. In the thermodynamics processes, the pressure is much larger than the critical pressure, and the compressibility factor can deviate from the Zeno line significantly. Therefore, the pneumatic performance and thermo-physical properties need to be described with the real gas hypothesis instead of the ideal gas one. It is found that the analytical results based on the ideal gas model overestimate the performance of the catapult, in comparison to the test data. To obtain a theoretical model with dynamic leakage compensation, leakage tests are carried out, and the relationship among the leakage rate, pressure and stroke is fitted. The compressibility factor library of the equation of state for compressed air is established and evaluated by referring it to the Nelson-Obert generalized compressibility charts. Based on the Peng-Robinson equation, a theoretical model of the high-pressure pneumatic catapult is developed, in which the effects of dynamic leakage and the forced convective heat transfer between the gas and the metal wall are taken into account. The results from the theoretical model are consistent with the data from ejection tests. This research presents an approach to study the performance of a high-pressure pneumatic catapult with high precision.

Ion Doping Effects on the Lattice Distortion and Interlayer Mismatch of Aurivillius-Type Bismuth Titanate Compounds.

Taking Bismuth Titanate (Bi4Ti3O12) as a Aurivillius-type compound with m = 3 for example, the ion (W6+/Cr3+) doping effect on the lattice distortion and interlayer mismatch of Bi4Ti3O12 structure were investigated by stress analysis, based on an elastic model. Since oxygen-octahedron rotates in the ab-plane, and inclines away from the c-axis, a lattice model for describing the status change of oxygen-octahedron was built according to the substituting mechanism of W6+/Cr3+ for Ti4+, which was used to investigate the variation of orthorhombic distortion degree (a/b) of Bi4Ti3O12 with the doping content. The analysis shows that the incorporation of W6+/Cr3+ into Bi4Ti3O12 tends to relieve the distortion of pseudo-perovskite layer, which also helps it to become more stiff. Since the bismuth-oxide layer expands while the pseudo-perovskite layer tightens, an analytic model for the plane stress distribution in the crystal lattice of Bi4Ti3O12 was developed from the constitutive relationship of alternating layer structure. The calculations reveal that the structural mismatch of Bi4Ti3O12 is constrained in the ab-plane of a unit cell, since both the interlayer mismatch degree and the total strain energy vary with the doping content in a similar trend to the lattice parameters of ab-plane.

Predict human body indentation lying on a spring mattress using a neural network approach.

This article presents a method to predict and assess the interaction between a human body and a spring mattress. A three-layer artificial neural network model was developed to simulate and predict an indentation curve of human spine, characterized with the depth of lumbar lordosis and four inclination angles: cervicothoracic, thoracolumbar, lumbosacral and the back-hip (ß). By comparing the spinal indentation curves described by the optimal evaluation parameters (depth of lumbar lordosis, cervicothoracic, thoracolumbar and lumbosacral), a better design of five-zone spring mattresses was obtained for individuals to have an effective support to the main part of the body. Using such approach, an operating process was further introduced, in which appropriate stiffness proportions were proposed to design mattress for the normal body types of Chinese young women. Finally, case studies were undertaken, which show that the method developed is feasible and practical.