nature – Progress in Research

Agriculture: changing animal feed reduces consumption of natural resources

Posted on 26/01/202406/08/2024 by Erik Franco

A study published on the cover of Nature Food, the result of a collaboration between Politecnico di Milano and the University of Milan, highlights how the increased use of by-products in the feed sector (secondary products derived from the processing of primary crops such as cereals and sugar) in a circular perspective can lead to significant savings in the use of land and water resources and thus to more sustainable agri-food systems.

Underlying the work, signed by Camilla Govoni and Maria Cristina Rulli from Politecnico di Milano, Paolo D’Odorico from University of California at Berkeley and Luciano Pinotti from University of Milan, there is a thorough analysis and a search for strategies to reduce both the competition for natural resources between animal and human food production, and the unsustainable use of natural resources.

Not only does the use of agricultural by-products in animal diets decrease competition between sectors and pressure on resources, but it would also increase the availability of calories that can be directly earmarked for the human diet (eg cereals); if the saved resources are used for other purposes, including the production of plant foods lacking in current diets, it would improve food security in several countries, with healthier as well as more sustainable food choices
Camilla Govoni, researcher at the Department of Civil and Environmental Engineering

The study shows that an 11-16% substitution of energy-intensive crops currently used as animal feed (eg cereals) with agricultural by-products (eg cereal bran, sugar beet pulp, molasses, distillery residues and citrus pulp) would save approximately between 15.4 and 27.8 million hectares of soil, between 3 and 19.6 km³ and between 74.2 and 137.8 km³ of irrigation and rainwater.

The inter-sectoral decrease in the demand for cereals is of particular relevance at a time when the supply of these crops is facing serious shortages due to the combination of the ongoing war between Russia and Ukraine, the residual effects on the food supply of the Covid-19 pandemic, and a drop in harvests caused by increasingly frequent extreme events such as floods, droughts and heat waves induced by climate change.
Maria Cristina Rulli, Professor of Hydrology and Coordinator of the Glob3ScienCE Lab

The study online

Disegno di Laura Capellini

Innovative filters selected with x-rays

Posted on 26/09/202206/08/2024 by Erik Franco

Making molecular sieves and filters more efficient and safer is now possible thanks to the use of X-rays. The study has just been published in Nature Communications by a team of researchers from the Politecnico di Milano, the Grenoble Synchrotron and the University of Heidelberg.

Nanometric filters are tools with which we can capture unwanted, even very small molecules such as CO₂, other polluting gases and hazardous volatile organic substances. In the last few years sieves based on a metal-organic framework (MOFs), equipped with nanopores of varying sizes, shapes and characteristics that can be adapted to the type of molecule that you want to capture, are becoming more widespread.

Nowadays, the production of MOFs is limitless, but only a few have the ideal characteristics for efficient filtration. It is fundamental to be able to determine, for example, if only the desired molecules remain trapped in the pores and the efficiency of their sequestration. The trapped molecules, in fact, do not sort easily in the interstices and are difficult to see by X-ray diffraction, which often causes interpreting errors by overestimating or underestimating the efficacy of a certain material.

With this work, the methodology to be followed in order to locate molecules disorderly trapped in the interstices of the MOFs has become clear. In addition to a good quality of the crystalline matrix of the MOF (before and after its use), an accurate diffraction analysis is required. With our proposed protocol, the nanoporous materials can be analysed more accurately and their efficacy in filtration can be better established. Following the suggested procedure, a group of researchers from the Beijing Polytechnic University have been able to re-analyse several previous results concerning a MOF capable of trapping dioxin molecules. This is just one example of the possible applications in the field of materials engineering.
Piero Macchi, professor of the Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”

Recent studies have demonstrated how the MOFs could be used, for example, in the reduction of CO₂ in industrial exhaust gases, or as a water resource in highly dry and desert areas for their extraordinary capacity to absorb water from the atmosphere, even those with low humidity. For these and other uses, it is fundamental to determine the true capacity of the material to absorb the desired molecules.

Read the study

Discovery of a new phase transition in quasi-crystals

Posted on 07/03/202206/08/2024 by Erik Franco

A team of researchers from the Politecnico di Milano and the University of Rostock (Germany) has discovered and observed in the laboratory a new type of phase transition in a quasi-crystal made of laser light.

The discovery of this new phase transition in quasi-crystals represents a breakthrough in the understanding of some fundamental phenomena of quantum matter.

Quasi-crystals are structures that are not perfectly ordered, like crystals, but not completely disordered and are among the rarest structures in nature. In order to study their characteristics, the team of experimental physicists made in the laboratory a quasi-crystal with laser light that propagates in an intertwined manner in kilometre-long optical fibres: the complex dynamics of light in these fibres closely mirrors the quantum motion of electrons in the quasi-crystal. During the experiment, the researchers observed a triple phase transition, in which the topological properties, conductivity, and energy exchange between the quasi-crystal and its surroundings change abruptly but at the exact same time.

The discovery was published in the journal Nature and could pave the way for a holistic understanding of the inner workings of complex or engineered materials and their use in advanced phase-controlled materials-based applications.

The discovery of this new phase transition in quasi-crystals represents a breakthrough in the understanding of some fundamental phenomena of quantum matter. It may also pave the way for the development of a new technology and type of material unlike anything we have seen before, the properties of which we will be able to simultaneously control and modify at will. It would be a new form of matter much more flexible and controllable than the one we currently know about.
Stefano Longhi, professor at the Department of Physics of the Politecnico and co-author of the study

The article published in Nature

New model of agriculture and competition for water resources

Posted on 02/02/202206/08/2024 by Erik Franco

The ongoing agrarian transformation towards large-scale commercial agriculture often pursues the goal of increasing agricultural production through the expansion of irrigation. A study by Politecnico di Milano, published in Nature Communications, investigates how transnational Large Scale Land Acquisitions (LSLA), which play a major role in this process, can influence competition for water resources at the local scale.

Conducted in collaboration with the University of California, Berkeley, the University of Notre Dame, the Colorado State University, the University of Delaware and the Vrije Univeristeit in Amsterdam, the study combines hydrological and crop modelling, agricultural statistics and geo-referenced information on individual transnational LSLAs to assess the emergence of water scarcity associated with them.

The study found that competition for water has been exacerbated, to the detriment of local communities, for 105 of the 160 LSLAs considered (67% of the land acquired). On the one hand, the land of interest to investors is precisely that with preferential access to surface water and groundwater resources, and on the other hand, it was found that these agricultural investments have often been the premise for the planting of water-intensive crops and the expansion of irrigated crops.

Combining the growing demand for water with limited water resources is a key challenge for sustainable development,

comments Maria Cristina Rulli, Professor of Hydrology at Politecnico di Milano.

The use of water resources for agricultural production in large-scale land acquisitions can generate hydrological and social consequences for local users. To date, there have been only a few timid attempts to regulate, mainly on a voluntary basis, large-scale agricultural land acquisitions in the Global South and, unfortunately, recent progress in understanding the water dimension of these acquisitions has not yet been translated into a water governance perspective that takes into account any hydrological constraints, the need for water to ensure rural livelihoods, and environmental law.