# Science

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With open facilities, the Brazilian Synchrotron Light Laboratory (LNLS) annually welcomes about 1200 Brazilian and foreign researchers, committed to more than 400 studies that result in approximately 200 articles published in scientific journals. Check out below some of the many investigations that have benefited from LNLS facilities.

# Research investigates the “concrete cancer”

Results may contribute to a better understanding of the chemical reaction that causes the degradation of concrete structures

Concrete is the most used material in construction and, consequently, one of the most consumed materials by humankind. It can be part of virtually every type of construction, from homes to large infrastructures such as bridges and dams. The strength and durability of concrete depend on the proportion of its constituents: Portland cement, sand, gravel and water.

Cement is a fine powder produced from limestone and clay that, with addition of water, becomes a binder paste that hardens through a series of complex chemical reactions. After hardening, the concrete retains its structure even if it comes back in contact with water. Over time, however, concrete can be degraded by many physical and chemical factors.

The alkali-silica reaction (ASR), also known as “concrete cancer”, is a chemical reaction between silica present in aggregates and alkaline hydroxides formed from cement constituents. The product of this reaction is a hygroscopic gel that expands in the presence of water, generating mechanical stress and widespread cracking.

# Monitoring food safety of marine fishes

Research investigates the concentration of chemical elements in commercial species

Marine fish are considered a source of high-quality protein and are rich in essential amino acids, fats, vitamins and many essential chemical elements such as calcium, iron and selenium. However, the presence of potentially toxic inorganic elements can cause everything from neurological and endocrine problems to increased cancer incidence.

Metals such as mercury, lead and cadmium are toxic even when consumed at low concentrations, and their adverse effects are magnified by accumulating in animal tissues. On the other hand, even elements like zinc and chromium, which play important roles in metabolism, can cause toxic effects if consumed in excess.

The accumulation of chemical elements in organisms depends on several factors, such as the type of element, the form of assimilation, the species and the metabolism in different tissues. For example, tissues with high metabolic rates, such as liver and kidney, may have a high concentration of metals, especially those with potential toxic effects.

Research investigates the addition of niobium to catalysts to improve alternative fuels

The increasing concentration of greenhouse gases in the atmosphere, caused by human activity, is considered the main cause for the increase in the average temperature of the planet. As a result, the search for renewable alternatives to fossil fuels has intensified, such as the transformation of biomass from agriculture into renewable fuels.

For example, pyrolysis oil, also known as bio-oil, is obtained by heating dry biomass to high temperatures, in the absence of oxygen, with subsequent cooling. Bio-oil is a complex mixture of organic compounds that can be used in place of petroleum to produce fuels and other chemicals.

# Enhancing solar energy production

Research investigates ways to convert titanium dioxide into a new photoactive material in the visible light range

The search for clean and renewable energy sources has intensified in recent years due to the increase in atmospheric concentration of greenhouse gases and the consequent increase in the average temperature of the planet.

One such alternative source is the conversion of sunlight into electricity through photovoltaic panels. The efficiency in this conversion depends on the intrinsic properties of the materials used in the manufacturing of the panels, and it increases year by year with the discovery of new and better materials. As such, solar energy is expected to become one of the main sources of electric energy by the middle of this century, according to the International Energy Agency (IEA).

# Analyzing the structural disorder of nanocrystals

Research applies unprecedented technique in Brazil for the investigation of crystalline nanoparticles

The development of faster and more efficient electronic devices, better catalysts for the chemical industry, alternative energy sources, and so many other technologies depends increasingly on the in-depth understanding of the behavior of materials at the nanometer scale.

The properties of particles on this scale may be completely different from the properties of the same material in its macroscopic version. In addition, nanoparticles of different sizes and shapes can have completely different characteristics, even though they are formed by the same material.

The possibility of regulating the optical and electrical properties of nanoparticles by controlling their composition, shapes and sizes opens the door to an immense variety of applications. In this context, nanocrystals - nanometric particles that have a crystalline structure - have attracted great interest.

# Control of light at the nanoscale

Research evaluates combination of graphene and hexagonal boron nitride for opto-electronic devices of the future

Photonics is the science that investigates phenomena related to light, such as its generation, transmission and detection. Its applications can be found in a wide range of technologies that directly impact our daily life: lasers used in surgery, fiber optics for data transmission, and screens of high definition TVs and smartphones. These advances are only possible by the in-depth knowledge of the interaction of light with supercompact electronic components.

The latest frontier of photonics is the production of nanoscale devices capable of transmitting information by means of light signals, called nanophotonic or optoelectronic devices. When compared to the already established electronic components, the new nanodevices will carry a greater volume of information at a faster pace.

# New materials for the reduction of vehicle pollution

Research develops nanostructured material with high oxygen storage and release capacity for the improvement of catalytic converters

Complete combustion of both fossil and biofuels generates carbon dioxide ($\rm CO_2$) and water as final products. However, incomplete combustion of these substances can occur in automobile engines, generating important pollutants such as carbon monoxide ($\rm CO$), hydrocarbons, and nitrogen oxides (such as $\rm NO$ and $\rm NO_2$).

To reduce the emission of these toxic substances, an equipment called a catalytic converter is used in the exhaust of vehicles. Materials called catalysts promote and accelerate chemical reactions without being consumed during the process. They retain on their surface the reactant molecules, weakening the bonds between the atoms and causing the pollutants to be converted into less harmful gases.

# Research identifies water reservoirs in sugarcane bagasse

Results contribute to improve processing technology and valorization of this resource

Sugarcane is cultivated in several countries around the world, mainly to produce sugar and alcohol obtained from the juice extracted during the milling process. The remaining fresh bagasse is a material rich in cellulose and lignin, but also in water. Even with the extreme efficiency of the operations in the sugarcane industry, after all the juice extraction stages in the mill, the fresh bagasse is still composed of almost 50% of water.

The remaining water in the bagasse has several important consequences. The extraction of sugar has efficiency between 94 and 98%. The remaining percentage remains trapped at the bagasse in some way associated with water. Thus, any percentage gain in this process can bring a million-dollar impact to the industry.

# Unraveling plants resistance to drought

Research investigates the chemical nanostructure of water conducting vessels

Plant cells are encased in a structure called the cell wall, composed mainly of cellulose and lignin. Among other functions, this wall gives structural stability to the cells and controls the entry of water, minerals and other substances. When they die, the cells leave behind their cell wall, forming different structures that support the plant giving rigidity to the stems and that facilitate the transport of substances from the roots to the leaves and vice versa. One such structure is the xylem: a continuous network of conduits about 100 micrometers in diameter that carries the water absorbed by the roots to the leaves.

# New possibilities against the HIV epidemic

Research identifies new antibodies with potent activity against virus and infected cells

The Human Immunodeficiency Virus type-1 (HIV-1) currently infects 37 million people worldwide, with an additional 2 million new infections each year. Following infection, the virus has a long period of latency, during which it multiplies without causing symptoms. HIV attacks the cells of the immune system, especially the cells called CD4+ T-lymphocytes, which are responsible for triggering the body's response chain against infections. Thus, by suppressing the action of the immune system, the virus destroys the body's ability to defend itself against other diseases, leading to the so-called Acquired Immunodeficiency Syndrome, or AIDS.

Even with the development of antiretroviral therapies that have improved quality of life and increased the life expectancy of patients with HIV/AIDS, it is widely accepted that the only way to effectively curb this devastating epidemic is through the development of an HIV-1 vaccine.