Nanotechnologies for water sustainability

A Roadmap for Deployment of Nanotechnologies for meeting Water sustainability challenges in Latin America

Mona Arnold

María Lima-Toivanen

Martina Lindorfer

Ineke Malsch

María Teresa Alarcón

This roadmap is addressed to stakeholders dealing with nanotechnologies for water in Latin American countries. Considering the newness of the field and the early development stage of applications, the recommendations found here are more directed to policy-makers, academic experts and other experts dealing with knowledge transfer from university or research institutes to industry and public utilities and the water intensive industry, such as mining and agro-food. The present roadmap is the product of a 2-year multi-stakeholder research process in which we addressed the question of how nanotechnology based solutions to water related challenges (especially focusing on the Latin American context) could be produced in the future and made available to society. The research process approached five thematic clusters: (1) research, (2) policy making and funding, (3) education and training, (4) industry and investment and (5) ethical, legal and social aspects. The water applications focused on are potabilisation of water (chemical pollutants and disinfection), innovative solutions for desalination for drinking and process water and waste water treatment with recovery aspects. The roadmap focus on applications, research and development and gives recommendations for implementation considering the time horizon up to 2030 and considering efficient and responsible management of technological solutions.

From a global average perspective, Latin America is water-rich. With 500 million inhabitants or 8% of the world population distributed in 20 countries, the region possesses 31% of the freshwater resource in the world. However, this water is not equally distributed, 38 million people –nearly 7% of the population– are without access to safe water. Climate change can dramatically worsen the situation.

For example, Bradley et al. [1] present data on the effect of melting glaciers, especially in Southern Andes. As many large cities and irrigation systems in the Andes depend almost entirely on high-altitude glacier water stocks to complement rainfall during the dry season.  As these water  resource buffers shrink, further alternative water supplies may become very expensive. Less water intensive agricultural practices need to be installed and solutions for water recycling developed.  

To illustrate the need for innovative water solutions we have viewed the typical water management situation in a few Latin American countries. In Mexico, water scarcity is regarded as significant [2]. By sector, agriculture accounts for 77% of water use, industry 10% and domestic uses account for 13%.

Although agriculture represents the largest consumer, almost half of Mexico’s irrigation districts is said to be in a state of slow deterioration and leakages, leading to inefficient usage of water. Almost 70% of the country’s water is extracted from underground aquifers, with a rate of extraction far exceeding replenishment, and several of them in the northern regions are affected by natural arsenic and fluoride contamination.

Continual draining of water from such aquifers have resulted in Mexico City sinking 10 metres in the past century [3], clearly indicating that solutions for water saving and reuse are required. Industrial end users in Mexico include many sectors, namely: oil and gas, mining, petrochemical, pulp and paper, food and beverage and chemical industry.

According to Frost and Sullivan’s report [4], many industries have taken the decision to recycle water as a socially responsible action, and when water has an increasing price, many industries have chosen to install their own water treatment plants. The consequence of this is that the volume of treated water has doubled during the past 10 years. Still, in total, only 36 % of wastewater is treated [4].

Argentina has one of the highest levels of per capita water usage in the world at around 500 l/day [5]. Averagely the availability of water outstrips demand, yet 11% of the popula-tion still lacks piped water [6]. In contrast, yearly withdrawal capacity is 994 km³, and con-sumption is 745 m³ a person annually, more than three times the average of Brazil. Nevertheless, and not everyone in Argentina benefits from a good water supply. Areas in the North of the country, and in the poorest and most populous districts on the periphery of Buenos Aires, have little access to water. StillAgain, Central Argentina is the area most affected by arsenic contamination in the world [7].

In Chile only 4% of water withdrawals are used in the municipal sector, whereas agro and aquaculture accounts for 83%; industrial use accounts for 13%, of which 5,6% is used by the mining industry [8]. Industrial pollution is an issue both in Central and Northern regions of Chile and very often these discharges go untreated directly into river basins, lakes and irrigation channels. The impact of the mining industry is especially noted in the north, which is also an area highly affected by arsenic contamination [7].

General applications of nanotech-nologies for water fall under remediation of polluted water, po-tabilization of water, desalination and nanodevices (sensors for water quality monitoring). The benefits from the use of nanomaterials may derive from their enhanced reactivity, surface area, and sequestration characteristics. A variety of nanomaterials are in various stages of research and development (R&D), each possessing unique functionalities that are potentially applicable to the remediation of industrial effluents, groundwater, surface water and drinking water.

United Nation’s forecasts are quite alarming regarding the availability of drinking water in the future. It is foreseen an increase in the number of the world population affected by water scarcity, which is already around 40%,  when by 2050 at least one in four people are likely to be affected by recurring water shortages. Deployement of nanotechnologies for water in Latin America, as well as all over the world and especially in water scarce regions and lacking of proper sanitation, could help to achieve the targets of the United Nation’s Sustainable Development Goals. According to United Nation’s  whose Goal Number 6 aims to “Ensure access to water and sanitation for all”. Adequate policy actions in Latin America, following for example, the recommendations of the roadmap presented in this document, would set the examples needed for other regions of the planet.

Research Methods

The research process that culminated with the formulation of the roadmap for the deployment of nanotechnologies for water in Latin American countries, was carried out during the two year long project NMP-DeLA (Nanosciences, Nanotechnologies, Materials and New Production Technologies Deployment in Latin American Countries). It included desk research, bibliometric analysis and expert consultation through questionnaires, interviews, focus groups and panel discussions. Desk research was carried out in order to gather information on applications of nanotechnologies in the field of water and a bibliometric study, which provided information on the state-of-the-art of projects, most active institutions and researchers, and initiatives and enabling policies in Latin America.

Qualitative methods, such as consultation with experts from academia, industry and policy making, have been applied to analyse how much of current nanotechnology developments for application in water can deployed and what issues need to be addressed. Interpretation, discussion and validation of the first results of desk research and roadmap were performed with experts and the wider stake-holder community in the framework of NMP-DeLA events. These events consisted of two expert work-shops on water and energy, one held in November/2014 in Monterrey/Mexico (together with a summer school) and another held in brazil in 2015  and online consultation.

Following we present the findings of the applications of nanotechnologies for water with relevance for Latin America, the results of the bibliometric study and the roadmap, which was compiled during the process of research.

Nanotechnology for water with relevance to Latin America

Following is an overview of the state of the art and drivers, challenges and opportunities related to nanotechnology for water taking into account their relevance in Latin American countries.

Drinking water production (potabilisation)

Depending on the quality of the raw water, production of drinking water requires different steps using a combination of physical, chemical, physico-chemical and/or biological processes. Generally, surface waters require more comprehensive treatment than groundwater.

Potabilisation aims at removing organic matter, hazardous chemical pollutants, (including organic and inorganic compounds), bacteria and viruses from the water. A typical set of processes comprises screening for the removal of large floating items, coagulation or flocculation of organic matter, filtration to remove particles and bacteria, activated carbon filters to remove smell, taste and colour, advanced filtration for disinfection and chlorination.

Fine filtering using membrane technology, is also a possible option for advanced treatment of surface water for drinking water production. Membrane properties important for the operator of a water treatment plant are 1) high rejection of dissolved organics, 2)  low salt rejection, 3) low energy consumption and 4) stable performance after repetitive cleaning. For a potable water treatment plant, in order to be economically and operationally successful these four criteria have to be met.

As membrane processes are considered key components of advanced water purification and desalination technologies, there is a continuous search for new materials that are more selective and less prone to fouling. Incorporation of catalytic or magnetic nanoparticles into membranes derives highly efficient filters for the removal of chemical and microbiological impurities from drinking water that can also be used to lower the energy requirement of membrane filtration by adding antifouling qualities to the membrane.

In this regard, nanomaterials (e.g., carbon nanotubes, nanoparticles and dendrimers) are contributing to the development of more efficient and cost-effective water filtration processes (Table 1).

Source: Modified from Mohmood et al. [9].

Bioactive nanoparticles are playing an important role in water disinfection. Contamination from bacteria, protozoans, and viruses is possible in both ground and surface water. A variety of strong oxidants such as chlorine are normally used as disinfectants for pathogens in water treatment. However, these compounds tend to generate toxic by-products, such as trihalomethanes, haloacetic acids and aldehydes; so alternative disinfectants are also needed. Ozone (O₃), instead, does not have any residual effects, but produces unknown organic reaction products. For ultraviolet disinfection, longer exposure time is required for effectiveness, but there is no residual effect.

Several types of nanomaterials, such as silver, titanium oxide, magnesium, zinc and chitosan are capable of inactivating waterborne disease-causing microbes and viruses. Due to their charge capacity, they possess antibacterial properties. TiO₂ photocatalysts and metallic and metal-oxide nanoparticles are among the most promising nanomaterials with antimicrobial properties. A significant research effort continues to understand the mechanisms and enhance the efficiency of nanomaterials as antimicrobial agents [10].

Industrial waste water treatment and decontamination (remediation).

Oil and gas and mining industry are two water intensive sectors with high relevance in Latin America and water treatment is quickly emerging as one of the most significant challenges facing, for example the oil and gas industry. With large volumes of water used in the oil/gas production process, water is increasingly moving from an operational issue to one of strategic significance.

Nanomaterials for the remediation of water in the oil and gas industry should have a high sorption capacity for heavy metals, oil and other organic matters. Furthermore, in order to be economically feasible, the nanomaterial need to be easily recovered after wastewater treatment and cleaned for re-use. For example, porous boron nitride nanosheets have been reported to have potential for effective cleaning of oil mixed wastewater [11].

In the case of mining industry, today most applications of nanotechnology in mine water remediation have essentially followed the general application of nanomaterials in wastewater treatment and purification. Most research in this area has been performed at a laboratory scale and full scale implementation of nanotechnology by the mining industry is not expected yet in the next decade [12].

However, as water from mines contains potentially valuable minerals, the use of magnetic nanoparticles combined with recovery and regeneration is especially appealing. Magnetic nanoparticles for recovery of, e.g. gold from water solutions has been demonstrated at the laboratory scale.

Another topical object for nanoparticle-based solutions is the removal of arsenic contamination. Arsenic occurs at varying concentrations in the earth’s crust, from which it is mobilised by various biological and anthropogenic activities into groundwater and contaminates drinking water sources. Arsenic contamination of water is a global problem: it affects wells in countries with poor water management systems, is a common pollutant in mining wastewaters and bears high health risks. Arsenic incidents with severe health effects have been noted at least in Northern Chile, Mexico and Argentina. According to Larkins et al.  [13] affordable arsenic removal can be done by using synthetic clay. Also Zinc oxide nanoparticles could help remove arsenic using a point-of-source purification device. Approaches based on trapping arsenic contaminants on magnetic nanoparticles have also been developed [14].

Water Monitoring

Within the category of sensing and detection, of particular interest is the development of enhanced sensors to detect biological and chemical contaminants present at very low concentrations in water. Nanotechnology has the potential to facilitate the development of continuous monitoring devices capable of delivering real-time measurements at low cost and with improved specificity [15]. The high surface to volume ratio of nanoparticles enables surface chemical and physical phenomena that are exploited by new sensor devices. For example, sensitivity can increase due to increased conduction, detection limits can be lower, very small quantities of samples can be analysed, direct detection is possible without using labels, and some reagents can be eliminated [15, 16].

The beneficial characteristics of nanomaterials, such as enhanced reactivity, surface area and sequestration characteristics, form the basis of development work relating to highly sensitive water sensors. Examples of developing work include a gold nanocluster-based fluorescent sensor for highly sensitive and selective detection of cyanide in aqueous solution [17].  This involved the development of stabilized gold nanoclusters consisting of several tens of atoms, making them smaller than 1 nanometre in size, with a high affinity towards cyanide.

Moreover, semiconductor quantum dots (QDs), which are nanocrystals of inorganic semiconductors with diameters of 2–8 nm, have been used to develop optical sensors based on fluorescence measurements. This type of sensor could be used for environmental purposes for on-site identification of pathogens (like cholera toxin) in water [15].

Summary and  current challenges

Nanotechnology-derived materials such as nanoadsorbents, catalytic material, nanostructured and reactive membranes, as well as bioactive nanoparticles have been applied to water treatment. These materials are of interest due to their large surface area, efficiency in removing contaminants even at low concentrations, enhanced affinity for specific contaminants, catalytic potential, and high reactivity.  Table 2 below provides a list of applications demonstrating the general potential of nanomaterials in water technologies.

Table 2.  Applications demonstrating the general potential of nanomaterials in water technologies.

To become a reliable water treatment technology, a few challenges need to be met. So far, the environmental impact and toxicity of nanomaterials are poorly understood; therefore, the key challenge may be to gain regulatory and public acceptance for using nanomaterials in water purification. Other important issues include integrating nanomaterials in existing water purification systems and guaranteeing the availability of nanomaterials at scale, and at economically feasible prices. While the cost of different nanomaterial is decreasing, for example Brame et al. [18] reported that zero valent iron nanoparticles and TiO₂ can be produced at $0.14/g and $0.18/g respectively, some remain high, e.g. carbon nanotubes can be in the range of $ 300/g [19]. However, more important than the cost of nanomaterials per se is the cost normalized to the volume of water treated, a factor that currently is widely unknown.

In the context of treatment and remediation, nanotechnology has the potential to improve both water quality and quantity in the long run through the use of, for example, advanced membranes enabling water reuse or desalination.

The use of nanofibres and composite nanostructured membranes can help degrade a wide range of organic and inorganic contaminants in real field applications. However, most work is still taking place in research laboratories and there are only few commercial applications on the market. A better understanding of the formation of nanocomposite membranes will certainly be a step towards improving their performance. The deposition pattern of nanoparticles within the membrane matrices, and changes in the structure and properties of both nanomaterials and host matrices are among the priority concerns for field applications for water/wastewater treatment.

With regards to potabilisation (drinking water production), the practical application of nanoparticles can be limited by unknown side-effects caused by their release into the environment. A careful evaluation of the physical and chemical stability of immobilized particles in aqueous media (natural or effluents) will be necessary for its judicious use. Environmental and health risks and unknown factors related to the use of nanomaterials in water treatment have also hampered water technology companies’ interest in actively incorporating nanomaterials in their R&D and business lines.

Advances in nanotechnology for water in Latin America

Research and development activities focusing on nanotechnologies for water were gathered through bibliometric studies [20]. Those authors provide a list of leading experts, groups, institutions and main international collaborations with regards to expertise observed in three main water application categories: water desalination, contaminated water remediation and water potabilization. A summary of the main findings of the study of Invernizzi et al [20] is provided in the following paragraphs.

Overall, this research area is very new in LA countries. On the topic of water potabilization the first publications in the region appeared during the 1990s, and on the topic of water remediation, the first articles were published in the following decade (2000s). Of the three main water application categories, contaminated water remediation and water potabilization have almost equal output of publications (257 and 227 counts respectively as seen in table 3), whereas water desalination is the least researched of all.

Source: Based on Invernizzi et al [20]

Brazil and Brazilian institutions have the most outstanding output, followed by Mexico and Argentina. Taking a closer look at the production of some of the authors listed in the bibliometric map [20], one can conclude that the articles also described work on nanosensor development with applications in the water sector.

Interviews with researchers, although not having covered all the spectrum of work done in the field in Latin America, revealed that research and development nanoscience and nanotechnologies related to water deals with development of nanodevices for online sensing of metals and borate in water (Chile, Uruguay) and development of nanoparticles for water remediation based on sorption (Chile, Argentina), as well as catalytic degradation of nitrogen compounds, organic pollutants and reduction of mercorous chloride (Argentina).

Interviewed researchers mentioned clear connections between their work and the main social challenges. Their role does not only relate to technological solutions for improving the availability of safe, clean water and reducing environmental pollution. Developing solutions that utilizes national resources (foremost minerals) and increases their value, and teaching and advising young students and researchers in this thematic area were also mentioned as important factors for the overall development of the country. To note is that much ongoing research in nanoscience in LA relates to the generation and characterization (including stability in real environments) of nanomaterials for general applications, including environmental solutions. Although this work ultimately will serve the development of water solutions, the work as such is not specifically focused on a certain function.

As a specific contribution to the main social challenges for water, the removal of arsenic for potabilisation was mentioned. Arsenic contamination affects people in mining areas (e.g. in Chile, Mexico) and in areas with naturally high levels of arsenic in groundwater (e.g. Argentina). This challenge  was seen as important for several LA countries.

Focus group type interviews revealed that the high cost of the nanomaterials is considered a barrier to the application of nano-based solutions for societal challenges. Further investigation for lower cost solutions is needed. When moving from basic research towards applications of nanotechnologies, these should be aligned closely to solve concrete problems in Latin America and prove their effectiveness through real socio-economic impact. Demonstration projects to show the applicability of new innovations are crucial to enhance the deployment of new inventions. These demonstrations should be installed in nationally relevant environments such as drinking water production sites and mining water remediation.

Applied research with local relevance would involve, above all, potabilisation of water. For example,  Mexico is today the largest consumer of bottled water in the world and families sometimes spend as much as 10% of their incomes on water. This is double what the Inter-American Development Bank estimates they should be spending. Further demonstration cases with potential impact are solutions for remediation and reuse of industrial (mining, food, chemical) process water.

A detailed qualitative analysis and collection of contact data was conducted for those countries that were identified as remarkably productive by the bibliometric study [20]. A summary of results follows with the disclaimer that, due to the different amount and quality of information available, the information between countries is not easily comparable. So, briefly, we summarize the findings by country interms of research groups and focus in table 4.

Source: Based on Invernizzi et al. [20]

Recomendations and roadmap

The following recommendations addressed the thematic of nanotechnologies and focus on specific solutions that could be produced for solving some of the societal challenges related to water. Most of the recommendations were gathered by means of individual or group interviews with stakeholders, mainly researchers, who attended NMP-DeLA’s workshops; or responses from community of interest members to the questionnaire that was made available on the project’s website. The recommendations are related to research, policy and funding, and industry involvement and investment in order to address identified problems, and to improve the industrial competitiveness of the water sector in LA, as an indirect result.

• Building up a network of experts on water technology and nanospecialists, by organising conferences or seminars focused on nanotechnologies applied to water. Latin American researchers could be linked to European networks, including experts from the United States of America, in those conditions were collaborations are already in place.

• Jointly addressing problems that are common to member states of the region. As an example, Mexico, Argentina and Chile’s problems related to arsenic contamination.

• Involving affected industry and society in the search for solutions. Applied research should include the mining companies and local authorities with contaminated water problems. Social organizations should also be engaged in order to raise people´s awareness of water contamination.

• Applications of nanotechnology in water treatment should be developed following safety by design principles. End users should be involved from the beginning to make sure that solutions are useful to them.

• Building up involvement of African, Latin American and European experts together to achieve a critical mass. The nanotechnology community  could organise conferences on water treatment by solar energy, combining both energy and water in a nanotechnology framework, and bringing scientists together to solve common problems. Engagement with the International Water Association (IWA) could be useful in this regard, as the Association is doing work in Africa and bringing conferences to Africa.

• Apply nanotechnology in remediation of mining water effluents, especially membranes. The main problem is that there are few nanotechnologies for water applications at industrial scale, most are at lab-scale. These are still expensive and will take a long time to reach market. Another issue is solving the footprint of post-treatment and regeneration of used nanomaterials. For example the use of acetone to remove pollutant from nanocatalysts and how this wastewater is finally disposed of.

• Opportunities for cooperation between Europe and LA in scaling-up lab research and development on membranes and catalysts for arsenic, microbes etc.

• To scale up developments from lab scale or pilot scale to industrial scale in the long term. In general, nanotechnology for water and wastewater treatment is at the lab scale and it has not been deployed in real life. Its promising breakthroughs are foreseen in the coming years, so scaling up promising university developments for water purification to pilot or full scale in the long term is the aim. Furthermore, it is important to keep in mind the environmental fate, stability and toxicity.

• Point of use technologies in developing countries, to be installed, for example, in houses at point-of-use (e.g. sinks, or drinking water). Another potential application is, for example, the use of palladium as photocatalyst to be used for the catalytic reduction of nitrates. Point-of-use technologies will also be of interest to water desalination were technological innovation could enable small scale desalination.

In general, socio-economic factors such as poverty, poor living conditions and lack of access to clean water, pose serious regional obstacles in LA. Increased scarcity of (clean) water, and extreme weather events, induced by climate change as well as industrial pollution, will call for improved and affordable technological solutions. The opportunities for nanotechnologies for water in these settings could have a major positive contribution.

Nanotechnologies applied to water potabilisation, (industrial) waste water treatment and monitoring, will need to be developed from lab-scale demonstrations to regionally relevant applications, and progress to market is expected towards 2030. The main advantages of nanotechnology-derived solutions include more effective and cost-efficient solutions with less unwanted formation of hazardous by-products and waste. Below in table 5 we list recommendations followed by a suggested timeframe for their implementation.

References

[1] Vergara, W., Deeb, A.M., Valencia A.M., Bradley, R.S., et al. EOS Trans. Am. Geophys. Union  88, 261-268  (2007).

[2] Taylor, J.  2008 Mexconnect. http://www.mexconnect.com/articles/1497-water-crisis-availability-of-water-in-mexico

[3] Sample, I. The Guardian. http://www.guardian.co.uk/science/2004/may/06/thisweekssciencequestions. Accessed January 2015.

[4]  Frost and Sullivan. The Mexican Industrial Water and Wastewater Treatment Chemical Market. March 2013.

[5] World Bank. Argentina: Water Resources Management Policy. Elements for Sustainable Develop-ment in the XXI Century”. The World Bank. pp. 14–20 (2000).

[6] Valente M. 2011. Access to clean water in Argentina remains a work in progress, The Guardian http://www.theguardian.com/global-development/2011/dec/16/access-clean-water-argentina-progress. Accessed January 2015.

[7] Perez A. & Cirelli A. Arsenic and Water Quality Challenges in South America in Schneier-Madanes, G and Courel, M. (eds.), Water and Sustainability in Arid Regions  (Springer Science+Business Media B.V 275-293) 2010.

[8] FAO Aquastat. Aquastat Database http://www.fao.org/nr/water/aquastat/countries_regions/CHL/index.stm Accessed January 2015

[9] Mohmood I., Lopes, C., Lopes, I., Ahmad, I., Duarte, A. and Pereira, E. Environ Sci Pollut Res. 20, 1239–1260 (2013).

[10] Hossein, F., Perales-Perez, O., Hwang S., &  Román F.  Science of the Total Environment 466–467,  1047–1059 (2014).

[11] Lei, W., Portehault, D., Liu, D., Qin, S., Chen, Y. Nat. Commun. DOI: 10.1038/ncomms2818 (2013).

[12] Hu A. and Apblett A. (eds). Nanotechnology for Water Treatment and Purification. (Springer International Publishing. Switzerland) 2014.

[13] Larkins et al., Emerging Technologies to Benefit Farmers; P. Harrison, ed., “Emerging Challenges: Nanotechnology and the Environment,” Geo Yearbook: An Overview of Our Changing Environment 2007 (Nairobi, Kenya: United Nations Environment Programme, 2006), http://www.unep.org/yearbook/2007/PDF/7_Emerging_Challenges72dpi.pdf.

[15] Riu, J., Maroto., A. & Rius. X. Talanta  69 (2), 288–301 (2006).

[16] Long, F., Zhu, A., & Shi, H. Sensors  13(10), 13928-13948 (2013).

[17] Brame, J., Li, Q., & Alvarez, P.   Trends Food Sci Technol  22, 618–24 (2011).

[18] Liu Y., Ai, K., Cheng, X., Huo, L. & Lu, L   Advanced Functional Materials 16(6), 951–956 (2010).

[19] Nunez, S. Personal communication. Interview  Santiago Nunez, Director of Technological Development at the Ministry of Science, Technology and Telecommunication of Costa Rica / Martina Lindorfer, 2015.

[20] Invernizzi, N., Foladori, G., & Lindorfer, M. Mapping of Advanced Materials Deployment for Social Challenges: Health, Energy, Water, NMP-DeLA project deliverable D2.1, 2015, www.nmp-dela.eu

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Mona Arnold Ph.D. VTT Technical Research Centre of Finland, P. O. Box 1000, Espoo, Finland.   E-mail: maria.limatoivanen@vtt.fi

María Lima-Toivanen Ph.D. ZSI Centre for Social Innovation, Linke Wienzeile 246, 1150 Wien, Austria.

Martina Lindorfer Ph.D. ZSI Centre for Social Innovation, Linke Wienzeile 246, 1150 Wien, Austria.  E-mail: lindorfer@zsi.at

Ineke Malsch Ph.D. MTV Malsch TechnoValuation, Vondellaan 90, 3521 GH Utrecht, The Netherlands. E-mail: malschtechnovaluation@xs4all.nl

María Teresa Alarcón Ph.D. Centro de Investigación en Materiales Avanzados, Victoria 147 Nte., Zona Centro, 34000 Durango, México. E-mail: teresa.alarcon@cimav.edu.mxI

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