Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Role of the support in the physico-chemical processes of impregnation of additive-impregnated hydrotreating catalysts

Ces travaux de recherche s’intéressent à la préparation des catalyseurs d’hydrotraitement qui sont largement utilisés dans les procédés de conversion du pétrole en carburant. Ces catalyseurs sont constitués d’une phase métallique sulfurée (généralement à base de Mo et Co) supportée sur un support poreux inorganique, communément l’alumine-gamma. Plus particulièrement, ces travaux ont pour objectif de décrire le rôle que joue la chimie de surface du support dans les processus physico-chimiques mis en jeu lors de l’étape d’imprégnation. En effet, cette étape est déterminante pour l'activité catalytique puisqu’à ce stade sont fixées la dispersion initiale des précurseurs métalliques, leur structure chimique et leur interaction avec le support.A cette fin, la chimie de surface du support a été modifiée par ajout d’une monocouche d’un additif inorganique (phosphore) ou organique (acide malonique et triéthylène glycol). Une approche multi-techniques, couplant caractérisations expérimentales (spectroscopie infrarouge et mesure de zétamétrie) et modélisation (PHREEQC), a été développée dans le cas du phosphore et de l’acide malonique afin de déterminer les sites de surface impliqués et les modes d’interaction (nature de liaison et denticité).Ensuite, l’impact de surface modifiées sur les interactions précurseurs-support ont été étudiées en imprégnant des solutions de complexité croissante (Mo, CoMo et CoMoP). Pour ce faire, une approche qualitative (spectroscopie Raman) et quantitative (désorption des catalyseurs) a été développée et les activités des catalyseurs ont été évaluées sur la réaction modèle d’hydrodésulfuration du 4-méthyldibenzothiophène (4-mDBT).Les résultats obtenus montrent que les additifs pré-imprégnés jouent un rôle principalement sur la dissolution du support et sur l’interaction avec les espèces molybdéniques faiblement adsorbées. La chimie de surface impacte majoritairement la proportion des espèces molybdéniques de surface plus que leur nature. Par ailleurs, la formation d’un complexe entre acide malonique et cobalt a été mis en évidence. La préparation des catalyseurs CoMoP/support avec la voie utilisant des hétéropolyanions (phosphomolybdates) montre l’importance de la nature de l’additif et de sa teneur pour le maintien de ces précurseurs.L’évaluation des performances catalytiques confirme l’interaction cobalt-acide malonique qui inhibe le rôle du promoteur et semble mettre en évidence un effet du TEG sur la morphologie de la phase active (ratio bords M/bords S diminué). Au final, le seul gain catalytique observé concerne les supports modifiés où les hétéropolyanions sont conservés montrant leur rôle majeur sur l’activité.This research work focuses on the preparation of hydrotreating catalysts which are widely used in refinery to produce cleaner fuels. These catalysts consist of a sulfided metal phase (usually based on Mo and Co) supported on an inorganic porous support, commonly gamma-alumina. More particularly, the aim of this work is to describe the role played by the surface chemistry of the support in the physico-chemical processes involved during the impregnation step. Indeed, this step is decisive for the catalytic activity since the initial dispersion of the metallic precursors, their chemical structure and their interaction with the support are fixed at this stage.For this purpose, the surface chemistry of the support was modified by a monolayer of an inorganic (phosphorus) or organic (malonic acid and triethylene glycol) additive. A multi-technique approach, combining experimental characterizations (infrared spectroscopy and zetametry measurements) and modeling (PHREEQC), was developed in the case of phosphorus and malonic acid in order to determine their modes of interaction (nature of binding and denticity) and the surface sites involved.Then, the impact of modified surfaces on the precursor-support interactions were studied by impregnating solutions of increasing complexity (Mo, CoMo and CoMoP). For this purpose, a qualitative (Raman spectroscopy) and quantitative (desorption of the catalysts) approach was developed and the activities of the catalysts were evaluated on the hydrodesulfurization of 4-methyldibenzothiophene (4-mDBT), a model reaction.The results obtained show that the major role played by the pre-impregnated additives occurs on the dissolution of the support and on the interaction with the weakly adsorbed molybdenum species. The surface chemistry impacts mainly the proportion of molybdenum species on the surface more than their nature. Moreover, the complexation of cobalt by the malonic acid has been highlighted. The preparation of CoMoP/support catalysts using heteropolyanions (phosphomolybdates) shows the importance of the nature of the additive and its content to maintain these precursors.The evaluation of the catalytic performances confirms the cobalt-malonic acid interaction which inhibits the role of the promoter and seems to highlight a morphology effect on the active phase (ratio M edge/S edge decreased) when the TEG is pre-impregnated. In the end, a catalytic gain is only obtained for the modified supports where the heteropolyanions are preserved showing their major role on the activity

Rôle du support dans les processus physico-chimiques d’imprégnation des catalyseurs d’hydrotraitement additivés

This research work focuses on the preparation of hydrotreating catalysts which are widely used in refinery to produce cleaner fuels. These catalysts consist of a sulfided metal phase (usually based on Mo and Co) supported on an inorganic porous support, commonly gamma-alumina. More particularly, the aim of this work is to describe the role played by the surface chemistry of the support in the physico-chemical processes involved during the impregnation step. Indeed, this step is decisive for the catalytic activity since the initial dispersion of the metallic precursors, their chemical structure and their interaction with the support are fixed at this stage.For this purpose, the surface chemistry of the support was modified by a monolayer of an inorganic (phosphorus) or organic (malonic acid and triethylene glycol) additive. A multi-technique approach, combining experimental characterizations (infrared spectroscopy and zetametry measurements) and modeling (PHREEQC), was developed in the case of phosphorus and malonic acid in order to determine their modes of interaction (nature of binding and denticity) and the surface sites involved.Then, the impact of modified surfaces on the precursor-support interactions were studied by impregnating solutions of increasing complexity (Mo, CoMo and CoMoP). For this purpose, a qualitative (Raman spectroscopy) and quantitative (desorption of the catalysts) approach was developed and the activities of the catalysts were evaluated on the hydrodesulfurization of 4-methyldibenzothiophene (4-mDBT), a model reaction.The results obtained show that the major role played by the pre-impregnated additives occurs on the dissolution of the support and on the interaction with the weakly adsorbed molybdenum species. The surface chemistry impacts mainly the proportion of molybdenum species on the surface more than their nature. Moreover, the complexation of cobalt by the malonic acid has been highlighted. The preparation of CoMoP/support catalysts using heteropolyanions (phosphomolybdates) shows the importance of the nature of the additive and its content to maintain these precursors.The evaluation of the catalytic performances confirms the cobalt-malonic acid interaction which inhibits the role of the promoter and seems to highlight a morphology effect on the active phase (ratio M edge/S edge decreased) when the TEG is pre-impregnated. In the end, a catalytic gain is only obtained for the modified supports where the heteropolyanions are preserved showing their major role on the activity.Ces travaux de recherche s’intéressent à la préparation des catalyseurs d’hydrotraitement qui sont largement utilisés dans les procédés de conversion du pétrole en carburant. Ces catalyseurs sont constitués d’une phase métallique sulfurée (généralement à base de Mo et Co) supportée sur un support poreux inorganique, communément l’alumine-gamma. Plus particulièrement, ces travaux ont pour objectif de décrire le rôle que joue la chimie de surface du support dans les processus physico-chimiques mis en jeu lors de l’étape d’imprégnation. En effet, cette étape est déterminante pour l'activité catalytique puisqu’à ce stade sont fixées la dispersion initiale des précurseurs métalliques, leur structure chimique et leur interaction avec le support.A cette fin, la chimie de surface du support a été modifiée par ajout d’une monocouche d’un additif inorganique (phosphore) ou organique (acide malonique et triéthylène glycol). Une approche multi-techniques, couplant caractérisations expérimentales (spectroscopie infrarouge et mesure de zétamétrie) et modélisation (PHREEQC), a été développée dans le cas du phosphore et de l’acide malonique afin de déterminer les sites de surface impliqués et les modes d’interaction (nature de liaison et denticité).Ensuite, l’impact de surface modifiées sur les interactions précurseurs-support ont été étudiées en imprégnant des solutions de complexité croissante (Mo, CoMo et CoMoP). Pour ce faire, une approche qualitative (spectroscopie Raman) et quantitative (désorption des catalyseurs) a été développée et les activités des catalyseurs ont été évaluées sur la réaction modèle d’hydrodésulfuration du 4-méthyldibenzothiophène (4-mDBT).Les résultats obtenus montrent que les additifs pré-imprégnés jouent un rôle principalement sur la dissolution du support et sur l’interaction avec les espèces molybdéniques faiblement adsorbées. La chimie de surface impacte majoritairement la proportion des espèces molybdéniques de surface plus que leur nature. Par ailleurs, la formation d’un complexe entre acide malonique et cobalt a été mis en évidence. La préparation des catalyseurs CoMoP/support avec la voie utilisant des hétéropolyanions (phosphomolybdates) montre l’importance de la nature de l’additif et de sa teneur pour le maintien de ces précurseurs.L’évaluation des performances catalytiques confirme l’interaction cobalt-acide malonique qui inhibe le rôle du promoteur et semble mettre en évidence un effet du TEG sur la morphologie de la phase active (ratio bords M/bords S diminué). Au final, le seul gain catalytique observé concerne les supports modifiés où les hétéropolyanions sont conservés montrant leur rôle majeur sur l’activité

Rôle du support dans les processus physico-chimiques d’imprégnation des catalyseurs d’hydrotraitement additivés

This research work focuses on the preparation of hydrotreating catalysts which are widely used in refinery to produce cleaner fuels. These catalysts consist of a sulfided metal phase (usually based on Mo and Co) supported on an inorganic porous support, commonly gamma-alumina. More particularly, the aim of this work is to describe the role played by the surface chemistry of the support in the physico-chemical processes involved during the impregnation step. Indeed, this step is decisive for the catalytic activity since the initial dispersion of the metallic precursors, their chemical structure and their interaction with the support are fixed at this stage.For this purpose, the surface chemistry of the support was modified by a monolayer of an inorganic (phosphorus) or organic (malonic acid and triethylene glycol) additive. A multi-technique approach, combining experimental characterizations (infrared spectroscopy and zetametry measurements) and modeling (PHREEQC), was developed in the case of phosphorus and malonic acid in order to determine their modes of interaction (nature of binding and denticity) and the surface sites involved.Then, the impact of modified surfaces on the precursor-support interactions were studied by impregnating solutions of increasing complexity (Mo, CoMo and CoMoP). For this purpose, a qualitative (Raman spectroscopy) and quantitative (desorption of the catalysts) approach was developed and the activities of the catalysts were evaluated on the hydrodesulfurization of 4-methyldibenzothiophene (4-mDBT), a model reaction.The results obtained show that the major role played by the pre-impregnated additives occurs on the dissolution of the support and on the interaction with the weakly adsorbed molybdenum species. The surface chemistry impacts mainly the proportion of molybdenum species on the surface more than their nature. Moreover, the complexation of cobalt by the malonic acid has been highlighted. The preparation of CoMoP/support catalysts using heteropolyanions (phosphomolybdates) shows the importance of the nature of the additive and its content to maintain these precursors.The evaluation of the catalytic performances confirms the cobalt-malonic acid interaction which inhibits the role of the promoter and seems to highlight a morphology effect on the active phase (ratio M edge/S edge decreased) when the TEG is pre-impregnated. In the end, a catalytic gain is only obtained for the modified supports where the heteropolyanions are preserved showing their major role on the activity.Ces travaux de recherche s’intéressent à la préparation des catalyseurs d’hydrotraitement qui sont largement utilisés dans les procédés de conversion du pétrole en carburant. Ces catalyseurs sont constitués d’une phase métallique sulfurée (généralement à base de Mo et Co) supportée sur un support poreux inorganique, communément l’alumine-gamma. Plus particulièrement, ces travaux ont pour objectif de décrire le rôle que joue la chimie de surface du support dans les processus physico-chimiques mis en jeu lors de l’étape d’imprégnation. En effet, cette étape est déterminante pour l'activité catalytique puisqu’à ce stade sont fixées la dispersion initiale des précurseurs métalliques, leur structure chimique et leur interaction avec le support.A cette fin, la chimie de surface du support a été modifiée par ajout d’une monocouche d’un additif inorganique (phosphore) ou organique (acide malonique et triéthylène glycol). Une approche multi-techniques, couplant caractérisations expérimentales (spectroscopie infrarouge et mesure de zétamétrie) et modélisation (PHREEQC), a été développée dans le cas du phosphore et de l’acide malonique afin de déterminer les sites de surface impliqués et les modes d’interaction (nature de liaison et denticité).Ensuite, l’impact de surface modifiées sur les interactions précurseurs-support ont été étudiées en imprégnant des solutions de complexité croissante (Mo, CoMo et CoMoP). Pour ce faire, une approche qualitative (spectroscopie Raman) et quantitative (désorption des catalyseurs) a été développée et les activités des catalyseurs ont été évaluées sur la réaction modèle d’hydrodésulfuration du 4-méthyldibenzothiophène (4-mDBT).Les résultats obtenus montrent que les additifs pré-imprégnés jouent un rôle principalement sur la dissolution du support et sur l’interaction avec les espèces molybdéniques faiblement adsorbées. La chimie de surface impacte majoritairement la proportion des espèces molybdéniques de surface plus que leur nature. Par ailleurs, la formation d’un complexe entre acide malonique et cobalt a été mis en évidence. La préparation des catalyseurs CoMoP/support avec la voie utilisant des hétéropolyanions (phosphomolybdates) montre l’importance de la nature de l’additif et de sa teneur pour le maintien de ces précurseurs.L’évaluation des performances catalytiques confirme l’interaction cobalt-acide malonique qui inhibe le rôle du promoteur et semble mettre en évidence un effet du TEG sur la morphologie de la phase active (ratio bords M/bords S diminué). Au final, le seul gain catalytique observé concerne les supports modifiés où les hétéropolyanions sont conservés montrant leur rôle majeur sur l’activité

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Complete blood counts with red blood cell determinants associate with reduced beta-cell function in seroconverted Swedish TEDDY children

Objectives: To investigate whether changes in complete blood count (CBC) in islet autoantibody positive children with increased genetic risk for type 1 diabetes are associated with oral glucose tolerance tests (OGTT) and HbA1c over time. Methods: The Environmental Determinants of Diabetes in the Young (TEDDY) study follows children with increased risk for type 1 diabetes in the United States, Germany, Sweden and Finland. In the current study, 89 Swedish TEDDY children (median age 8.8 years) positive for one or multiple islet autoantibodies were followed up to 5 (median 2.3) years for CBC, OGTT and HbA1c. A statistical mixed effect model was used to investigate the association between CBC and OGTT or HbA1c. Results: HbA1c over time increased by the number of autoantibodies (p <.001). Reduction in mean corpuscular haemoglobin (MCH) and mean cell volume (MCV) was both associated with an increase in HbA1c (p <.001). A reduction in red blood cell (RBC) counts (p =.003), haemoglobin (p =.002) and haematocrit (p =.006) levels was associated with increased fasting glucose. Increased red blood cells, haemoglobin, haematocrit and MCH but decreased levels of red blood cell distribution widths (RDW) were all associated with increased fasting insulin. Conclusions: The decrease in RBC indices with increasing HbA1c and the decrease in RBC and its parameters with increasing fasting glucose in seroconverted children may reflect an insidious deterioration in glucose metabolism associated with islet beta-cell autoimmunity

Deep hydrodesulfurization of 4,6-dimethydibenzothiophene over CoMoS/TiO2 catalysts: Impact of the TiO2 treatment

International audienceMesostructured titania as support for the CoMoS active phase in deep hydrodesulfurization (HDS) of 4,6-dimethydibenzothiophene (4,6-DMDBT) leads to an increase of the intrinsic HDS activity and a higher selectivity for direct desulfurization (DDS) for HDS reaction in contrast with the conventional CoMoS/alumina catalyst. The temperature treatment of the mesostructured TiO2 support, modifies the catalyst’s activity for the transformation of 4,6-DMDBT. The higher total and HDS activities were obtained after treatment at 380 °C corresponding to the higher specific surface area and to a mesostructured TiO2 material with a semi-crystalline anatase framework. Beyond 550 °C, the specific surface area decreases strongly corresponding to a complete crystallization of the mesopores walls into anatase structure. Moreover, the temperature under which the support is treated prior its impregnation has no impact on the selectivity of the transformation routes of the sulfur compound

From Research to Proof-of-Concept: Analysis of a Deployment of FPGAs on a Commercial Search Engine

FPGAs are quickly becoming available in data centres and in the cloud as a one more heterogeneous processing element complementing CPUs and GPUs. There are many reports in the research literature showing the potential for FPGAs to accelerate a wide variety of algorithms, which combined with their growing availability, would seem to also indicate a widespread use in many applications. Unfortunately, there is not much published research exploring what it takes to integrate an FPGA into an existing application in a cost-effective way and keeping the algorithmic performance advantages. Building on recent results exploring how to employ FPGAs to improve the search engines used in the travel industry, this paper analyses the end-to-end performance of the search engine when using FPGAs, as well as the necessary changes to the software and the cost of such deployments. The results provide important insights on current FPGA deployments and what needs to be done to make FPGAs more widely used. For instance, the large potential performance gains provided by an FPGA are greatly diminished in practice if the application cannot submit request in the most optimal way for the FPGA, something that is not always possible and might require significant changes to the application. Similarly, some existing cloud deployments turn out to use a very imbalanced architecture: a powerful FPGA connected to a not so powerful CPU. The result is that the CPU cannot generate enough load for the FPGA, which potentially eliminates all performance gains and might even result in a more expensive system. In this paper, we report on an extensive study and development effort to incorporate FPGAs into a search engine and analyse the issues encountered and their practical impact. We expect that these results will inform the development and deployment of FPGAs in the future by providing important insights on the end-to-end integration of FPGAs within existing systems

Structural Characterization of Phosphate Species Adsorbed on γ-Alumina by Combining DNP Surface Enhanced NMR Spectroscopy and DFT Calculations

International audienceObtaining an atomic-scale description of the chemical interactions of phosphates with an oxide support, such as γ-Al2O3, is essential to get a rational understanding of the role of phosphate additives for a great number of heterogeneous catalysts, as well as to improve the use of this element. Combining cutting-edge Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) techniques with Density Functional Theory (DFT) calculations, we provide an accurate molecular description of phosphate speciation on γ-Al2O3 surfaces for various P surface coverages after drying at 120 °C. Thanks to 31P double- and triple-quantum filtered NMR experiments as well as to 27Al–31P dipolar- and scalar-based correlation spectra, we demonstrate the presence of polyphosphates and of Al–O–P connectivities at the exposed facets of γ-Al2O3. DFT-based thermodynamics shows that phosphates (mono- or di-) are preferentially covalently bonded on the (1 1 0) γ-Al2O3 facet with high-dentation modes. These high-dentation modes are favored by entropy gain due to water desorption. We used the gauge-including projector-augmented wave (GIPAW) DFT method for 31P NMR chemical shifts calculations and propose a systematic identification of the various types of phosphates covalently or noncovalently bonded to the alumina surface. The calculations confirm the existence of polyphosphates as observed experimentally. Since the surface condensation into polyphosphates is endergonic, the presence of polyphosphates on the surface is likely to result from their direct adsorption in impregnation solution. The observed increasing concentration of polyphosphates with the coverage could be related to a less likely hydrolysis due to the reduced availability of sites to stabilize the fragmented oligomers. This understanding opens the way to a better control over the speciation of phosphate species that are known to be key in the preparation of supported catalysts over alumina