Boronic acid and diol-containing polymers: how to choose the correct couple to form "strong" hydrogels at physiological pH.

Dynamic covalent hydrogels crosslinked by boronate ester bonds are promising materials for biomedical applications. However, little is known about the impact of the crosslink structure on the mechanical behaviour of the resulting network. Herein, we provide a mechanistic study on boronate ester crosslinking upon mixing hyaluronic acid (HA) backbones modified, on the one hand, with two different arylboronic acids, and on the other hand, with three different saccharide units. Combining rheology, NMR and computational analysis, we demonstrate that carefully selecting the arylboronic-polyol couple allows for tuning the thermodynamics and molecular exchange kinetics of the boronate ester bond, thereby controlling the rheological properties of the gel. In particular, we report the formation of "strong" gels (i.e. featuring slow relaxation dynamics) through the formation of original complex structures (tridentate or bidentate complexes). These findings offer new prospects for the rational design of hydrogel scaffolds with tailored mechanical response.

Methane emissions from contrasting urban freshwaters: Rates, drivers, and a whole-city footprint.

Global urbanization trends impose major alterations on surface waters. This includes impacts on ecosystem functioning that can involve feedbacks on climate through changes in rates of greenhouse gas emissions. The combination of high nutrient supply and shallow depth typical of urban freshwaters is particularly conducive to high rates of methane (CH4 ) production and emission, suggesting a potentially important role in the global CH4 cycle. However, there is a lack of comprehensive flux data from diverse urban water bodies, of information on the underlying drivers, and of estimates for whole cities. Based on measurements over four seasons in a total of 32 water bodies in the city of Berlin, Germany, we calculate the total CH4 emission from various types of surface waters of a large city in temperate climate at 2.6 ± 1.7 Gg CH4 /year. The average total emission was 219 ± 490 mg CH4  m-2  day-1 . Water chemical variables were surprisingly poor predictors of total CH4 emissions, and proxies of productivity and oxygen conditions had low explanatory power as well, suggesting a complex combination of factors governing CH4 fluxes from urban surface waters. However, small water bodies (area <1 ha) typically located in urban green spaces were identified as emission hotspots. These results help constrain assessments of CH4 emissions from freshwaters in the world's growing cities, facilitating extrapolation of urban emissions to large areas, including at the global scale.

Methanogens and Iron-Reducing Bacteria: the Overlooked Members of Mercury-Methylating Microbial Communities in Boreal Lakes.

Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the hgcA gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems. In the present study, we characterized the diversity of mercury-methylating microbial communities of boreal lake sediments using high-throughput sequencing of 16S rRNA and hgcA genes. Our results show that in the lake sediments, Methanomicrobiales and Geobacteraceae also represent abundant members of the mercury-methylating communities. In fact, incubation experiments with a mercury isotopic tracer and molybdate revealed that only between 38% and 45% of mercury methylation was attributed to sulfate reduction. These results suggest that methanogens and iron-reducing bacteria may contribute to more than half of the mercury methylation in boreal lakes.IMPORTANCE Despite the global awareness that mercury, and methylmercury in particular, is a neurotoxin to which millions of people continue to be exposed, there are sizable gaps in the understanding of the processes and organisms involved in methylmercury formation in aquatic ecosystems. In the present study, we shed light on the diversity of the microorganisms responsible for methylmercury formation in boreal lake sediments. All the microorganisms identified are associated with the processing of organic matter in aquatic systems. Moreover, our results show that the well-known mercury-methylating sulfate-reducing bacteria constituted only a minor portion of the potential mercury methylators. In contrast, methanogens and iron-reducing bacteria were important contributors to methylmercury formation, highlighting their role in mercury cycling in the environment.

Bleeding Risk of Antithrombotic Treatment in Patients on Hemodialysis.

BACKGROUND: The risk-benefit of antithrombotic treatment (ATT) has not been established in patients on dialysis. Our objective was to determine the influence of ATT on the risk of hemorrhage in patients on hemodialysis. METHODS: We included patients who began dialysis between 2003 and 2007. We determined the rates of fatal bleeding or bleeding leading to hospitalization or transfusion. RESULTS: Two hundred twenty-one patients were included. Over the follow-up period (45.5 ± 34 months), there were 76 hemorrhages in 52 patients. There were 10 fatal bleedings. The annual incidence of patients presenting with hemorrhagia was 6.2%. Bleeding occurred in 5.2% of those being treated with aspirin, 7% with acenocumarol, 12.3% with clopidogrel, 15.2% with aspirin + clopidogrel, 45.9% with anticoagulants + antiplatelets, 49.6% with low-molecular-weight heparin, and 3.9% without ATT. On multivariate analysis, masculine gender [hazard ratio (HR): 2.421; 95% confidence interval (CI), 1.261-4.650; P = 0.003], treatment with dicumarins (HR: 2.406; 95% CI, 1.013-5.718; P = 0.047), treatment with clopidogrel (HR: 2.697; 95% CI, 1.440-5.051; P = 0.002), and treatment with low-molecular-weight heparin (HR: 21.463; 95% CI, 9.067-50.806; P = 0.001) were independent predictors of bleeding. CONCLUSIONS: ATT increases the risk of bleeding in patients on hemodialysis. The incidence of hemorrhage varies with the type of antithrombotics used.

The influence of supervisor supportive behaviors on subordinate job satisfaction: the moderating effect of gender similarity.

This paper analyses the influence that different supervisor supportive behaviors have on subordinate job satisfaction, while considering the gender of individuals involved (supervisor and subordinate). The empirical evidence provided by a sample of 29,833 subordinates from 35 European countries collected by Eurofound through the European Working Condition Survey allows us to assert the following. First, subordinate job satisfaction depends on their perceptions about the supportive behaviors provided by their supervisors in terms of respect, giving recognition for a job well done, coordinating work, helping get the job done, and encouraging the professional development of the subordinate. Second, job satisfaction is affected by supervisor gender, although in the opposite direction as hypothesized, such that when the supervisor is a woman, subordinates report lower job satisfaction. Third, also contrary to our expectations, supervisor-subordinate gender similarity reduces, rather than increases, subordinate job satisfaction. Fourth, gender similarity, as expected, weakens the impact of several supervisor supportive behaviors on this job satisfaction (i.e., giving recognition, coordinating work, helping get the job done, and encouraging development). In terms of practical implications, this work suggests that it is advisable for supervisors to show supportive behaviors toward subordinates. In addition, because demonstrating respect at work is not moderated by gender similarity and seems to be the most impactful supportive behavior for enhancing job satisfaction, supervisors should pay particular attention to the respect of subordinates.

Improvement of Oil Valorization Extracted from Fish By-Products Using a Handheld near Infrared Spectrometer Coupled with Chemometrics.

A handheld near infrared (NIR) spectrometer was used for on-site determination of the fatty acids (FAs) composition of industrial fish oils from fish by-products. Partial least square regression (PLSR) models were developed to correlate NIR spectra with the percentage of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs) and, among them, omega-3 (ω-3) and omega-6 (ω-6) FAs. In a first step, the data were divided into calibration validation datasets, obtaining good results regarding R2 values, root mean square error of prediction (RMSEP) and bias. In a second step, all these data were used to create a new calibration, which was uploaded to the handheld device and tested with an external validation set in real time. Evaluation of the external test set for SFAs, MUFAs, PUFAs and ω-3 models showed promising results, with R2 values of 0.98, 0.97, 0.97 and 0.99; RMSEP (%) of 0.94, 1.71, 1.11 and 0.98; and bias (%) values of -0.78, -0.12, -0.80 and -0.67, respectively. However, although ω-6 models achieved a good R2 value (0.95), the obtained RMSEP was considered high (2.08%), and the bias was not acceptable (-1.76%). This was corrected by applying bias and slope correction (BSC), obtaining acceptable values of R2 (0.95), RMSEP (1.09%) and bias (-0.05%). This work goes a step further in the technology readiness level (TRL) of handheld NIR sensor solutions for the fish by-product recovery industry.

Spatial methane pattern in a deep freshwater lake: Relation to water depth and topography.

Freshwater lakes are regarded as important methane (CH4) sources, accounting for ~20% of natural emission. To improve the assessment of the global greenhouse effect, it is necessary to consider spatial variability within lakes. Here, CH4 concentrations in the water column and sediment layers, as well as the sediment CH4 production potentials and diffusive fluxes, were studied in the littoral, intermediate, and profundal zones of the medium-sized (425 ha), deep (maximum depth 69.5 m) Lake Stechlin (Germany). Sediment CH4 concentrations, production potentials and sediment-water interface diffusive fluxes showed significant spatial heterogeneity and were highest in the profundal zone. CH4 concentrations in the surface water did not differ among the studied locations, indicating a decoupling from the production sites in the sediment. The high amount of CH4 in profundal sediments that might potentially be released to the atmosphere is either trapped or oxidized within the water column, while the surface water dissolved CH4 is more related to the dynamics in the epilimnion. The divergence in sediment physical (water content, grain size) and chemical (organic matter quantity or quality, sulfate) properties across the lake leads to variations in CH4 dynamics which are restricted to deeper habitats in this type of lake.

Not far enough: Public health policies to combat COVID-19 in Mexico's states.

BACKGROUND: Mexican state governments' actions are essential to control the COVID-19 pandemic within the country. However, the type, rigor and pace of implementation of public policies have varied considerably between states. Little is known about the subnational (state) variation policy response to the COVID-19 pandemic in Mexico. MATERIAL AND METHODS: We collected daily information on public policies designed to inform the public, as well as to promote distancing, and mask use. The policies analyzed were: School Closure, Workplace Closure, Cancellation of Public Events, Restrictions on Gatherings, Stay at Home Order, Public Transit Suspensions, Information Campaigns, Internal Travel Controls, International Travel Controls, Use of Face Masks We use these data to create a composite index to evaluate the adoption of these policies in the 32 states. We then assess the timeliness and rigor of the policies across the country, from the date of the first case, February 27, 2020. RESULTS: The national average in the index during the 143 days of the pandemic was 41.1 out of a possible 100 points on our index. Nuevo León achieved the highest performance (50.4); San Luis Potosí the lowest (34.1). The differential between the highest versus the lowest performance was 47.4%. CONCLUSIONS: The study identifies variability and heterogeneity in how and when Mexican states implemented policies to contain COVID-19. We demonstrate the absence of a uniform national response and widely varying stringency of state responses. We also show how these responses are not based on testing and do not reflect the local burden of disease. National health system stewardship and a coordinated, timely, rigorous response to the pandemic did not occur in Mexico but is desirable to contain COVID-19.

Rapid Differentiation of Unfrozen and Frozen-Thawed Tuna with Non-Destructive Methods and Classification Models: Bioelectrical Impedance Analysis (BIA), Near-Infrared Spectroscopy (NIR) and Time Domain Reflectometry (TDR).

The performances of three non-destructive sensors, based on different principles, bioelectrical impedance analysis (BIA), near-infrared spectroscopy (NIR) and time domain reflectometry (TDR), were studied to discriminate between unfrozen and frozen-thawed fish. Bigeye tuna (Thunnus obesus) was selected as a model to evaluate these technologies. The addition of water and additives is usual in the fish industry, thus, in order to have a wide range of possible commercial conditions, some samples were injected with different water solutions (based on different concentrations of salt, polyphosphates and a protein hydrolysate solution). Three different models, based on partial least squares discriminant analysis (PLS-DA), were developed for each technology. This is a linear classification method that combines the properties of partial least squares (PLS) regression with the classification power of a discriminant technique. The results obtained in the evaluation of the test set were satisfactory for all the sensors, giving NIR the best performance (accuracy = 0.91, error rate = 0.10). Nevertheless, the classification accomplished with BIA and TDR data resulted also satisfactory and almost equally as good, with accuracies of 0.88 and 0.86 and error rates of 0.14 and 0.15, respectively. This work opens new possibilities to discriminate between unfrozen and frozen-thawed fish samples with different non-destructive alternatives, regardless of whether or not they have added water.

Development of chitosan nanocapsules containing essential oil of Matricaria chamomilla L. for the treatment of cutaneous leishmaniasis.

Matricaria chamomilla L. has been used for centuries in many applications, including antiparasitic activity. Leishmaniasis is a parasitic disease, with limited treatments, due to high cost and toxicity. Thus, there is a need to develop new treatments, and in this context, natural products are targets of these researches. We report the development of chitosan nanocapsules containing essential oil of M. chamomilla (CEO) from oil-in-water emulsions using chitosan modified with tetradecyl chains as biocompatible shell material. The nanocapsules of CEO (NCEO) were analyzed by optical microscopy and dynamic light scattering, which revealed spherical shape and an average size of 800 nm. Successful encapsulation of CEO was further confirmed by fluorescence microscopy observations taking advantage of the autofluorescence properties of CEO. The encapsulation efficiency was around 90%. The entrapment of CEO reduced its cytotoxicity towards normal cells. On the other hand, the CEO was active against promastigotes and intracellular amastigotes, exhibiting IC50 of 3.33 µg/mL and 14.56 µg/mL, respectively, while NCEO showed IC50 for promastigotes of 7.18 µg/mL and for intracellular amastigotes of 14.29 µg/mL. These results demonstrate that encapsulation of CEO in nanocapsules using an alkylated chitosan biosurfactant as a "green" stabilizer is a promising therapeutic strategy to treat leishmaniasis.

The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems: A latitudinal study across Europe.

Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64 °N. THg concentrations (0.06-2.78 ng L-1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8-159 pg L-1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.

Estado prostodóncico y salud bucal en pacientes que solicitaron reparaciones protésicas / Prosthodontics State and Oral Health in Patients that Requested Denture Repairs

Introducción: la salud bucodental es un componente de la salud general, por esto un mejoramiento de la salud oral puede influir positivamente en la calidad de vida. Objetivo: determinar el estado prostodóncico y aspectos de salud bucal, en los pacientes que solicitaron reparaciones protésicas. Método: se realizó un estudio transversal en pacientes que solicitaron reparaciones protésicas, en la Clínica Estomatológica Manuel Angulo Farrán, del municipio Holguín, desde febrero a diciembre de 2011. La muestra de 1 772 pacientes con prótesis removibles entre los 1 802 pacientes atendidos. Se realizó interrogatorio y examen clínico. Se utilizó el cálculo porcentual y el test de diferencia de proporciones. Los resultados se presentaron en tablas de distribución de frecuencia. Resultados: el mayor número de pacientes que solicitaron reparaciones pertenecían al sexo femenino (60,8 %) y al grupo de edad de 51 a 60 años (29,4 %). El tipo de prótesis que más se reparó, fue la parcial superior (59,8 %), el objeto de reparación más común fue la fractura completa (32,6 %). La frecuencia y métodos incorrectos de higiene bucal se evidenciaron en el 95,1 % y el 85,3 % de las prótesis se consideraron no aceptables. La estomatitis subprótesis fue la más frecuente de las alteraciones orales (71,4 %). Conclusiones: la mayoría de los pacientes acudieron a reparar prótesis consideradas no aceptables, presentaban hábitos de higiene incorrectos y lesiones en los tejidos bucales.

Introduction: an oral health improvement can influence positively in the quality of life because buccal health is a general health component. Objective: to determine the prosthodontics state and buccal health aspects in the patients that requested denture repairs. Method: a descriptive and cross-sectional study in patients requesting denture repairs at “Manuel Angulo" dental clinic from February to December 2011 was done. The sample comprised 1 772 patients with dentures among 1 802 patients. Interview and clinical examination were performed. Percentage calculation and difference of proportions test were used and the results were showed in simple frequency distribution charts. Results: the greatest number of patients requiring repairs was of female sex representing 60.8 % as well as the age group between 51 to 60 (29.4 %). Upper partial denture was the most fixed one, being the complete fracture the most common repaired object (32.6 %). The frequency and the improper way of oral hygiene were seen in 95.1 % of patients and 85.3 % of them were considered unacceptable. Denture stomatitis was the most frequent alterations detected in the buccal mucous (71.4 %). Conclusions: the majority of patients with repaired dentures that considered it unacceptable had poor hygiene habits and injury in oral tissues.

Patrón de consumo de refrescos en una población mexicana / Soft drink consumption patterns in a Mexican population

Para evaluar el patrón de consumo de los refrescos embotellados en el medio mexicano, se realizó una encuesta sobre el consumo de refrescos y bebidas refrescantes en usuarios (mayores de 10 años de edad) en la Ciudad de México (septiembre-octubre de 1993). Asimismo, se empleó una técnica estándar de laboratorio para establecer el pH de las bebidas. Los resultados mostraron que, en las 33 marcas de refrescos y 15 marcas de jugos y bebidas disponibles, los valores de pH fueron siempre marcadamente ácidos (entre 2.46 y 3.96). De los 2 008 respondentes (55.3 por ciento hombres, 44.7 por ciento mujeres; tasa de respuesta 90.1 por ciento), 1 657 (82.5 por ciento) afirmaron tomar refresco todos los días y 351 (17.5 por ciento) negaron su consumo. Aunque el alto consumo fue común en todos los grupos de edad, la ingestión referida pareció estar parcialmente asociada con la edad, siendo más considerable en los grupos más jóvenes. El número medio de refrescos bebidos por día fue 1.7, con una desviación estándar (DE) 1.3 y, por semana, fueron 9.3 (DE 9.9). El consumo informado de refresco pareció ser independiente de la escolaridad de los entrevistado. Si bien la proporción más alta de no consumidores de refresco se encontró en aquel grupo que consideró a los refrescos como un factor cariogénico muy importante, en general el grueso de los entrevistado indicó que el consumo de refrescos era un factor importante en la etiología de la caries. Asimismo, una mayor escolaridad estuvo más frecuentemente asociada a una atribución más preponderante de la importancia del papel de los refrescos en la caries

To evaluate soft drink consumption patterns in the Mexican population, the authors conducted a survey among people over 10 years of age in Mexico City (september-october 1993). Also, pH levels of commonly available beverages were measured using standard laboratory techniques. Results indicated that each one of the 33 soft drink brands and 15 brands of juices and beverages available, had markedly acidic pH values (between 2.46 and 3.96). Out of the 2 008 respondents (55.3% male, 44.7% female; response rate, 90.1%), 1 657 (82.5%) admitted drinking soft drinks daily, while 351 (17.5%) said they did not drink this type of beverages. Even though high consumption was frequent in all age groups, self-reported consumption was partially associated to age, being higher in the younger groups. The mean number of soft drinks ingested per day was reported to be 1.7, SD 1.3, and 9.3 per week SD 9.9. Self-reported consumption appeared to be independent of schooling level. Even though the largest proportion of non- consumers was found in the group that considered soft drinks to be a very important contributing factor to caries development, most interviewees agreed that soft drinks consumption was an important cariogenic factor. This attributed role was more prominent among interviewees with a higher level of schooling.