6,352 research outputs found

    Dry rainfed conditions are key drivers of the effect of conservation tillage and a nitrification inhibitor on N fate and N2O emissions: A field 15N tracing study

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    The sustainability of rainfed crops under semiarid conditions is threatened by low plant nitrogen (N) recovery as well as the potential loss of reactive N to the environment. A field 15N tracing experiment on barley (Hordeum vulgare L.) under rainfed conditions was carried out to study how different tillage management practices and the use of the nitrification inhibitor DMPSA affected the fate of N. The experiment consisted of a factorial combination of tillage (i.e., no tillage, NT, and conventional tillage, T) and fertilizer treatments (unfertilized control and ammonium nitrate, AN, with or without DMPSA). Single-labelled ammonium nitrate (15NH4NO3, 15AN, or NH415NO3, A15N) was applied at top-dressing to microplots at a rate of 80 kg N ha−1. Our results show out that DMPSA modulates the nitrification process from both fertilizer-N and endogenous soil-N (which was the main contributor to plant N uptake and N2O emissions), affecting soil residual N at the end of the cropping period (i.e., higher topsoil retention of 15AN in DMPSA-amended plots). Generally, cumulative N2O emissions from fertilizer were derived from 15AN rather than from A15N, thus confirming the site-specific choice of the source of synthetic N as an effective N2O mitigation strategy. Two months after harvest, a rewetting event produced a remarkable N2O emission peak that drove total cumulative N2O emissions and was also mainly derived from endogenous N. These results suggest that dry seasons could decrease N2O losses after fertilization while causing critical peaks after rewetting, thus potentially limiting the effectiveness of mitigation strategies. The average plant N recovery from the synthetic fertilizer was 22.6%, while the use of DMPSA combined with NT enhanced plant N uptake from endogenous soil-N. This could be a result of the improved crop development and plant N acquisition under NT, consistent with the decrease of soil N retention for A15N in the deeper layer at the end of the experiment in the nontilled plots. This study contributes to the mechanistic understanding of the effect of nitrification inhibitors and tillage on N2O emissions, soil N dynamics and N plant recovery, revealing relevant effects of both management strategies and a critical role of endogenous soil-N under dry rainfed conditions. It can be concluded that, under the conditions of our study, combining DMPSA with NT could help to improve plant N recovery, thus resulting in positive impacts on reactive N loss and climate change mitigation and adaptation

    Cu nanoparticle-loaded nanovesicles with antibiofilm properties. Part i: Synthesis of new hybrid nanostructures

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    Copper nanoparticles (CuNPs) stabilized by quaternary ammonium salts are well known as antimicrobial agents. The aim of this work was to study the feasibility of the inclusion of CuNPs in nanovesicular systems. Liposomes are nanovesicles (NVs) made with phospholipids and are traditionally used as delivery vehicles because phospholipids favor cellular uptake. Their capacity for hydrophilic/hydrophobic balance and carrier capacity could be advantageous to prepare novel hybrid nanostructures based on metal NPs (Me-NPs). In this work, NVs were loaded with CuNPs, which have been reported to have a biofilm inhibition effect. These hybrid materials could improve the effect of conventional antibacterial agents. CuNPs were electro-synthesized by the sacrificial anode electrolysis technique in organic media and characterized in terms of morphology through transmission electron microscopy (TEM). The NVs were prepared by the thin film hydration method in aqueous media, using phosphatidylcholine (PC) and cholesterol as a membrane stabilizer. The nanohybrid systems were purified to remove non-encapsulated NPs. The size distribution, morphology and stability of the NV systems were studied. Different quaternary ammonium salts in vesicular systems made of PC were tested as stabilizing surfactants for the synthesis and inclusion of CuNPs. The entrapment of charged metal NPs was demonstrated. NPs attached preferably to the membrane, probably due to the attraction of their hydrophobic shell to the phospholipid bilayers. The high affinity between benzyl-dimethyl-hexadecyl-ammonium chloride (BDHAC) and PC allowed us to obtain stable hybrid NVs c.a. 700 nm in diameter. The stability of liposomes increased with NP loading, suggesting a charge-stabilization effect in a novel antibiofilm nanohybrid material

    Predictors of diabetes risk in urban and rural areas in Colombia

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    Background: Nutritional habits low in fruits and vegetables and sedentary lifestyle are associated with a higher risk of developing Type 2 Diabetes (T2D). However, it is important to assess differences between urban and rural areas. This study aimed to analyze the associations between the risk of developing T2D and setting in the Colombian north coast in 2017. Methods: This cross-sectional study included 1,005 subjects. Data was collected by interviewing self-identified members of an urban community and a rural-indigenous population. The interaction terms were evaluated as well as the confounders. Then, adjusted binary logistic regressions were used to estimate the odds ratio (OR) and 95% Confidence Intervals (CI). Results: subjects with a high risk of T2D are more likely to belong to the urban setting (OR = 1.908; 95%CI = 1.201-2.01) compared with those with lower T2D after adjusting for age, Body Mass Index (BMI), physical activity, history of high levels of glycemia, and diabetes in relatives. Conclusions: Urban communities are more likely to have T2D compared with rural-indigenous populations. These populations have differences from the cultural context, including personal, and lifestyle factors.Peer reviewe

    Metabolic Responses of Two Assisted CPR Devices Versus Manual CPR during 1-Person CPR

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    Prolonged, one-person CPR is exhausting and associated with decayed CPR quality over time. Active compression-decompression-CPR (ACD-CPR) requires the rescuer to actively work during both phases of CPR. We evaluated the metabolic cost of manual CPR (M-CPR), ACD-CPR1, and ACD-CPR2 (with adhesive pad) during a 10-min resuscitation period. We hypothesized that the metabolic cost for the devices would be similar to M-CPR. Twenty (10 female) participants (23.5±3.5y, 165.8±25.6cm, 72.5±12.2kg) completed 3 randomized trials with performance feedback by investigators. Expired air was analyzed for estimations of metabolic cost via indirect calorimetry. Participants rested for 10 minutes before the baseline data collection followed by 10 min of CPR to simulate one-person CPR. Treatment effects were observed for VO2, METS, VCO2, HR, RR, blood lactate, and RPE. No such effect was observed for RQ, SBP, or DBP. VO2 (ml/kgBW/min) was significantly higher with ACD-CPR1 (17.8±1.4) vs. MCPR and ACD-CPR2 (15.9±0.9 and 14.2±1.1, respectively). Metabolic equivalent (MET) was significantly lower with ACD-CPR2 (4.1±0.3) vs. MCPR and ACD-CPR1 (4.7±0.3 and 5.1±0.4, respectively). All three groups’ blood lactate data differed significantly with ACD-CPR1 \u3e M-CPR \u3e ACD-CPR2. The RR required by the ACD-CPR1 during a 10 min CPR simulation is significantly higher than the ACD-CPR2 and M-CPR. No group differences were observed for RQ, SBP, or DBP. CPR performance metrics were averaged over the 10-min resuscitation period. RPE was significantly higher following ACD-CPR1 compared to both M-CPR and ACD-CPR2. The metabolic work required by the ACD-CPR2 during 10-min simulated one-person resuscitation (80/min) is far less than the ACD-CPR1. However, the ACD-CPR2 metabolic cost is similar to that of M-CPR, despite the latter method’s higher rate of compressions (110/min) and passive decompressions

    Staphylococcus aureus nasal colonization in Spanish children. The COSACO nationwide surveillance study

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    Objective: To assess the prevalence and risk factors for S. aureus and methicillin-resistant S. aureus (MRSA) nasal colonization in Spanish children. Methods: Cross-sectional study of patients <14 years from primary care centers all over Spain. Clinical data and nasal aspirates were collected from March to July 2018. Results: A total of 1876 patients were enrolled. Prevalence of S. aureus and MRSA colonization were 33% (95% CI 30.9–35.1) and 1.44% (95% CI 0.9–2), respectively. Thirtythree percent of the children (633/1876) presented chronic conditions, mainly atopic dermatitis, asthma and/or allergy (524/633). Factors associated with S. aureus colonization were age =5 years (OR 1.10, 95% CI 1.07–1.12), male sex (OR 1.43, 95% CI 1.17–1.76), urban setting (OR 1.46, 95% CI 1.08–1.97) and the presence of asthma, atopic dermatitis or allergies (OR 1.25; 95% CI: 1.093–1.43). Rural residence was the only factor associated with MRSA colonization (OR 3.62, 95% CI 1.57–8.36). MRSA was more frequently resistant than methicillin-susceptible S. aureus to ciprofloxacin [41.2% vs 2.6%; p<0.0001], clindamycin [26% vs 16.9%; p=0.39], and mupirocin [14.3% vs 6.7%; p=0.18]. None of the MRSA strains was resistant to tetracycline, fosfomycin, vancomycin or daptomycin. Conclusions: The main risk factors for S. aureus colonization in Spanish children are being above five years of age, male gender, atopic dermatitis, asthma or allergy, and residence in urban areas. MRSA colonization is low, but higher than in other European countries and is associated with rural settings

    Primary Angioplasty in a Catastrophic Presentation: Acute Left Main Coronary Total Occlusion—The ATOLMA Registry

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    Objectives. To determine the outcome predictors of in-hospital mortality in acute total occlusion of the left main coronary artery (ATOLMA) patients referred to emergent angioplasty and to describe the clinical presentation and the long-term outcome of these patients.Background. ATOLMA is an uncommon angiographic finding that usually leads to a catastrophic presentation. Limited and inconsistent data have been previously reported regarding true ATOLMA, yet comprehensive knowledge remains scarce.Methods. This is a multicenter retrospective cohort that includes patients presenting with myocardial infarction due to a confirmed ATOLMA who underwent emergency percutaneous coronary intervention (PCI).Results. In the period of the study, 7930 emergent PCI were performed in the five participating centers, and 46 of them had a true ATOLMA (0.58%). At admission, cardiogenic shock was present in 89% of patients, and cardiopulmonary resuscitation was required in 67.4%. All the patients had right dominance. Angiographic success was achieved in 80.4% of the procedures, 13 patients (28.2%) died during the catheterization, and the in-hospital mortality rate was 58.6% (27/46). At one-year and at the final follow-up, 18 patients (39%) were alive, including four cases successfully transplanted. Multivariate analysis showed that postprocedural TIMI flow was the only independent predictor of in-hospital mortality (OR 0.23, (95% CI 0.1-0.36),p<0.001).Conclusions. Our study confirms that the clinical presentation of ATOLMA is catastrophic, presenting a high in-hospital mortality rate; nevertheless, primary angioplasty in this setting is feasible. Postprocedural TIMI flow resulted as the only independent predictor of in-hospital mortality. In-hospital survivors presented an encouraging outcome. ATOLMA and left dominance could be incompatible with life
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