Xplor‐NIH is a popular software package for biomolecular structure determination from nuclear magnetic resonance (NMR) and other data sources. Here, some of Xplor‐NIH's most useful data‐associated ...energy terms are reviewed, including newer alternative options for using residual dipolar coupling data in structure calculations. Further, we discuss new developments in the implementation of strict symmetry for the calculation of symmetric homo‐oligomers, and in the representation of the system as an ensemble of structures to account for motional effects. Finally, the different available force fields are presented, among other Xplor‐NIH capabilities.
Non-invasive fetal electrocardiography (ECG) is based on the acquisition of signals from abdominal surface electrodes. The composite abdominal signal consists of the maternal electrocardiogram along ...with the fetal electrocardiogram and other electrical interferences. These recordings allow for the acquisition of valuable and reliable information that helps ensure fetal well-being during pregnancy. This paper introduces a procedure for fetal heart rate extraction from a single-channel abdominal ECG signal. The procedure is composed of three main stages: a method based on wavelet for signal denoising, a new clustering-based methodology for detecting fetal QRS complexes, and a final stage to correct false positives and false negatives. The novelty of the procedure thus relies on using clustering techniques to classify singularities from the abdominal ECG into three types: maternal QRS complexes, fetal QRS complexes, and noise. The amplitude and time distance of all the local maxima followed by a local minimum were selected as features for the clustering classification. A wide set of real abdominal ECG recordings from two different databases, providing a large range of different characteristics, was used to illustrate the efficiency of the proposed method. The accuracy achieved shows that the proposed technique exhibits a competitve performance when compared to other recent works in the literature and a better performance over threshold-based techniques.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•The effect of Ni content is analysed for CO2 methanation on CaO/Al2O3 and Na2CO3/Al2O3.•The temporal evolution of reactants and products is reported for storage and hydrogenation ...periods.•Adsorption and hydrogenation mechanisms onto dual function materials is proposed.•Maximum CH4 production of 185 μmol g−1 is observed for 10NiNa at 400 °C.•NiNa catalysts produced more CH4 and at lower temperatures than NiCa catalysts.
Anthropogenic CO2 emissions are one of the main causes of global warming. One alternative is the CO2 capture and valorization through catalytic processes to produce CH4 using dual function materials. In this work, Ni-15CaO/Al2O3 and Ni-10Na2CO3/Al2O3 catalyst have been synthesized varying the Ni loading, i.e. 5, 10 and 15 wt.%, and the impregnation methodology of the adsorbent and the metallic phase. All prepared samples have been physically and chemically characterized by adsorption-desorption of N2, XRD, TEM, H2 chemisorption, XPS, H2-TPR, CO2-TPD and TPSR with H2. The presence of CaO or Na2CO3 provides the catalyst with basic sites with different strength for the adsorption of CO2. Specifically, carbonates with lower stability are formed onto Na2CO3 in comparison to CaO. Besides, increasing Ni loadings slightly promote the decomposition of CO2 adsorbed species. The reducibility of Ni species is enhanced in the presence of the adsorbent and for increasing Ni loadings. CH4 formation during TPSR experiments is observed between 200–600 °C for CaO containing samples, whereas CH4 formation is observed in a narrower temperature range of 200–400 °C for Na2CO3 containing samples. A reaction scheme is proposed which describes the temporal evolution of reactants and products during the CO2 storage and hydrogenation cycles. The formation of CH4 increases with Ni loading. Maximum CH4 formation (142 μmol g−1) is observed for 15Ni15Ca sample at 520 °C. On the other hand, the formation of CH4 is higher (185 μmol g−1) operating at lower temperature, i.e. 400 °C, with 10Ni10Na sample containing a lower amount of nickel.
Summary
Background
Infants born small‐for‐gestational‐age (SGA) who develop post‐natal weight catch‐up are at risk for insulin resistance, central adiposity and cardiovascular disease in later life, ...even in the absence of overweight.
Objective
In young (age 3–6 years) non‐obese SGA children, we assessed arterial health (as judged by intima‐media thickness IMT) and abdominal fat distribution (subcutaneous, visceral, preperitoneal and hepatic components by magnetic resonance imaging MRI and/or ultrasound US) besides a selection of endocrine markers.
Methods
Comparisons of measures in SGA (n = 27) vs. appropriate‐for‐GA (AGA) children (n = 19) of similar height, weight and body mass index. Longitudinal outcomes (age 3–6 years) were carotid IMT (cIMT); fasting glucose, circulating insulin, IGF‐I and high‐molecular‐weight (HMW) adiponectin; abdominal fat partitioning by US. Cross‐sectional outcomes (age 6 years) were aortic IMT (aIMT) and abdominal fat partitioning by MRI.
Results
At 3 and 6 years, cIMT and IGF‐I results were higher and HMW adiponectin lower in SGA than AGA children; at 6 years, SGA subjects had also a thicker aIMT and more pre‐peritoneal and hepatic fat, and were less insulin sensitive (all P values between <0.05 and <0.0001). cIMT correlated positively with pre‐peritoneal fat, particularly at 6 years. Post‐SGA status and weight gain in early childhood (between 3 and 6 years) were independent predictors of cIMT at 6 years, explaining 48 % of its variance.
Conclusion
SGA children aged 3–6 years were found to have a thicker intima‐ media and more pre‐peritoneal and hepatic fat than AGA children of comparable size.
It is well known that increased abdominal fat is associated with cardiovascular (CV) risk. Perirenal fat has been recently associated with CV risk in adults. However, studies with children are ...lacking. We investigated the relationship of perirenal fat and other abdominal fat depots (including preperitoneal, intra-abdominal and subcutaneous fat) with carotid intima-media thickness (cIMT-a surrogate marker of CV risk) in prepubertal children, so as to identify novel markers that can be easily assessed and used in the early prevention of cardiovascular disease.
Subjects were 702 asymptomatic prepubertal Caucasian children (418 lean, 142 overweight and 142 obese) who were recruited in a primary care setting. Ultrasound measurements (perirenal, preperitoneal, intra-abdominal and subcutaneous fat and cIMT), clinical (body mass index (BMI) and systolic blood pressure) and metabolic parameters (insulin resistance (HOMA-IR), high molecular weight (HMW) adiponectin and serum lipids) were assessed.
Perirenal fat was associated with diverse metabolic and CV risk factors in all the studied subjects. However, in overweight and obese children, perirenal fat was mostly associated with cIMT (P<0.001) and was the only fat depot that showed independent associations with cIMT in multivariate analyses (overweight chidren: β=0.250, P=0.003, r
=12.8%; obese children: β=0.254, P=0.002, r
=15.5%) after adjusting for BMI, gender, age and metabolic parameters. Perirenal fat was also the only fat depot that showed independent associations with HMW-adiponectin in obese children (β=-0.263, P=0.006, r
=22.8%).
Perirenal fat is the main abdominal fat depot associated with cIMT, especially in overweight and obese children, and may thus represent a helpful parameter for assessing CV risk in the pediatric population.
Knowing the age of individuals in a population is crucial to devise appropriate conservation strategies, especially on endangered long-lived species such as sea turtles. Sea turtles do not have ...external morphologic characters that indicate their age; therefore, age has been estimated by indirect methods such as biometric measurements or skeletochronological analysis. Previous skeletochronological studies have determined that sea turtle age can be estimated with skeletal growth marks (GMs) produced by annual seasonality. This study focused on the skeletochronological analysis of known-age loggerheads reared under seminatural conditions, showing that sea turtles kept under natural photoperiod and seawater temperature seasonality and fed periodically, did not present visible GMs. However, the animals suffering health problems affecting their growth did exhibit GMs. This suggests that skeletochronological studies in sea turtles must be taken with caution at least at early life stages and for the northeast Atlantic loggerhead population. Additionally, this study showed that seawater temperature seasonality strongly influences sea turtles’ growth rates.
We report an in-depth study of the reduction of graphene oxide (GO) by in-situ thermal transmission electron microscopy (TEM) analysis. In-situ heating high-resolution TEM (HRTEM) imaging and ...electron energy-loss spectroscopy (EELS) measurements have been combined to identify the transformations of different oxygen functional groups, the desorption of physisorbed and chemisorbed water and the graphitisation as a function of the temperature in the range from 70 up to 1200 °C. A model for the general removal of water and OFGs is proposed based on different chemical and physical parameters that have been monitored. All this unique information provides a detailed roadmap of the thermal behaviour of GO at an extended range of temperature. This is not only of interest to understand the thermal reduction process of GO but also of critical relevance to the response of GO in applications when exposed to thermal effects.
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•A kinetic framework was provided for biomass compounds released in subW.•Secondary char was formed by increasing T from sugar soluble degradation products.•Maillard reactions between sugars and ...amino acids in subW led to faster reaction loss.•Dehydration products formation was retarded in sugar + amino acid systems.•Higher relative reactivity in Maillard reactions was observed for xylose over glucose.
A systematic kinetic study was conducted in subcritical water medium in the temperature range from 150 to 200 °C for pure glucose, xylose, proline and aspartic acid as well as binary mixtures of sugars + amino acids to understand the reaction kinetics and interactions among biomass components and to discern the influence of Maillard reaction (MR) on the overall reaction kinetics.
The main degradation products identified for glucose and xylose were the respective dehydration products, hydroxymethyl furfural and furfural, yielding an increasing solid residue with temperature (15.9 wt% at 200 °C) with an augmented heating value. The degradation of sugars and amino acids in binary systems was faster compared to pure compounds due to MR and the production of dehydration products was delayed when considering total sugar conversion. Higher relative reactivity in MR was observed for xylose over glucose showing also higher antioxidant activity.
Glutamine‐binding protein (GlnBP) displays an apo, “open” and a holo, “closed” crystal form, mutually related by a rigid‐body reorientation of its domains. A fundamental question about such ...large‐scale conformational transitions, whether the closed state exists in the absence of ligand, is controversial in the case of GlnBP. NMR observations have indicated no evidence of the closed form, whereas experimentally validated computations have suggested a remarkable ca. 40 % population. Herein, a paramagnetic NMR strategy designed to detect the putative apo‐closed species shows that a major population of the latter is highly improbable. Further, NMR residual dipolar couplings collected under three anisotropic conditions do not reveal differential domain alignment and establish that the average solution conformation is satisfied by the apo‐open crystal structure. Our results indicate that the computational prediction of large‐scale interdomain motions is not trivial and may lead to erroneous conclusions without proper experimental validation.
NMR paramagnetic relaxation enhancements and residual dipolar couplings indicate that apo glutamine‐binding protein strongly favors an open conformation in solution. The findings expose serious problems in the computational study of interdomain protein motions.
The sequence of prenatal growth restraint and postnatal catch-up growth may lead to hepato-visceral adiposity, insulin resistance and low-grade inflammation before the onset of puberty. In ...prepubertal children born appropriate for gestational age (AGA) or small for gestational age (SGA), we assessed potential relationships between the aforementioned sequence and liver volume.
The study population consisted of 86 children (41 AGA and 45 SGA with catch-up growth; age (mean±s.e.m.), 8.5±0.1 years), recruited into two prospective longitudinal studies. Anthropometry, endocrine-metabolic variables and inflammatory and hepatic markers were assessed, along with liver volume, hepatic adiposity and abdominal fat partitioning (by magnetic resonance imaging).
AGA and SGA children differed in hepato-visceral adiposity, but had similar liver volumes. Boys had larger livers than girls, and higher sex hormone binding globulin and inflammation markers. Liver volume correlated with height Z-score, body mass index Z-score, HOMA-IR (homeostasis model assessment-insulin resistance) and with subcutaneous and visceral fat, but not with birth weight Z-score or with hepatic adiposity. Height, visceral fat, gender and HOMA-IR were major determinants of liver volume, together explaining 61% of its variance.
The trajectory from prenatal restraint, via postnatal catch-up, to hepato-visceral adiposity and insulin resistance does not appear to be detectably influenced by prepubertal alterations of liver volume. Further follow-up will disclose the potential role of liver volume in the pubertal segment of this trajectory, and whether the augmented fat content and visceral adiposity in SGA subjects is followed by the development of metabolic syndrome and hepatic dysfunction in adulthood.
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