Magnetite NPs@C with highly-efficient peroxidase-like catalytic activity as an improved biosensing strategy for selective glucose detection

This work reports the novel application of carbon-coated magnetite nanoparticles (mNPs@C) as catalytic nanomaterial included in a composite electrode material (mNPs@C/CPE) taking advantages of their intrinsic peroxidase-like activity. The nanostructured electrochemical transducer reveals an improved enhancement of the charge transfer for redox processes involving hydrogen peroxide. Likewise, mNPs@C/CPE demonstrated to be highly selective even at elevated concentrations of ascorbic acid and uric acid, the usual interferents of blood glucose analysis. Upon these remarkable results, the composite matrix was further modified by the addition of glucose oxidase as biocatalyst in order to obtain a biosensing strategy (GOx/mNPs@C/CPE) with enhanced properties for the electrochemical detection of glucose. GOx/mNPs@C/CPE exhibit a linear range up to 7.5 x 10-3 mol.L-1 glucose, comprising the entirely physiological range and incipient pathological values. The average sensitivity obtained at –0.100 V was (1.62 ± 0.05)x 105 nA.L.mol-1 (R2 = 0.9992), the detection limit was 2.0 x 10-6 M while the quantification limit was 6.1 x 10-6 mol.L-1. The nanostructured biosensor demonstrated to have an excellent performance for glucose detection in human blood serum even for pathological values.submittedVersionFil: Arana, Mercedes. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Arana, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Tettamanti, Cecilia Soledad. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica; Argentina.Fil: Tettamanti, Cecilia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Fisicoquímica de Córdoba; Argentina.Fil: Bercoff, Paula Gabriela. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Bercoff, Paula Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Rodríguez, Marcela Cecilia. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica; Argentina.Fil: Rodríguez, Marcela Cecilia. Consejo Nacional de Investigaciones Científicas y Técnica. Instituto de Investigaciones en Fisicoquímica de Córdoba; Argentina.Otras Ciencias Física

Experimental and modeling investigation on separation of methane from coal seam gas (CSG) using hydrate formation

The effects of temperature, pressure, initial promoter concentration and coal seam gas/liquid ratio on the separation of methane from coal seam gas were experimentally investigated. Low temperature, high pressure and high promoter concentration lead to high separation efficiency and high recovery rate of CH 4 , but reduce the CH 4 capture selectivity in hydrate. Experimental simulation of a three-stage separation shows that CH 4 can be concentrated from 34.6 to 81.3 mol% in the dissociated gas, while its content is only 7.2 mol% in the residual gas. An innovative model was established to predict the separation performance. The modeling results reasonably match the experimental data in predicting the effects of different influential factors, with an average relative deviation of 2.83%, the maximum relative deviation 11.2%, and the average relative variance 0.1044. The modeling results of a three-stage separation process include 81.0 mol% of CH 4 in the final dissociated gas and 5.5 mol% of CH 4 in the final residual gas. The recovery rate of CH 4 was 90.1 mol% and the separation factor was 73.0

The Effects of Reaction Parameters on the Corrosion Resistance of an Mg-Al Hydroxide Coating via in Situ Growth on a Biomedical Magnesium Alloy

An in situ Mg-Al hydrotalcite (LDH) film was prepared using a one-step hydrothermal method on the surface of a medical magnesium alloy. The importance and influence of the reaction parameters on the corrosion resistance of the LDH coatings were optimized and investigated through an orthogonal array and range analysis. The reaction parameters included the temperature, reaction time, pH, and concentration of the aluminum source. The relationship between the parameters and corrosion resistance performance of each coating was compared with the chemical composition, electrochemical corrosion current, and hydrogen evolution rate. Suitable reaction parameters were obtained. The morphology, element distribution, adhesion strength, and electrochemical properties of the preferred coatings were further analyzed and evaluated to optimize the treatment process. The results showed that temperature had the most significant impact on the quality of the LDH coating; a suitably high temperature, a longer reaction time, a higher aluminum source concentration, and a high pH were conducive to forming high-quality LDH coatings. There was an inverse relationship between the corrosion resistance and the LDH-to-Mg(OH)2 content ratio of the coatings. The optimal reaction parameters for this Mg-Al LDH coating on the substrate were 130 °C for 8 h at a pH of 13 using a 10 mM Al3+ solution

Reference markers of bone turnover for prediction of fracture: a meta-analysis

Abstract Objective To explore whether bone turnover biomarkers (BTMs), i.e., C-terminal telopeptide of type I collagen (CTX) and procollagen type I aminoterminal propeptide (PINP), are associated with fracture. Methods We searched electronic database including PubMed, Embase and Cochrane Library, and the reference lists of relevant articles published from inception to August 22, 2018. An updated meta-analysis was performed to assess the prediction value of CTX and PINP in fracture. Results Nine articles met our inclusion criteria and were included in the meta-analysis. The crude and adjusted effect size between PINP and fracture were extracted from two and five studies, respectively. PINP was not associated with fracture incidence without adjusting covariates (crude GR, 1.03; 95% CI, 0.91–1.17). After adjusting for potential confounders, PINP demonstrated a significant positive association with fracture (adjusted GR, 1.28; 95% CI, 1.15–1.42). In the subgroup analysis of studies after adjusting covariates, there were significant associations in women. Both the crude (1.16, 95%CI, 1.04–1.20) and adjusted GR (1.20, 95%CI, 1.05–1.37) shown positive relationships between CTX and fracture, which were extracted from four and six studies, separately. The sensitivity analysis confirmed the stability of the results. In the subgroup analysis of studies after adjusting covariates, there were significant associations in the subgroups of elderly, female, and hip fracture patients. Conclusions Our results indicate a statistically significant but modest association between BTMs (s-PINP or s-CTX) and future fracture risk after adjusting for BMD and clinical risk factors. The causal relationship between the two clinical conditions requires future validation with more standardized studies. Registration number CRD4201810787

The Adhesion Strength of Semi-Clathrate Hydrate to Different Solid Surfaces

The adhesion between a hydrate and a pipe wall is the main cause of hydrate deposition and blockage. In this study, the adhesion strength of semi-clathrate hydrate (tetrabutylammonium bromide hydrate) to four kinds of solid surfaces (E235B carbon steel, E355CC low alloy steel, SUS304 stainless steel, and polytetrafluoroethylene) was measured. This investigation reveals that the adhesion strength of the hydrate to a solid surface is negatively correlated with the wettability of the solid surface, which suggests that hydrophobic materials effectively reduced the hydrate adhesion to the pipe wall. The surface roughness showed different effects on the adhesion of the hydrate to hydrophilic or hydrophobic surfaces. To be specific, when the surface roughness increased from 3.2 µm to 12.5 µm, the hydrate adhesion strength to the hydrophilic surface of SUS304 increased by 123.6%, whereas the hydrate adhesion strength to the hydrophobic surface of polytetrafluoroethylene only increased by 21.5%. This study shows that low wettability and low surface roughness effectively reduce the critical rate required to remove hydrate deposition, which achieves the self-removal of hydrates. At the same time, it was found that the adhesion strength of the hydrate to surfaces increases with increasing subcooling. This investigation holds significant theoretical implications for designing self-cleaning surfaces for oil and gas pipes

Image_1_The ecological adaptation of the unparalleled plastome character evolution in slipper orchids.jpeg

Plastomes may have undergone adaptive evolution in the process of plant adaptation to diverse environments, whereby species may differ in plastome characters. Cypripedioideae successfully colonized distinct environments and could be an ideal group for studying the interspecific variation and adaptive evolution of plastomes. Comparative study of plastomes, ancestral state reconstruction, phylogenetic-based analysis, ecological niche modelling, and selective pressure analysis were conducted to reveal the evolutionary patterns of plastomes in Cypripedioideae and their relationship with environmental factors. The plastomes of the three evolved genera had reduced plastome size, increased GC content, and compacted gene content compared to the basal group. Variations in plastome size and GC content are proved to have clear relationships with climate regions. Furthermore, ecological niche modelling revealed that temperature and water factors are important climatic factors contributing to the distributional difference which is directly correlated with the climate regions. The temperature-sensitive genes ndh genes, infA, and rpl20 were found to be either lost/pseudogenized or under positive selection in the evolved groups. Unparalleled plastome character variations were discovered in slipper orchids. Our study indicates that variations in plastome characters have adaptive consequences and that temperature and water factors are important climatic factors that affect plastome evolution. This research highlights the expectation that plants can facilitate adaptation to different environmental conditions with the changes in plastome and has added critical insight for understanding the process of plastome evolution in plants.</p