A novel 3D Cd(ii) coordination polymer generated via in situ ligand synthesis involving C–O ester bond formation

A novel 3D Cd(ii) coordination polymer {[Cd(ddpa)(2,2′-bpy)]·H₂O}_n (1) (H₂ddpa = 5,10-dioxo-5,10-dihydro-4,9-dioxapyrene-2,7-dicarboxylic acid, 2,2′-bpy = 2,2′-bipyridine) is hydrothermally synthesized in situ, and the influencing factors and mechanism for the in situ reaction are briefly discussed. The synthesis of 1 requires the formation of a new C–O ester bond. This current study confirms that metal ions and N-donor ligands play important roles in the domination of the in situ ligand from 6,6′-dinitro-2,2′,4,4′-biphenyltetracarboxylic acid (H₄dbta). Furthermore, the structure, thermal stability and photoluminescent property of 1 are also investigated.

A 3D Cd(ii) coordination polymer comprising ligand molecules not included in the original reaction mixtures but instead formed via in situ ligand synthesis involving a C–O ester bond.     

Sealing of anodized magnesium alloy AZ31 with MgAl layered double hydroxides layers

In this work, anodized magnesium alloy AZ31 with and without boiling water sealing was pre-prepared, and then MgAl-layered double hydroxide (LDH) films were fabricated on it through hydrothermal chemical conversion of the pre-prepared anodic layer. The morphology, structure, and composition of the films were characterized by XRD, SEM, EDS, FT-IR, XPS and GDOES. It was found that the porosity of the films was reduced after in situ fabrication of the LDHs. The effects of boiling water sealing treatment on the anodized substrate were also discussed. Moreover, the polarization curve, EIS, and immersion tests showed that LDHs fabricated on the anodized substrate with boiling water sealing treatment exhibited a significant long period of protection for the substrate.

In this work anodized magnesium alloy AZ31 with and without boiling water sealing was pre-prepared, and then MgAl-layered double hydroxide (LDH) films were fabricated on it through hydrothermal chemical conversion of the pre-prepared anodic layer.     

Characterizing the binding interaction of astilbin with bovine serum albumin: a spectroscopic study in combination with molecular docking technology

Astilbin (ASN) is a flavonoid compound isolated from the rhizome of Smilax china L. (Smilacaceae). It has many bioactivities, such as selective immunosuppression, antioxidant, anti-hepatic injury, etc., and is widely used in traditional Chinese medical treatments. The interaction of ASN with bovine serum albumin (BSA) was studied in a physiological buffer (pH = 7.40) using multi-spectroscopic techniques in combination with molecular docking methods. UV-vis absorption measurements proved that a ASN–BSA complex could be formed. Fluorescence data revealed that ASN could strongly quench the intrinsic fluorescence of BSA in terms of a static quenching procedure. The process of binding was spontaneous and the binding occurred mainly through hydrogen bonding and van der Waals forces. The distance r between donor (BSA) and acceptor (ASN) was calculated to be 4.80 nm based on Förster''s non-radiative energy transfer theory. The binding constant (K_a = 7.31 × 10⁴ mol L⁻¹) and the number of binding sites (n ≈ 1) at 298 K suggested that ASN only occupied one site in BSA with high affinity. Moreover, the results of molecular docking indicated that ASN was more likely to be located in site I (sub-domain IIA) of BSA. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that ASN induced conformational changes of BSA. The findings would be beneficial for research on the transportation, distribution and some important bioactivities of ASN in the human body.

The interaction of astilbin with bovine serum albumin was confirmed by multi-spectroscopic techniques and molecular docking methods.     

Fabrication and photocatalytic property of magnetic SrTiO3/NiFe2O4 heterojunction nanocomposites

Novel multifunctional SrTiO₃/NiFe₂O₄ nanocomposites were successfully fabricated via a two-step route. The as-prepared samples were characterized by using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), field-emission transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). The results indicate that the SrTiO₃/NiFe₂O₄ heterostructures are composed of SrTiO₃ spheroidal nanoparticles adhered to NiFe₂O₄ polyhedra. The heterojunction established in the composite material accelerates the process of electron–hole pair separation and boosts the photo-Fenton reaction. Among the samples, 15 wt% SrTiO₃/NiFe₂O₄ nanocomposites exhibit a powerful light response and excellent room temperature ferromagnetism. Subsequently, the photocatalytic degradation of RhB over the as-prepared samples was investigated and optimized, revealing that the 15 wt% SrTiO₃/NiFe₂O₄ nanocomposites exhibit the best photocatalytic activity and stability under simulated solar light irradiation. Furthermore, according to experimental results, the possible mechanism of improved photocatalytic activity was also proposed.

Photocatalytic degradation of RhB for all samples under simulated solar light illumination and absorption spectra of RhB over 15 wt% SrTiO₃/NiFe₂O₄ nanocomposites.     

Au–Ag and Pt–Ag bimetallic nanoparticles@halloysite nanotubes: morphological modulation,improvement of thermal stability and catalytic performance

In this study, Au–Ag and Pt–Ag bimetallic nanocages were loaded on natural halloysite nanotubes (HNTs) via galvanic exchange based on Ag@HNT. By changing the ratio of Au to Ag or Pt to Ag in exchange processes, Au–Ag@HNT and Pt–Ag@HNT with different nanostructures were generated. Both Au–Ag@HNT and Pt–Ag@HNT systems showed significantly improved efficiency as peroxidase-like catalysts in the oxidation of o-phenylenediamine compared with monometallic Au@HNT and Pt@HNT, although inert Ag is dominant in the composition of both Au–Ag and Pt–Ag nanocages. On the other hand, loading on HNTs enhanced the thermal stability for every system, whether monometallic Ag nanoparticles, bimetallic Au–Ag or Pt–Ag nanocages. Ag@HNT sustained thermal treatment at 400 °C in nitrogen with improved catalytic performance, while Au–Ag@HNT and Pt–Ag@HNT maintained or even had slightly enhanced catalytic efficiency after thermal treatment at 200 °C in nitrogen. This study demonstrated that natural halloysite nanotubes are a good support for various metallic nanoparticles, improving their catalytic efficiency and thermal stability.

Bimetallic Au–Ag@HNT and Pt–Ag@HNT nanocages showed significantly improved efficiency in the oxidation of o-phenylenediamine as peroxidase-like catalyst compared with corresponding monometallic nanoparticles.     

Molecular dynamics simulations of the self-organization of side-chain decorated polyaromatic conjugation molecules: phase separated lamellar and columnar structures and dispersion behaviors in toluene solvent

The self-organization of five model side-chain decorated polyaromatic asphaltene molecules with or without toluene solvent was investigated by means of atomistic molecular dynamic (MD) simulations. It was found that the organizational structure of polycyclic asphaltene molecules is significantly affected by the position and length of side chains. In the present study, two types of phase-separated stacking configurations, including the phase separated lamellar structure (PSLS) and the phase separated columnar structure (PSCS), were found. The PSLS and PSCS were also maintained in the presence of a small amount of toluene additive (30% wt fraction). When adding excess toluene molecules, the asphaltene molecules formed highly dispersed nanoaggregates. The dynamic properties of the π–π stacking structures in the PSLS and PSCS, as well as the nanoaggregates, were probed. It was found that the number and size of alkyl side chains significantly impacted the size and number of π–π stacking structures in the aggregates. Through tracking the structural evolution of the nanoaggregates, a possible dissociation mechanism of nanoaggregates is also suggested.

The self-organization of five model side-chain decorated polyaromatic asphaltene molecules with or without toluene solvent was investigated by means of molecular dynamic (MD) simulations.     

Psychometric properties of the Zephyr bioharness device: a systematic review

Background

Technological development and improvements in Wearable Physiological Monitoring devices, have facilitated the wireless and continuous field-based monitoring/capturing of physiologic measures in healthy, clinical or athletic populations. These devices have many applications for prevention and rehabilitation of musculoskeletal disorders, assuming reliable and valid data is collected. The purpose of this study was to appraise the quality and synthesize findings from published studies on psychometric properties of heart rate measurements taken with the Zephyr Bioharness device.

Methods

We searched the Embase, Medline, PsycInfo, PuMed and Google Scholar databases to identify articles. Articles were appraised for quality using a structured clinical measurement specific appraisal tool. Two raters evaluated the quality and conducted data extraction. We extracted data on the reliability (intra-class correlation coefficients and standard error of measurement) and validity measures (Pearson/Spearman’s correlation coefficients) along with mean differences. Agreement parameters were summarised by the average biases and 95% limits of agreement.

Results

A total of ten studies were included: quality ratings ranged from 54 to 92%. The intra-class correlation coefficients reported ranged from 0.85–0.98. The construct validity coefficients compared against gold standard calibrations or other commercially used devices, ranged from 0.74–0.99 and 0.67–0.98 respectively. Zephyr Bioharness agreement error ranged from ??4.81 (under-estimation) to 3.00 (over-estimation) beats per minute, with varying 95% limits of agreement, when compared with gold standard measures.

Conclusion

Good to excellent quality evidence from ten studies suggested that the Zephyr Bioharness device can provide reliable and valid measurements of heart rate across multiple contexts, and that it displayed good agreements vs. gold standard comparators – supporting criterion validity.

     

Acupressure Therapy for Acute Ankle Sprains: A Randomized Clinical Trial

Background

Ankle sprains occur frequently among young and active people, accounting for almost 2 million injuries per year. Previous reports suggest that acupressure therapy for acute ankle sprains may shorten the recovery time.

Combined spectroscopy methods and molecular simulations for the binding properties of trametinib to human serum albumin

Trametinib is a novel anticancer drug for treating metastatic cutaneous melanoma. The present study probed into the binding of trametinib to human serum albumin (HSA) through spectroscopy methods and molecular simulations. Trametinib could quench the fluorescence of HSA through static quenching which could be probed via fluorescence spectroscopy and time-resolved fluorescence. Thermodynamic parameters and docking results indicated that hydrogen bonds and van der Waals forces play crucial roles in this binding process, which exerts almost no effect on the HSA conformation under synchronous fluorescence, three-dimensional fluorescence, circular dichroism spectra, and molecular dynamics simulations. Site marker displacement experiments and molecular docking reveal that trametinib primarily binds to Sudlow site I of HSA. In addition, the trametinib–HSA interaction was hardly influenced by varying amino acid (glutamine, alanine, glycine, and valine) concentrations. This study can provide useful information for the pharmacokinetic properties of trametinib.

Probing the binding properties of trametinib to human serum albumin.