Solid State NMR Spectroscopy Studies of the Nature of Structure Direction of OSDAs in Pure-Silica Zeolites ZSM‑5 and Beta

2D ¹H DQ-SQ NMR spectra of zeolites TPA-OH-ZSM-5 and TEA-OH-ZSM-5 clearly demonstrate the specific spatial correlations between the SiO^–··HOSi hydrogen bonds within the framework and the alkyl chains of TPA⁺ and TEA⁺. For zeolite TPA-OH-ZSM-5,the 2D ¹H DQ-SQ NMR spectrum shows that the SiO^–··HOSi hydrogen bonds within the framework are spatially close to the methyl groups of TPA⁺ cations. For zeolite TEA-OH-ZSM-5, the 2D ¹H DQ-SQ NMR spectrum shows that the SiO^–··HOSi hydrogen bonds within the framework are spatially close to both the methyl and methylene groups of TEA⁺ cations. These observations imply that the position and distribution of the negative charge centers such as F anions, SiO^–··HOSi hydrogen bonds and T³⁺ atoms in the MFI framework are influenced by TPA⁺ or TEA⁺ cations for the strong electrostatic interactions. By analyzing the variable contact time ¹H–¹³C CP/MAS NMR experimental results, the ¹³C signal with δ = 10.6 ppm can be assigned to the methyl groups of TPA⁺ cations located in zigzag channels and the ¹³C signal with δ = 11.6 ppm can be assigned to the methyl groups of TPA⁺ cations located in straight channels. Both 2D ¹H DQ-SQ NMR spectrum and ¹H–¹³C CP/MAS NMR spectra of TEA-OH-Beta show that the SiO^–··HOSi hydrogen bonds within the framework are spatially further from the alkyl chains of TEA⁺ in Beta than those in ZSM-5, which indicates that van der Waals interactions play the dominant roles during the crystallization process of zeolite Beta. According to our NMR observations, it can be inferred that the nature of structure direction of OSDAs roots in the complex relationship between van der Waals interactions and electrostatic interactions in the inorganic–organic composites formed in the induction period

Mechano growth factor E peptide promotes rat bone marrow-derived mesenchymal stem cell migration through CXCR4-ERK1/2

<div><p></p><p>Mechano growth factor (MGF) is a splicing variant of insulin-like growth factor 1 (IGF-1). The unique C-terminal E domain of MGF (MGF-E) makes it distinct from the other variants of IGF-1. Our previous work demonstrated that MGF-25E induces the migration of rat bone marrow-derived mesenchymal stem cells (rMSCs) by altering their mechanical properties, which is accompanied by the activation of the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. However, the relationship between ERK1/2 activation and the change in mechanical properties has not been illustrated. In the present study, we determined that MGF-25E induced the migration of rMSCs by modulating CXCR4 to activate the ERK1/2 pathway. The analysis of the Young’s modulus and F-actin remodeling indicated that MGF-25E increased the stiffness and the F-actin polymerization of rMSCs through the activation of the CXCR4-ERK1/2 pathway. For the first time, this study clarified the signaling pathway that regulates the mechanical properties of rMSCs and is responsible for MGF-25E-promoted migration.</p></div

Responsiveness distributions among the eight elements of CHC responsiveness (n, %).

<p>Responsiveness distributions among the eight elements of CHC responsiveness (n, %).</p

Locations of the monitoring stations in Taizihe River.

<p>Locations of the monitoring stations in Taizihe River.</p

The framework of responsiveness evaluation in Wuhan community health services (CHS).

<p>The framework of responsiveness evaluation in Wuhan community health services (CHS).</p

Demographic characteristics of the respondents (n, %).

<p>Demographic characteristics of the respondents (n, %).</p

The result of matter element analysis in main stream of Taizihe River.

<p>The result of matter element analysis in main stream of Taizihe River.</p

Magnetism-Enhanced Monolith-Based In-Tube Solid Phase Microextraction

Monolith-based in-tube solid phase microextraction (MB/IT-SPME) has received wide attention because of miniaturization, automation, expected loading capacity, and environmental friendliness. However, the unsatisfactory extraction efficiency becomes the main disadvantage of MB/IT-SPME. To overcome this circumstance, magnetism-enhanced MB/IT-SPME (ME-MB/IT-SPME) was developed in the present work, taking advantage of magnetic microfluidic principles. First, modified Fe₃O₄ nanoparticles were mixed with polymerization solution and in situ polymerized in the capillary to obtain a magnetic monolith extraction phase. After that, the monolithic capillary column was placed inside a magnetic coil that allowed the exertion of a variable magnetic field. The effects of intensity of magnetic field, adsorption and desorption flow rate, volume of sample, and desorption solvent on the performance of ME-MB/IT-SPME were investigated in detail. The analysis of six steroid hormones in water samples by the combination of ME-MB/IT-SPME with high-performance liquid chromatography with diode array detection was selected as a paradigm for the practical evaluation of ME-MB/IT-SPME. The application of a controlled magnetic field resulted in an obvious increase of extraction efficiencies of the target analytes between 70% and 100%. The present work demonstrated that application of different magnetic forces in adsorption and desorption steps can effectively enhance extraction efficiency of MB/IT-SPME systems

Mean responsiveness scores of Wuhan CHCs.

<p>Mean responsiveness scores of Wuhan CHCs.</p

The correlation of NH₄⁺-N between neighboring monitoring sections in main stream of Taizihe River.

<p>The correlation of NH₄⁺-N between neighboring monitoring sections in main stream of Taizihe River.</p