Revamping SiO2 Spheres by Core–Shell Porosity Endowment to Construct a Mazelike Nanoreactor for Enhanced Catalysis in CO2 Hydrogenation to Methanol

Beyond the catalytic activity of nanocatalysts, the support with architectural design and explicit boundary could also promote the overall performance through improving the diffusion process, highlighting additional support for the morphology-dependent activity. To delineate this, herein, a novel mazelike-reactor framework, namely multi-voids mesoporous silica sphere (MVmSiO₂), is carved through a top-down approach by endowing core-shell porosity premade Stöber SiO₂ spheres. The precisely-engineered MVmSiO₂ with peripheral one-dimensional pores in the shell and interconnecting compartmented voids in the core region is simulated to prove combined hierarchical and structural superiority over its analogous counterparts. Supported with CuZn-based alloys, mazelike MVmSiO₂ nanoreactor experimentally demonstrated its expected workability in model gas-phase CO₂ hydrogenation reaction where enhanced CO₂ activity, good methanol yield, and more importantly, a prolonged stable performance are realized. While tuning the nanoreactor composition besides morphology optimization could further increase the catalytic performance, it is accentuated that the morphological architecture of support further boosts the reaction performance apart from comprehensive compositional optimization. In addition to the found morphological restraints and size-confinement effects imposed by MVmSiO₂, active sites of catalysts are also investigated by exploring the size difference of the confined CuZn alloy nanoparticles in CO₂ hydrogenation employing both in-situ experimental characterizations and density functional theory calculations.     

Differences in indentation and wear behaviors between the two sides of thermally tempered soda lime silica glass

Thermal tempering is an industrial process widely used to make soda lime silica (SLS) glass panels stronger and tougher. During the tempering process, the upper and bottom sides of the glass may experience different cooling rates, and thus, their properties could be different. This study characterized changes in surface composition and subsurface glass network structures as well as indentation and wear resistance properties of the air- and tin-sides of 6-mm-thick SLS window panels faced toward the upper and sliding roller sides during thermal tempering. The results showed that although the chemical and structural differences detected with X-ray photoelectron spectroscopy and specular reflection infrared spectroscopy are subtle, there are large differences in nanoindentation behaviors and mechanochemical wear properties of the SLS glass surface. The findings of this study provide further insights into the performance difference between the air- and tin-sides of the SLS glass panel treated with thermal tempering.     

Facile fabrication of hollow mesoporous bioactive glass spheres: From structural behaviour to in vitro biology evaluation

Bone defects accompanied by infection or inflammation can significantly delay the healing process. To simultaneously achieve controlled release of local antibiotics for infection control and bone healing, bone-implantable delivery systems have been considered as a promising strategy. This study aims to improve drug loading capacity of bone-implantable delivery systems by introducing hollow structure mesoporous bioactive glass nanospheres (HMBGs) through a sol–gel process. Particularly, such core–shell bimodal-porous structured nanoparticles were prepared through a sacrificing template using cetyltrimethylammonium bromide (CTAB) as surfactant. It was found that varying the amount of CTAB during the synthesis process is a simple and effective approach for tuning the particle size, morphology, and structure of HMBGs. For in vitro drug release, HMBGs could sustain storage and release of vancomycin hydrochloride (VAN) via diffusion-controlled mechanism, thereby inhibiting the bacteria growth in the subsequent bacterial study. Moreover, HMBGs incorporated with VAN provided a biomimetic microenvironment favored by cell adhesion and proliferation. These findings support the compatibility of HMBG nanoparticles with antibiotics and their potential application in the treatment of infectious bone defects.     

Simulation and analysis of dual-reflux pressure swing adsorption using silica gel for blue coal gas initial separation

A dual-reflux pressure swing adsorption (DR-PSA) process was proposed and simulated to initially separate the blue coal gas, aiming to capture carbon dioxide (CO₂) and enrich hydrogen (H₂), simultaneously. With a feed flow rate of 7.290 slpm, a light product reflux flow rate of 0.505 slpm and the heavy product reflux flow rate of 3.68 slpm, the developed DR-PSA process could capture CO₂ up to 64.01% with a recovery of 99.60% and enrich H₂ up to 34.66% with a recovery of 97.63% from the blue coal gas (36.2% N₂/28.5% H₂/13.9% CO/12.7% CO₂/8.7% CH₄). In addition, in order to optimize the process, the effects of various operating parameters on the DR-PSA process performance in terms of product purity and recovery were discussed in detail, including the feed position, the light product reflux ratio and the heavy product reflux ratio. Moreover, the dynamic distribution behaviors of pressure, temperature and gas-solid concentration were presented to explain and evaluate the process separation performance in depth under different operating conditions.     

Alginate–chitosan composite hydrogel film with macrovoids in the inner layer for biomedical applications

Making of a layered composite using two biopolymer gels with regularly aligned voids in the inner layer is described in this article. Calcium alginate constituted the inner layer, within which voids of 500 μm diameter were embedded in monolayer or in multiple layers using a fluidic device for bubbling. The chitosan without any additional crosslinker was used to form the outer layer. The layered structure enabled compartmentalization of drug hold-up, and differential release rates. These aspects were reviewed using bovine serum albumin and vitamin B₁₂ as model solutes. The presence of voids at the inner layer of alginate increased the uptake, raising the level of absorptivity to more than 4000%. The composite film could hold two solutes at a time. The one, held inside the alginate layer started releasing only after 1 h of dipping in the release media. The adhesive strength between layers and the response of the composite film to compressive deformation are studied here. The effect of single or multiple layers of voids in the inner layer is reviewed. The slowing of degradation rate due to chitosan-encapsulation is experimentally determined. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47599.     

Synthesis of mesoporous core-shell structured GdPO_4:Eu@SiO_2@mSiO_2 nanorods for drug delivery and cell imaging applications

Mesoporous GdPO_4:Eu@SiO_2@mSiO_2 core-shell nanorods(NRs) were prepared by a facile two-step method.First,the monodispersed GdPO_4:Eu NRs were obtained on a large scale via a facile precipitation method,then mesoporous silica was wrapped onto their surface through hydrolysis of tetraethylorthosilicate(TEOS).The XRD result indicates that the as-prepared GdPO_4:Eu NRs core has hexagonal phase.The FTIR and the N_2 adsorption/desorption isotherm analysis confirm the successful coating of mesoporous silica.The TEM images show that the obtained GdPO_4:Eu@SiO_2@mSiO_2 NRs exhibit uniform monodisperse core-shell structure with a nanorod core(length of 200 nm;width of 20 nm),and mesoporous silica shell of 15 nm.Under excitation of 274 nm,GdPO_4:Eu@SiO_2@mSiO_2 NRs show strong red luminescence from ~5 D_0→~7 F_J(J=1,2,3 and 4) transitions of Eu~(3+).Furthermore,the GdPO_4:Eu@-SiO_2@mSiO_2 NRs exhibit obvious T_1 enhancement effect due to paramagnetism of Gd~(3+).The drug loading capacity and pH-sensitive releasing behavior of the as-prepared GdPO_4:Eu@SiO_2@mSiO_2 NRs were studied by using doxorubicin(DOX) as model drug.The excellent biocompatibility of GdPO_4:Eu@-SiO_2@mSiO_2 NRs was demonstrated by MTT assay.Taken together,the mesoporous GdPO_4:Eu@-SiO_2@mSiO_2 NRs may be potentially applied in fields of drug delivery and dual-modal imaging.     

分散剂B-52对白炭黑/天然橡胶复合材料性能的影响

通过机械共混法制备白炭黑/天然橡胶(NR)复合材料,研究分散剂B-52用量对白炭黑/NR复合材料性能的影响。结果表明:随着分散剂B-52用量的增大,复合材料的t_(10)和t_(90)呈现出先延长后缩短的趋势,结合胶含量和表观交联密度提高,综合物理性能先提高后有所降低;当分散剂B-52用量为2份时,复合材料的综合物理性能最佳。     

Selective molecularly imprinted polymer nanofiber sorbent for the extraction of bisphenol A in a water sample

Novel molecularly imprinted polymer nanofibers (MIP‐NFs) were prepared for the adsorption of bisphenol A (BPA) in a water sample using the sol–gel process and the electrospinning technique. The effects of a number of synthesis parameters on the adsorption efficiency were investigated. The successful removal of BPA from MIP‐NFs was studied using UV–visible spectroscopy. The prepared MIP‐NFs were characterized by Fourier transform infrared, field emission SEM, TEM and energy dispersive X‐ray analysis. The results showed that the required molar ratio of 3‐aminopropyltriethoxysilane (APTES) to BPA was 15:1, which indicates a good performance in the rebinding test. Likewise, the molar ratio of APTES:acid:water was 1:2:9. The nylon 6 polymer solution, with a concentration of 12 wt%, showed a maximum adsorption capacity for BPA due to a decrease in the nanofiber diameter and an increase in the accessible sites. Furthermore, the maximum adsorption capacity of BPA was achieved at pH 7. Concerning the binding of BPA on MIP‐NFs, the experimental data matched well with the pseudo‐second‐order kinetics data and the Sips isotherm model. The saturated binding capacity for MIP‐NFs was predicted to be 115.1 mg g^?1, which was more than twice as high as that for non‐imprinted polymer nanofibers (46.82 mg g^?1). The results obtained in this study confirmed that the prepared MIP‐NFs showed considerable binding specificity for BPA in comparison with similar structural compounds such as phenol, naphthol and Naphthol AS, in aqueous solution. The binding capacity of MIP‐NFs remained almost constant after five cycles of reuse. The real sample analysis indicated that MIP‐NFs could be utilized as a useful sorbent material for the extraction of BPA from a water sample.