Diffusion Of Molecules Research Articles

Highly Selective Ethylene/Ethane Separation in MOF Composites through Pore Contraction and Particle Size Enlargement Strategy.

The discrimination of ethylene (C2H4) and ethane (C2H6) by the precise regulation of porous materials is important and challenging. In this work, the quasi-exclusion of C2H6 from C2H4 is realized through a facile polymer modification and shaping method of metal-organic framework ZnAtzPO4 (Atz = 3-amino-1,2,4-triazole). The polymer (carboxymethyl cellulose, CMC) modification and shaping of ZnAtzPO4@CMC result in pore contraction and particle size enlargement, which impedes the diffusion of larger C2H6 molecules and improves the kinetic separation of C2H4/C2H6. The C2H6 capacity decreases steeply from 1.63 (ZnAtzPO4 powder) to 0.27 mmolg-1 (ZnAtzPO4@CMC), and the resulting C2H4/C2H6 uptake ratio increases from 1.38 to 6.67. Kinetic adsorption experiments confirm that ZnAtzPO4@CMC presents a negligible C2H6 dynamic capacity and the diffusion difference between C2H4 and C2H6 is amplified significantly. The corresponding kinetic C2H4/C2H6 separation selectivity of ZnAtzPO4@CMC increases from 13.06 (ZnAtzPO4) to 34.67, superior to the most reported benchmark materials. Furthermore, ZnAtzPO4@CMC exhibits excellent breakthrough performance for equimolar C2H4/C2H6 mixture separation. This study provides guidance to discriminate similar gases through polymer modification of MOFs.

Efficient synthesis of nanosized zeolite Y utilizing gradual heating: post-synthesis modification and their catalytic performance in propylene oligomerization

Abstract Producing nanosized zeolites Y has been restricted to a Si/Al ratio lower than 2.0, requiring prolonged crystallization periods. This study employed temperature ramps during nucleation and crystallization to synthesize nanosized zeolites Y with a Si/Al ratio of 2.4, ranging from 47 to 100 nm, in just one day. Sequential post-synthesis desilication and dealumination treatments were used to modify the pore structure and acidity of the zeolites, leading to hierarchical zeolite formation. These modifications enhanced the structural stability and porosity of the zeolites while preserving their high crystallinity. Desilicated zeolites, unlike dealuminated ones, possessed straighter and more uniform mesoporous within their crystals, with diameters smaller than 5 nm. Additionally, successive desilication produced a greater number of intracrystalline mesoporous. The solids obtained from both processes exhibited porosity within the zeolite structure connected to the external surface, potentially improving the mass transfer limitations of the original zeolite due to the lack of mesoporous. Catalysts were prepared using modified nanozeolites for evaluation in the propylene oligomerization reaction. Catalysts based on dealuminated and desilicated nanosized zeolite Y showed high conversions above 20%, especially for dealuminated zeolites with conversions of 50%. Additionally, the catalysts demonstrated selectivity towards hydrocarbons in the C5-C7 range, suggesting better diffusion and access of propylene molecules to the active sites, favoring the formation of medium-sized hydrocarbon fractions. Conversely, the formation of longer hydrocarbon chains (C12+) was not favored, possibly due to insufficient mesoporous for larger molecule diffusion and a distribution of acid sites that encourages the union of longer hydrocarbon chains.

The Value of DTI in Differential Diagnosis of Embryonal Tumors Occurring in the Brainstem and Brainstem Gliomas in Pediatric Patients

IntroductionThere are no apparent distinctions in clinical presentation or conventional imaging findings between brainstem gliomas and embryonal tumors occurring in the brainstem. Our aim was to study the role of diffusion tensor imaging in differentiating embryonal tumors from gliomas of the brainstem. Patients and methodsThree cases of embryonal tumors occurring in the brainstem and nineteen cases of brainstem gliomas were analyzed retrospectively. ResultThe most common brainstem gliomas are diffuse intrinsic pontine gliomas(DIPG). On the fiber tracking images, brainstem gliomas were associated with relatively intact projection fibers that continuously traversed the tumor and followed the trajectory of normal neural fibers, while embryonal tumors were associated with disruption of projection fibers. The close cellularity created tissues with significant directional properties in embryonal tumors, restricting the diffusion of water molecules. As a result, there were areas of high anisotropy within the embryonal tumors. Additionally, we observed that the apparent diffusion coefficient (ADC) value of embryonal tumors occurring in the brainstem was lower than that of brainstem gliomas, and the difference was statistically significant. (P < 0.05). ConclusionDisruption of projection fibrous within the tumor on diffusion tensor imaging may help differentiate embryonal pathology from glial.

Thumb-sized 3D-Printed cymbal microneedle array (CyMA) for enhanced transdermal drug delivery.

Transdermal drug delivery presents a compelling alternative to both needle injection and oral ingestion of medication, as it enhances patient adherence and convenience through its non-invasive and painless administration method. The use of microneedles penetrates the barrier of the stratum corneum, facilitating the sustained delivery of drugs across the skin. However, their efficacy has been limited by the slow diffusion of molecules and often requires external triggers. Herein, a lightweight and minimized 3D-printed microneedle array is introduced, employing a cymbal-type ultrasound transducer, as the external engine for deeper and faster transdermal drug delivery. A theoretical finite element model was developed and the optimization design was conducted for structural parameters. The optimized assembled prototype was fabricated using high-precision 3D printing and weighs only 20 g. In vivo experiments using a diabetic mouse model demonstrate that local insulin delivery with CyMA achieves systemic effects comparable to intraperitoneal administration. Such compact and effective microneedle delivery technology offers considerable promise therapeutic applications on the skin and intraoral use.

Design and Assembly of Continuous Macro‐Micro‐Porous Metal‐Organic Framework Film Assisted by Atomic Layer Deposition for Biosensing

AbstractConstructing highly oriented and ordered macro‐pores on metal‐organic framework (MOF) film can surpass the inherent limitations from micro‐pores, promote multiphase adsorption, and expedite electrochemical reaction, but the fabrication remains extremely challenging. Here, continuous macro‐micro‐porous MOF films are achieved by combining polystyrene microsphere template and induction effect of ZnO nanomembrane prepared by atomic layer deposition. In addition to the intrinsic micro‐pores, the fabricated MOF film exhibits oriented and ordered macro‐porous structures. Compared with the macro‐porous MOF particles and conventional MOF film, the mass diffusion and charge transportation in the macro‐micro‐porous MOF film are significantly improved, endowing the film with excellent electrochemical activity. The sensor device made from macro‐micro‐porous ZIF‐67 film toward glucose exhibits excellent performance, e.g., high sensitivity, low limit of detection, and fast response, due to rapid glucose molecule diffusion and enhanced exposure of active sites via interconnected macro‐porous channels. This work paves the way for the application of MOF film in high‐performance biosensor chip and therefore may have great potential in post‐Moore period.

Intraspecific gene regulation in cis- and trans.

Changes in gene expression underlie much of evolution and occur via either cis-acting mutations, which lie near the affected gene and act in a context specific manner, or trans-acting mutations, which may be far from the affected gene and act through diffusible molecules such as transcription factors. A commonly held view is that most expression variation within species is controlled in trans- while expression differences between species are largely controlled in cis-. Here, we summarize recent intraspecific gene regulation studies and find, contrary to this widely held view, that many studies in diverse taxa have revealed a large role for cis-acting mutations underlying expression variation within species. A review of the existing literature also shows that preparations using whole organisms rather than individual tissues may be biased towards identifying trans-regulation. Moreover, we note several examples of predominantly cis-acting regulation in recently diverged populations adapted to different environments. We highlight the challenges of drawing general conclusions from comparisons among studies that use different methodologies and we offer suggestions for studies that will address outstanding questions concerning the evolution of gene regulation.

Molecular Dynamics Study of Carbon Dioxide Gas Within Ice XVII Structure

We conducted a molecular dynamics study on CO2 hydrate within the ice XVII structure to examine the molecular diffusion of CO2 molecules, as it is essential to the hydrate potential as a carbon capture. The simulated CO2 hydrate system used 324 water molecules and 90 CO2 molecules. We used the TIP4P/Ice model for water molecules, and the CO2 molecules were treated as united atom. The simulations were carried out at 273,15 K under various pressures of 200 MPa, 500 MPa, and 1000 MPa for 1,50 ns, with a step size of 1 fs. The results showed that the CO2 molecules were confined and freely moved inside the cage-like chiral tube along the c-axis of the ice XVII structure. No significant inter-cage hopping was observed during the evolution of all simulated systems. The diffusion coefficient values for CO2 molecules within the ice XVII structure were 5.03 × 10-8 cm2s-1, 2.45 × 10-8 cm2s-1, and 8.86 × 10-8 cm2s-1 for the respective pressure variations of 200 MPa, 500 MPa, and 1000 MPa, resulting in an inverse proportional with the system's pressure. A higher diffusion coefficient facilitates a faster the mass transfer and adsorption rate of CO2 in formation build up of the CO2 hydrate system.

Efficient CO2 Capture Using Nitrogen-Enriched Microporous Carbon Derived from Polybenzoxazine in a Single-Step Process for Environmental Sustainability

In this research, we successfully synthesized nitrogen-enriched microporous carbon through a meticulous process involving two different activation procedures. Initially, polybenzoxazine was carbonized at 800 °C to create a precursor material, which was then activated with two different activating agents (KOH and KMnO4) at the same temperature. This activation significantly enhanced the material’s porosity, increasing its specific surface area from 335 m2/g (KOH activated) to 943 m2/g (KMnO4 activated). XPS analysis confirmed the presence of nitrogen functionalities, including secondary-N, oxide-N, pyridone-N, and pyridine-N, which are critical for CO2 adsorption. Adsorption tests demonstrated a high CO2 uptake of 3.8 mmol/g at 25 °C and 1 bar, driven by a combination of physisorption (physical interaction with the surface area) and chemisorption (chemical interaction with nitrogen sites). This high adsorption capacity can be attributed to the carbon’s substantial surface area, significant micropore volume, and the interconnected network of pores, which together provide structural stability and facilitate the diffusion of CO2 molecules. These findings suggest that this nitrogen-enriched microporous carbon, derived from polybenzoxazine, holds significant promise as a highly efficient material for applications in CO2 capture and storage.

Solvothermal Template-Induced Hierarchical Porosity in Covalent Organic Frameworks: A Pathway to Enhanced Diffusivity.

The rapid advancement of covalent organic frameworks (COFs) in recent years has firmly established them as a new class of molecularly precise and highly tuneable porous materials. However, compared to other porous materials, such as zeolites and metal-organic frameworks, the successful integration of hierarchical porosity into COFs remains largely unexplored. The challenge lies in identifying appropriate synthetic methods to introduce secondary pores without compromising the intrinsic structural porosity of COFs. In this study, a template-induced synthetic methodology is realized to facilitate the construction of hierarchically porous COFs (hCOFs). This novel approach utilizes commercially available zinc oxide nanoparticles as a hard template, enabling to increase the total pore volume of a series of β-ketoenamine-linked COFs as well as an imine-based COF while preserving their surface areas. In addition to transmission electron microscopy and gas adsorption analyses, small-angle X-ray scattering and pulsed field gradient nuclear magnetic resonance techniques are employed to investigate the hierarchical porosity and diffusivity of guest molecules within hCOFs. This study demonstrates that the hierarchically porous nature of hCOFs significantly reduces diffusion limitations, thus leading to simultaneous enhancements in adsorption capacity, diffusivity, and catalytic performance.

On-Chip Stimulated Raman Scattering Imaging and Quantification of Molecular Diffusion in Aqueous Microfluidics.

Numerous chemical reactions and most life processes occur in aqueous solutions, where the physical diffusion of small molecules plays a vital role, including solvent water molecules, solute biomolecules, and ions. Conventional methods of measuring diffusion coefficients are often limited by technical complexity, large sample consumption, or significant time cost. Here, we present an optical imaging method to study molecular diffusion by combining stimulated Raman scattering (SRS) microscopy with microfluidics: a "Y"-shaped microfluidic channel forming two laminar flows with a stable concentration gradient across the interface. SRS imaging of a specific molecule allows us to obtain a high-resolution chemical profile of the diffusion region at varying inspection locations and flow rates, which enables the extraction of diffusion coefficients using the convection-diffusion model. As a proof of concept, we measured diffusion coefficients of molecules including water, protein, and multiple ions, with a sample volume of less than 1 mL and a time cost of less than 10 min. Moreover, we demonstrated a high-resolution three-dimensional (3D) reconstruction of the diffusion patterns in the microfluidic channel. The high-speed microfluidic SRS platform holds the potential for quantitative measurements of molecular diffusion, chemical reaction, and fluidic dynamics at the liquid-liquid interfaces.

Long-lived cytokinetic bridges coordinate sister-cell elimination in mouse embryos.

Apoptosis is a key feature of preimplantation development, but whether it occurs in a cell-autonomous or coordinated manner was unknown. Here, we report that plasma membrane abscission, the final step of cell division, is profoundly delayed in early mouse embryos such that a cytokinetic bridge is maintained for the vast majority of the following interphase. Early embryos thus consist of many pairs of sister cells connected by stable cytokinetic bridges that allow them to share diffusible molecules. We show that apoptotic regulators are shared through cytokinetic bridges and that these bridges ensure that if one cell enters apoptosis, its sister cell does as well. Long-lived cytokinetic bridges are thus a previously unappreciated form of cell-cell communication within the mouse embryo that coordinate the clearance of pairs of cells with similar developmental histories.

Study on the diffusion model of two dimensional T type planar network

In this paper, we proposed a memory diffusion model of molecules on T-type planar network. This model regards the diffusion of molecules in zeolite as a jump from one adsorption site to another adjacent adsorption site. The probability of the jump is a composite probability, which includes both the probability provided by the transition state theory and the information from which direction the target molecule comes. This method gives an expression for the influence of the memory effect on the anisotropy of molecular diffusion under different conditions, revealing that the diffusion coefficients along the two crystal axes on the zeolite are related. Taking AWO zeolite as an example, the diffusion anisotropy of five simple molecules, CF4, Xe, CH4, N2, and Ar, in AWO zeolite was studied by molecular dynamics method. The main factors affecting the diffusion in zeolite were proposed, and the importance of memory effect in the molecular diffusion inside zeolite was verified.

Highly efficient and rapid removal of Congo red dye from textile wastewater using facile synthesized Mg/Ni/Al layered double hydroxide

Layered double hydroxides (LDH) are compounds with unique structures of hydroxide functional groups on their surfaces, and they have the proper arrangement of divalent and trivalent cations to adjust their unique catalytic actions. LDH was synthesized utilizing the co-precipitation technique and was thermally treated at 300 °C. The prepared compounds were chemically and structurally elucidated using FT-IR, XRD, SEM, BET, TG-DTA, and XPS characterization. We found that the thermal treatment of the prepared magnesium/nickel-LDH resulted in dehydration and dehydroxylation in its chemical structure. The crystallinity, the surface area, and the pore volume of the formed meso- and micropores were improved considerably after the thermal treatment. The efficiency of the uptake process was increased from 84 to 97% after the thermal treatment process, and the adsorption process tracked the Freundlich adsorption isotherm and pseudo-second-order kinetic model. The kinetics indicated the occurrence of three stages, and the diffusion of dye molecules into the pores was the rate-determining step. Different real water sample treatments showed the applicability of the thermally treated Mg/Ni/Al-LDH in the treatment process under optimized conditions. The presented mechanism of the uptake process using the prepared compounds comprises several interactions between the dye molecules and the thermally treated Mg/Ni/Al-LDH. The study presented the new application for Mg/Ni/Al-LDH in the as-prepared and thermally treated forms to uptake Congo-red (CR) dye from textile effluents.

Challenges in the Characterization and Purification of (Peptide)n-Calix[4]Resorcinarene Conjugates Synthesized via Thiol-Maleimide Reaction Using Liquid Chromatography

The separation and purification of molecular compounds and their functionalized derivatives is a common challenge in organic synthesis. In particular, calix[4]resorcinarenes present a high potential for chemical derivatization at their upper edge by aminomethylation reactions, and these compounds and their derivatives require appropriate analytical methodologies for their analysis, separation, and purification. In this study, C-tetra(propyl)calix[4]resorcinarene was synthesized and functionalized with maleimide groups by optimized aminomethylation reactions, obtaining a mixture of mono-, di-, tri-, and tetrasubstituted compounds. Initial separation by RP-HPLC with a core-shell column showed poorly resolved peaks, indicating a loss of separation efficiency. Therefore, a monolithic C18 column was used, which significantly improved the separation, thanks to its larger pore volume and continuous structure facilitating the diffusion of these bulky molecules, notably improving efficiency. Finally, the six compounds functionalized with maleimide groups were efficiently separated and enriched by RP-SPE by analytical method transfer, and the two peptides of six and the thirteen residues derived from LfcinB (20–25): RRWQWR were synthesized by SPPS-Fmoc/tBu and purified. These were modularly linked by the Michael thiol-maleimide addition reaction obtaining six (peptide)n-resorcinarene conjugates. The analytical method by RP-HPLC with a monolithic C18 column, the separation and purification by RP-SPE were used transversally in all the steps to obtain compounds with adequate purities and quantities. Finally, the antibacterial activities of the six conjugates were evaluated against E. coli and E. faecalis strains, and it was determined that three aminomethylated compounds and one monosubstituted conjugate showed activity against E. faecalis. Our work established a new modular conjugation strategy between calix[4]resorcinarenes and peptides by thiol-maleimide click chemistry, and a methodology of separation, purification, and enrichment for these products by RP-HPLC and RP-SPE, which permitted us to obtain quantities with purities appropriate for their characterization by NMR, LC-MS and antibacterial activity assays.

Feasibility study for evaluating cervical intervertebral disc degeneration using axial diffusion tensor imaging.

Intervertebral disc (IVD) degeneration is the main cause of neck pain. Although conventional magnetic resonance imaging can detect morphological changes in intervertebral disc degeneration, it cannot provide accurate and objective evaluations. Magnetic resonance diffusion tensor imaging (DTI) reflects the microstructural changes in tissues by describing the diffusion of water molecules. It was initially applied to the evaluation of lumbar disc degeneration; however, no study has used DTI to evaluate cervical disc degeneration. To conduct a prospective study to evaluate the efficacy and feasibility of DTI in quantifying cervical disc degeneration by correlating the main parameters of axial DTI of intervertebral discs, namely fractional anisotropy (FA) and mean diffusivity (MD) values, using the Pfirrmann grade. The cervical discs of 30 symptomatic volunteers with neck pain and 20 asymptomatic volunteers were assessed using a 3.0 T magnetic resonance scanner. We evaluated intervertebral discs from C3/4 to C6/7 in each volunteer. The Pfirrmann grades, FA value, and MD value on the conventional magnetic resonance imaging were evaluated. The Kruskal-Wallis test and Wilcoxon rank-sum test were used to compare the FA and MD values of subjects with different degeneration levels. Statistical analysis showed that the FA value of the nucleus pulposus in patients group was significantly higher than that in the asymptomatic volunteers, and the MD value of the nucleus pulposus was significantly lower than that in the asymptomatic volunteers, and the difference was significant (P < 0.05). In the study group, with an increase in cervical intervertebral disc grade, the FA value of the nucleus pulposus also showed a gradual upward trend, and this difference was significant (P < 0.05). The MD value of the nucleus pulposus showed a gradual downward trend, except between grades I and II, which indicates that the axial FA value can better show the early pathological changes of the cervical intervertebral disc. The FA and MD values of the cervical intervertebral disc can quantitatively evaluate the degree of degeneration of the cervical intervertebral disc; axial DTI imaging technology can provide a good theoretical basis for the imaging diagnosis of cervical intervertebral disc degeneration and has important clinical application value.

DMSO-Assisted Control Enables Highly Efficient 2D/3D Hybrid Perovskite Solar Cells.

Building 2D/3D heterojunction is a promising approach to passivate surface defects and improve the stability of perovskite solar cells (PSCs). Developing effective methods to build high-quality 2D/3D heterojunction is in demand. The formation of 2D/3D heterojunction involves both the diffusion of 2D spacer molecules and phase transition from 3D to 2D structure. Herein, a DMSO-assisted method is demonstrated to simultaneously regulate both the 2D/3D formation kinetics, yielding high-quality 2D top layer with continuous coverage, which enhances the photovoltaic performance of PSCs. It is found that the presence of DMSO significantly facilitates the diffusion of 2D spacer cation. Meanwhile the residual DMSO may partially dissolve the surface perovskite, facilitating the reaction between 2D molecules with 3D perovskite and ultimately leading to sequential secondary crystal growth and the appearance of a distinct 2D layer. The formation of high-quality 2D layer effectively passivates the surface defects thus suppresses the interfacial charge recombination. As a result, the champion PSC based on optimal 2D/3D heterojunction exhibits a high fill factor of 85% and a power conversion efficiency of 24%. The work offers a novel perspective for the construction of 2D/3D perovskite heterojunctions.

Genipin-crosslinked double PLL membranes overcome the strength-diffusion trade-off in cell encapsulation without compromising biocompatibility.

Cell microencapsulation technologies allow non-autologous implantation of therapeutic cells for sustained drug delivery purposes. The perm-selective membrane of these systems provides resistance to rupture, stablishes the upper molecular weight limit in bidirectional diffusion of molecules, and affects biocompatibility. Thus, despite being a decisive factor to succeed in terms of biosafety and therapeutic efficacy, little progress has been made in its optimization so far. Here we show that, compared to other usually used coating designs, genipin-crosslinked double poly-L-lysine (GDP) membranes are able to simultaneously improve mechanical and mass-transport properties of the microcapsules, without causing any significant increase in the foreign body response when implanted in vivo. In particular, we show that GDP membranes confer capsular integrity under high pressures, both internal and external. Furthermore, this membrane design allows for more efficient bidirectional diffusion of molecules in the 20-40 kDa range while preserving the molecular weight cut-off required for exerting an effective immunobarrier. These findings may also be useful for optimizing the membrane characteristics of multiple drug delivery systems.

Interface Mechanism of Promoting Low-Rank Coal Flotation by Characteristic Groups in Hydrophilic Moieties of Cationic-Anionic Surfactants.

Flotation is an interfacial process involving gas, liquid, and solid phases, where polar ionic promoters significantly influence both gas-liquid and solid-liquid interfaces during low-rank coal (LRC) flotation. This study examines how the structures of hydrophilic groups in cation-anion mixed promoters affect the interfacial flotation performance of LRC pulp using flotation tests, surface tension tests, wetting heat tests, and molecular dynamics simulations. Results indicate that cation-anion mixed promoters enhance the LRC floatability to varying degrees. When the cationic hydrophilic head contains a benzyl group and the anionic head contains an ethoxy group, both the floatability and selectivity improve. These mixed promoters exhibit superior surface activity compared to single ionic solutions, particularly with ethoxy-containing anions, which demonstrate an increased density and viscoelasticity at the gas-liquid interface. The combination of a benzyl cation and an ethoxy anion results in dense adsorption at the solid-liquid interface, maximizing wettability differences between organic matter and mineral surfaces. This is attributed to hydrogen bonds and π-π interactions between the promoter and the coal surface, enhancing adsorption selectivity. Hydrophobic chains shield polar sites on the LRC surface, promoting water molecule diffusion and providing sites for nonpolar oil molecule adsorption, thereby improving LRC flotation performance.

Nanoscale self-assembly and water retention properties of silk fibroin-riboflavin hydrogel.

Silk-fibroin hydrogels have gained considerable attention in recent years for their versatile biomedical applications. The physical properties of a complex hydrogel, comprising silk fibroin and riboflavin, surpass those of the silk fibroin-hydrogel without additives. This study investigates silk fibroin-riboflavin (silk-RIB) hydrogel at the atomistic level to uncover molecular structures and chemical characteristics specific to silk fibroin and riboflavin molecules in an aqueous medium. The interplay between hydrophilic riboflavin and hydrophobic silk fibroin polymers facilitates the formation of solubilized silk fiber, which subsequently evolves into a nano-scale hydrogel over time. Eventually, the interlinked RIB stacks form a scaffold that not only accommodates silk fibroin aggregates but also encloses water pockets, preserving the moisture level and enhancing the thermal conductivity of the hydrogel. To explore water retention properties and the role of ions, two sets of simulations of semi-hydrated hydrogel in the presence and absence of ions are conducted. The presence of ions significantly influences the dynamics of RIB and silk fibroin. Favorable interactions with the ions impede the unrestricted diffusion of these larger molecules, potentially leading to a stable structure capable of retaining water for a prolonged duration. The complete removal of water results in further shrinkage of the anhydrous silk-RIB hydrogel or xerogel (XG), yet its porosity and structural integrity remain intact. These findings offer valuable insights into the behavior of silk fibroin hydrogel and XG, paving the way for materials engineering in aqueous environments to develop biomedical devices with customized functional properties.

Tailoring the surface islands to modulate the diffusion of guest molecules over the TS-1 zeolites for enhanced selectivity in the 1-hexene epoxidation

Tailoring the surface islands to modulate the diffusion of guest molecules over the TS-1 zeolites for enhanced selectivity in the 1-hexene epoxidation