Modulated Self-Assembly of an Interpenetrated MIL-53 Sc Metal-Organic Framework with Excellent Volumetric H2 Storage and Working Capacity

To achieve optimal performance in gas storage and delivery applications, metal-organic frameworks (MOFs) must combine high gravimetric and volumetric capacities. One potential route to balancing high pore volume with suitable crystal density is interpenetration, where identical nets sit within the void space of one another. Herein, we report an interpenetrated MIL-53 topology MOF, named GUF-1, where one-dimensional Sc(µ2-OH) chains are connected by 4,4’-(ethyne-1,2-diyl)dibenzoate linkers into a material that is an unusual example of an interpenetrated MOF with a rod-like secondary building unit. A combination of modulated self-assembly and grand canonical Monte Carlo simulations are used to optimise the porosity of GUF-1; H2 adsorption isotherms reveal a very high Qst for H2 of 7.6 kJ mol-1 and a working capacity of 41 g L-1 in a temperature-pressure swing system, which is comparable to benchmark MOFs. These results show that interpenetration is a viable route to high performance gas storage materials comprised of relatively simple building blocks.

Molecular modelling approaches predicted 1,2,3-triazolyl ester of ketorolac (15K) to be a novel allosteric modulator of the oncogenic kinase PAK1

P21-activated kinases (PAKs) are serine/threonine protein kinase which have six different isoforms (PAK1–6). Of those, PAK1 is overexpressed in many cancers and considered to be a major chemotherapeutic target. Most of the developed PAK1 inhibitor drugs work as pan-PAK inhibitors and show undesirable toxicity due to having untargeted kinase inhibition activities. Selective PAK1 inhibitors are therefore highly desired and oncogenic drug hunters are trying to develop allosteric PAK1 inhibitors. We previously synthesized 1,2,3-triazolyl ester of ketorolac (15K) through click chemistry technique, which exhibits significant anti-cancer effects via inhibiting PAK1. Based on the selective anticancer effects of 15K against PAK1-dependent cancer cells, we hypothesize that it may act as an allosteric PAK1 inhibitor. In this study, computational analysis was done with 15K to explore its quantum chemical and thermodynamic properties, molecular interactions and binding stability with PAK1, physicochemical properties, ADMET, bioactivities, and druglikeness features. Molecular docking analysis demonstrates 15K as a potent allosteric ligand that strongly binds to a novel allosteric site of PAK1 (binding energy ranges – 8.6 to – 9.2 kcal/mol) and does not target other PAK isoforms; even 15K shows better interactions than another synthesized PAK1 inhibitor. Molecular dynamics simulation clearly supports the stable binding properties of 15K with PAK1 crystal. Density functional theory-based calculations reveal that it can be an active drug with high softness and moderate polarity, and ADMET predictions categorize it as a non-toxic drug as evidenced by in vitro studies with brine shrimp and fibroblast cells. Structure–activity relationship clarifies the role of ester bond and triazol moiety of 15K in establishing novel allosteric interactions. Our results summarize that 15K selectively inhibits PAK1 as an allosteric inhibitor and in turn shows anticancer effects without toxicity.

Glasses denser than the supercooled liquid

When aged below the glass transition temperature, Tg, the density of a glass cannot exceed that of the metastable supercooled liquid (SCL) state, unless crystals are nucleated. The only exception is when another polyamorphic SCL state exists, with a density higher than that of the ordinary SCL. Experimentally, such polyamorphic states and their corresponding liquid–liquid phase transitions have only been observed in network-forming systems or those with polymorphic crystalline states. In otherwise simple liquids, such phase transitions have not been observed, either in aged or vapor-deposited stable glasses, even near the Kauzmann temperature. Here, we report that the density of thin vapor-deposited films of N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) can exceed their corresponding SCL density by as much as 3.5% and can even exceed the crystal density under certain deposition conditions. We identify a previously unidentified high-density supercooled liquid (HD-SCL) phase with a liquid–liquid phase transition temperature (TLL) ∼35 K below the nominal glass transition temperature of the ordinary SCL. The HD-SCL state is observed in glasses deposited in the thickness range of 25 to 55 nm, where thin films of the ordinary SCL have exceptionally enhanced surface mobility with large mobility gradients. The enhanced mobility enables vapor-deposited thin films to overcome kinetic barriers for relaxation and access the HD-SCL state. The HD-SCL state is only thermodynamically favored in thin films and transforms rapidly to the ordinary SCL when the vapor deposition is continued to form films with thicknesses more than 60 nm.

Numerical Simulation of the Effect of Wall-Equiaxed Crystal Density on the Number of Columnar Crystals and the Thickness of an Equiaxed Crystal Layer for Al-4.7%Cu Alloy Ingot Based on 3D LBM-CA Method

In this paper, the lattice Boltzmann–cellular automata (LBM-CA) model with dynamic and static grids was used to study the growth of three-dimensional (3D) multidendrites under directional solidification with random preferred angles. In the static grid, the temperature field, flow field, and solute field during solidification were calculated by the LBM method, and in the dynamic grid, each dendrite evolution was calculated based on the CA method at its preferential crystallographic orientation. The coupling of LBM and CA was made by interpolation of the correlation quantities between the two sets of grids. The effects of wall-equiaxed crystal density on the number of columnar crystals and the thickness of the equiaxed crystal layer were studied by this model. The results showed that the density of the wall-equiaxed crystal has little effect on the number of columnar crystals and the thickness of the equiaxed crystal layer. When other conditions were the same, the lower the undercooling, the fewer the columnar crystals, and the thicker the equiaxed layer. In addition, the smaller the heat transfer coefficient, the lower the number of columnar grains, and the smaller the thickness of equiaxed grains.

Crystal structure or chemical composition of salt–sugar-based metal–organic frameworks: what are the nonlinear optical properties due to?

In the last few decades optical imaging techniques based on nonlinear optical properties have been of interest for biosensing applications. This work focuses on two isostructural and isomorphous sugar-derived metal–organic frameworks (MOFs) with second-harmonic generation (SHG) properties, in order to investigate their possible application as biosensors in view of their high biocompatibility. Combining 2-deoxy-D-galactose with the metal halogenides CaX 2 (X = Br, I), two new isomorphous MOFs of formula [Ca(C6H12O5)2]X 2 were obtained and characterized through single-crystal X-ray diffraction. The first-order static hyperpolarizability and second-order susceptibility were estimated by in vacuo and in-crystal density functional theory calculations, and compared with the experimental SHG response of powdered samples. The parameters influencing the SHG response of these compounds were investigated by comparison with similar previously analysed MOFs, to understand how to design more efficient materials to be used as nanoprobes by exploiting crystal engineering techniques.

Development of a combined XRF/XPS surface-analysis system for the surface-layer quantification of 28Si spheres

<p class="Abstract">To achieve a new kilogram definition using the X-ray crystal density method, the Center for Measurement Standards, Industrial Technology Research Institute in Taiwan has established the combined XRF (X-ray fluorescence)/XPS (X-ray photoelectron spectroscopy) surface analysis system for the quantitative surface-layer analysis of Si spheres. The surface layer of a Si sphere is composed primarily of an oxide layer, carbonaceous contamination and physisorbed/chemisorbed water. This newly combined instrument has been implemented to measure the XRF for the direct determination of the mass deposition of oxygen (ng/cm²) with a calibrated silicon drift detector and the XPS for the ratio between the elements (O, Si, C) and composition identification. These two complementary methods of X-ray metrology allow an accurate determination of the surface-layer mass of the Si sphere. In this paper, the construction of a combined XRF/XPS surface-analysis system is reported, including the surface characterisation method, the assembly of parts of the load-lock chamber and ultra-high-vacuum analysis chamber, the vacuum-system design, hardware integration and the intended research on surface-layer measurement. It is anticipated that the measured surface-layer mass will be combined with the core mass of the Si sphere.</p>

Evaluation of Phyllanthus niruri L. from Malaysia for In-vitro Anti-Urolithiatic Properties by Different Solvent Extraction

The Phyllanthus niruri is traditionally used for curing of kidney disorders and urinary stones in Malaysia. Hence the current work was aimed to evaluate the effect of different solvents extract (n- hexane, ethyl acetate, methanol and water) of P. niruri for in vitro anti-urolithiatic properties in terms of inhibition activity on CaOx by using the rate of CaOx aggregation assay and dissolution of calcium oxalate (CaOx) crystal by using titrimetry method. Cystone was used as positive control. The effects of cystone on slope of nucleation and aggregation as well as growth of CaOx were evaluated spectrophotometrically. The highest yield percentage of P.niruri was occupied by methanol (5.74 %). The maximum inhibition against aggregation of CaOx crystals was also occupied by methanol (66.67 % ± 1.61) and was comprised with alkaloid, steroid, terpenoid and tannin. Dissolution effect on calcium oxalate crystals indicates that the aqueous extracts of P. niruri was found to be more effective in dissolution of CaOx with 63.33 % ± 1.44. P. niruri significantly (P < 0.05) inhibited the slope of nucleation and aggregation of CaOx crystallization, and reduced the crystal density. The results of the present study confirmed that P. niruri leaves can be used as remedial mediator for urolithiasis. However, further studies are required for isolation and identification of active constituents and their in-vivo confirmation.