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#34524277   2021/09/15 To Up

Fcc hcp competition in colloidal hard-sphere nucleation: on their relative stability, interfacial free energy and nucleation rate.

Hard-sphere crystallization has been widely investigated over the last six decades by means of colloidal suspensions and numerical methods. However, some aspects of its nucleation behaviour are still under debate. Here, we provide a detailed computational characterisation of the polymorphic nucleation competition between the face-centered cubic (fcc) and the hexagonal-close packed (hcp) hard-sphere crystal phases. By means of several state-of-the-art simulation techniques, we evaluate the melting pressure, chemical potential difference, interfacial free energy and nucleation rate of these two polymorphs, as well as of a random stacking mixture of both crystals. Our results highlight that, despite the fact that both polymorphs have very similar stability, the interfacial free energy of the hcp phase could be marginally higher than that of the fcc solid, which in consequence, mildly decreases its propensity to nucleate from the liquid compared to the fcc phase. Moreover, we analyse the abundance of each polymorph in grown crystals from different types of inserted nuclei: fcc, hcp and stacking disordered fcc/hcp seeds, as well as from those spontaneously emerged from brute force simulations. We find that post-critical crystals fundamentally grow maintaining the polymorphic structure of the critical nucleus, at least until moderately large sizes, since the only crystallographic orientation that allows stacking close-packed disorder is the fcc (111) plane, or equivalently the hcp (0001) one. Taken together, our results contribute with one more piece to the intricate puzzle of colloidal hard-sphere crystallization.
Ignacio Sanchez-Burgos, Eduardo Sanz, Carlos Vega, Jorge R Espinosa

1453 related Products with: Fcc hcp competition in colloidal hard-sphere nucleation: on their relative stability, interfacial free energy and nucleation rate.

1 ml1 set250 100 UG1 ml1 mg96 tests1 ml5 ml100ug1 mg5ug

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#34523783   2021/09/15 To Up

Discovery, biocatalytic exploration and structural analysis of a 4-ethylphenol oxidase from Gulosibacter chungangensis.

The vanillyl-alcohol oxidase (VAO) family is a rich source of biocatalysts for the oxidative bioconversion of phenolic compounds. Through genome mining and sequence comparisons, we found that several family members lack a generally conserved catalytic aspartate. This finding led us to study a VAO-homolog featuring a glutamate residue in place of the common aspartate. This 4-ethylphenol oxidase from Gulosibacter chungangensis (Gc4EO) shares 42% sequence identity with VAO, contains the same 8α-N3-histidyl-bound FAD and uses oxygen as electron acceptor. However, Gc4EO features a distinct substrate scope and product specificity as it is primarily effective in the dehydrogenation of para -substituted phenols with little generation of hydroxylated products. The three-dimensional structure shows that the characteristic glutamate side chain creates a closely packed environment that may limit water accessibility and thereby protect from hydroxylation. With its high thermal stability, well defined structural properties and high expression yields, Gc4EO may become a catalyst of choice for the specific dehydrogenation of phenolic compounds bearing small substituents.
Alvigini Laura, Alejandro Gran-Scheuch, Yiming Guo, Milos Trajkovic, Mohammad Saifuddin, Marco W Fraaije, Andrea Mattevi

2483 related Products with: Discovery, biocatalytic exploration and structural analysis of a 4-ethylphenol oxidase from Gulosibacter chungangensis.

1 module1 module25 mg 15 ml 100ug1 module10 mg2 ml100ul1 module500 mg

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#34522930   2021/09/15 To Up

Cationic polythiophene-anionic fullerene pair in water and water-dioxane: studies on hydrogen bonding capabilities, kinetic and thermodynamic properties.

Despite the vast array of solution- and solid-state bio-analytical, bioelectronic and optoelectronic applications of cationic polythiophenes (CPTs), the number of studies focused on the role of hydrogen bonding (H-bonding) between these and other molecules is scarce, regardless of whether H-bonding is expected to play an important role in several such applications. Also, despite the advantages of using cosolvents to systematically examine the molecular interactions, there are no such studies for CPTs to our knowledge. This work presents a steady-state UV-vis/fluorescence spectroscopic, kinetic and thermodynamic study on the H-bonding interactions between a water-soluble, cationic-anionic (isothiouronium-tetraphosphonate), polythiophene-fullerene donor-acceptor pair with two-point, charge-assisted H-bonding (CAHB) capabilities, tuned using water or a 1,4-dioxane-water mixture (W-DI). Both solvents generate photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), spontaneous binding, H-bonding, ground-state complexing multiple site binding, formation of micelle-like aggregates and equivalence points at a similar concentration of the quencher. However, in comparison with water, W-DI promotes less-ordered, less packed micellar aggregates, due to hydrophobic desolvation of the H-bond and larger solvent displacement during the PT1-4Fo complexation. This would decrease the extent of charge-transfer and the size of the sphere-of-quenching, mainly by displacements or rotations of the H-bonds, instead of elongations, together with a possible larger extent of diffusion-controlled static quenching. At [4Fo] larger than the equivalence point the micelles formed in water do not have available binding sites due to a tighter aggregation, causing a decrease in the quenching efficiency, while the micelles formed in W-DI start showing larger quenching efficiencies, possibly due to an increase in entropy that overcomes the desolvation of the H-bonding. These results could be useful when analyzing outputs from systems including CPTs with H-bonding capabilities, operating in (or casted from) solvents with clear differences in polarity and/or H-bonding capacity.
Sergio E Domínguez, Benjamin Kohn, Timo Ääritalo, Pia Damlin, Ulrich Scheler, Carita Kvarnström

1756 related Products with: Cationic polythiophene-anionic fullerene pair in water and water-dioxane: studies on hydrogen bonding capabilities, kinetic and thermodynamic properties.

50μl200ulBox of 20 tubes1 Set1 Set1 Set1 Set2.50 nmol1 Set1 Set1 Set

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#34522917   2021/09/15 To Up

Tracking the emergence of epitaxial metal-oxide interfaces from precursor alloys.

Heterointerfaces with an epitaxial relationship, self-assembled nanocomposites of Pt(111)/CeO(111) 60°, were successfully formed by simple oxidation of PtCe alloy. Oxygen dissolution into the alloy causes spacial periodic compositional perturbation by atomic segregation, specifically, by local diffusion of Pt and Ce atoms. A striped pattern of Pt and CeO with a 4-5 nm periodicity formed through phase transformation of the Pt-rich alloy and oxidation of the Ce-rich alloy, respectively. Notably, a fully epitaxial relationship between the Pt and CeO phases was observed even in the initial stage. With continued annealing, the crystals rotated into an energetically favorable orientation with respect to the remaining (111)Pt//(111)CeO. The alloy oxidation and its resulting nanoscale phase-separation behavior were verified in an annealing experiment of an alloy specimen, which had been first thinned by a focused ion beam. Changing the oxygen partial pressure to the reaction interface may alter the orientation relationship between the hexagonal close-packed PtCe structure and face-centered cubic Pt/CeO structure, thereby altering the growth direction of the separated phases. These findings present a pathway for the self-assembly of epitaxial Pt(111)/CeO(111) interface and are expected to assist the structural design of metal-oxide nanocomposites.
Yu Wen, Hideki Abe, Kazutaka Mitsuishi, Ayako Hashimoto

1021 related Products with: Tracking the emergence of epitaxial metal-oxide interfaces from precursor alloys.

25 mg100ul1 mg 5 G2.5 mg50 ug 100ul 5 G100ug1 kit100μg

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#34521915   2021/09/14 To Up

Effect of disconnection of deformable units on the mobility and stiffness of 3D prismatic modular origami structures using angular kinematics.

Architected modular origami structures show potential for future robotic matter owing to their reconfigurability with multiple mobilities. Similar to modular robots, the units of modular origami structures do not need to be assembled in a fully packed fashion; in fact, disconnection can provide more freedom for the design of mobility and functionality. Despite the potential of expanded design freedom, the effect of the disconnection of units on the mobility and physical properties has not yet been explored in modular origami structures. Determining the mobility and weak spots of modular origami structures is significant to enable transformation with minimum energy. Herein, we investigate the effect of the disconnection of units on the mobility and stiffness of architected modular origami structures with deformable units using angular kinematics of geometry and topology of units and closed loops. Angular kinematics provides a valuable tool for investigating the complex mobility of architected modular origami structures with the disconnection of loops. The mobility of the network structure is a function not only of the number of disconnections but also of the topology of the loop. In contrast to the conventional negative perception of defects or disconnection in these materials, the disconnection can potentially be used to expand the design space of mobility for future robotic matter. Our findings can be used to develop powerful design guidelines for topologically reconfigurable structures for soft modular robots, active architected materials, implanted modular devices, deployable structures, thermal metamaterials, and active acoustic metamaterials.
Kai Xiao, Xiang Zhou, Jaehyung Ju

1463 related Products with: Effect of disconnection of deformable units on the mobility and stiffness of 3D prismatic modular origami structures using angular kinematics.

5 G500 Units500 Units500 Units200 units500 Units200 units100 units2000 Units10 mg5000 Units1

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#34519488   2021/09/14 To Up

A New Hexagonal Cobalt Nanosheet Catalyst for Selective CO Conversion to Ethanal.

We report a new form of catalyst based on ferromagnetic hexagonal-close-packed (hcp) Co nanosheets (NSs) for selective CORR to ethanal, CHCHO. In all reduction potentials tested from -0.2 to -1.0 V (vs RHE) in 0.5 M KHCO solution, the reduction yields ethanal as a major product and ethanol/methanol as minor products. At -0.4 V, the Faradaic efficiency (FE) for ethanal reaches 60% with current densities of 5.1 mA cm and mass activity of 3.4 A g (total FE for ethanal/ethanol/methanol is 82%). Density functional theory (DFT) calculations suggest that this high CORR selectivity to ethanal on the hcp Co surface is attributed to the unique intralayer electron transfer, which not only promotes [OC-CO]* coupling but also suppresses the complete hydrogenation of the coupling intermediates to ethylene, leading to highly selective formation of CHCHO.
Jie Yin, Zhouyang Yin, Jing Jin, Mingzi Sun, Bolong Huang, Honghong Lin, Zhenhui Ma, Michelle Muzzio, Mengqi Shen, Chao Yu, Hong Zhang, Yong Peng, Pinxian Xi, Chun-Hua Yan, Shouheng Sun

2611 related Products with: A New Hexagonal Cobalt Nanosheet Catalyst for Selective CO Conversion to Ethanal.

100Tests20 ug1 ml10 10ìg

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#34519411   2021/09/14 To Up

High-throughput discovery of a rhombohedral twelve-connected zirconium-based metal-organic framework with ordered terephthalate and fumarate linkers.

We report a metal-organic framework where an ordered array of two linkers with differing length and geometry connect [Zr 6 (OH) 4 O 4 ] 12+ clusters into a twelve-connected fcu net that is rhombohedrally distorted from cubic symmetry. The ordered binding of equal numbers of terephthalate and fumarate ditopic carboxylate linkers at the trigonal antiprismatic Zr 6 core creates close-packed layers of fumarate-connected clusters that are connected along the single remaining threefold axis by terephthalates. This well-defined linker arrangement retains the three-dimensional porosity of the Zr cluster-based UiO family while creating two distinct windows within the channels that define two distinct guest diffusion paths. The ordered material is accessed by a restricted combination of composition and process parameters that were identified by high-throughput synthesis.
Adam M Tollitt, Rebecca Vismara, Luke M Daniels, Dmytro Antypov, Michael W Gaultois, Alexandros P Katsoulidis, Matthew J Rosseinsky

2999 related Products with: High-throughput discovery of a rhombohedral twelve-connected zirconium-based metal-organic framework with ordered terephthalate and fumarate linkers.

5 mg 25 MG100tests100ug100ug2.5 mg25 mg100ug Lyophilized

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#34517702   2021/09/14 To Up

Artificial Chameleon Skin with Super-Sensitive Thermal and Mechanochromic Response.

Both the nonclose-packed structure and the large refractive index contrast of guanine nanocrystals and cytosols in iridophores play a vital role in the dynamic camouflage of chameleons, including the bright skin color and color tuning sensitivity to external stimulus. Here, the nonclose-packed photonic crystals consisting of ZnS nanospheres and polymers, which have similar refractive indices with guanine nanocrystals and cytosols, respectively, are constructed by a two-step filling strategy. [email protected] nanospheres are self-assembled to build intermediate close-packed photonic crystals followed by filling polymers in their interstices. The nonclose-packed photonic crystal is successfully achieved when the silica portion is etched by HF solution and refilled by polymers. Excitingly, the stimulus response of the designed photonic crystal is as sensitive as the skin of chameleons due to the similar contrast of refractive indices and nonclose-packed structure. The reflection peak of the structure can blue-shift more than 200 nm as the temperature increases from 30 to 55 °C or under 20% compressional strain. This work not only builds the nonclose-packed photonic crystals by introducing a two-step filling strategy but also proves that high refractive contrast in photonic crystals is an effective strategy to achieve ultrasensitivity, which is highly desirable for various applications.
Yue Wu, Yu Wang, Shufen Zhang, Suli Wu

2215 related Products with: Artificial Chameleon Skin with Super-Sensitive Thermal and Mechanochromic Response.

5mg25 mg96 tests 125 ml 2.5 mg100ug100.00 ul100ug500 MG

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