Open Structure Research Articles

The Structure of Open and Distance English Language Teaching Models: A Follow Up Study 2018 – 2023

In recent years, the widespread adoption of Open and Distance Learning (ODL) has revolutionized education, especially English language teaching. ODL has democratized access to educational resources and enables interaction between students and instructors across geographical boundaries. Moreover, technology integration has emerged as a dominant theme, with a focus on web-based, computeraided, and mobile-learning systems. However, the study advocates for innovative approaches, such as mobile and game-based learning, aligning with contemporary trends. The adoption of various evaluation methods shows the recognition of individual differences and underscores the need for a comprehensive view of learner progress. This research employs a systematic approach to review literature and investigate the common structures of ODL models for teaching the English language, focusing on articles published between 2018 and 2023. This study categorizes studies based on five macro dimensions of ODL —management, communication, learning, technology, and evaluation—in order to identify common themes and patterns within the literature. In contrast to a previous study spanning 1990 to 2017, this investigation uncovers the evolving landscape of distance education, underscoring the need for continued research and improvement. This research emphasizes the lack of a comprehensive management model for EFL education delivered through ODL, and suggests the need for further investigation in this domain. Moreover, the findings emphasize the significance of leveraging diverse communication models to enhance learner engagement. A shift towards autonomous learning models is observed, demanding further investigation into strategies that support effective self-directed learning experiences. In conclusion, this comprehensive analysis provides a roadmap for advancing ODL models in English-language education. To enhance the quality and accessibility of English language instruction in ODL, educators and researchers can concentrate on addressing management gaps, optimizing communication strategies, promoting autonomous learning, exploring advanced technologies, and refining evaluation approaches. This research offers a rich repository of knowledge for educators, researchers, and academic institutions that wish to deepen their comprehension and practical application of ODL approaches in the domain of English language instruction

Effect of Different Hydrocolloids on the Qualitative Characteristics of Fermented Gluten-Free Quinoa Dough and Bread.

The aim of this research was to optimize the production process of fermented gluten-free quinoa bread. To this end, the effect of different hydrocolloids on the technological, fermentative, and nutritional properties of quinoa-based gluten-free doughs and breads was evaluated. For this purpose, 3% of four different hydrocolloids (sodium alginate, k-carrageenan, xanthan gum, and hydroxypropyl methylcellulose (HPMC)) were used in gluten-free doughs composed of 50% quinoa flour, 20% rice flour, and 30% potato starch. The rheological and fermentative properties of the doughs were evaluated, as well as the chemical composition, specific volume, crust and crumb color, and alveolar structure profile of gluten-free breads. The results highlighted the differences in dough rheology during mixing and fermentation of the doughs. In particular, HPMC showed a good gas retention (93%) during the fermentation of quinoa dough by registering the highest maximum dough development height (Hm). The gluten-free quinoa breads obtained were characterized by significantly different quality parameters (p < 0.05). The use of 3% HPMC resulted in breads with the lowest baking loss, the highest volume, and the most open crumb structure.

Spectroscopic Observations of the Solar Corona during the 2017 August 21 Total Solar Eclipse: Comparison of Spectral Line Widths and Doppler Shifts between Open and Closed Magnetic Structures

The spectroscopic observations presented here were acquired during the 2017 August 21 total solar eclipse (TSE) with a three-channel partially multiplexed imaging spectrometer operating at extremely high orders (>50). The 4 R ⊙ extent of the slit in the north–south direction scanned the corona starting from the central meridian out to approximately 1.0 R ⊙ off the east limb throughout totality. The line widths and Doppler shifts of the Fe x (637.4 nm) and Fe xiv (530.3 nm) emission lines, characteristic of 1.1 × 106 K and 1.8 × 106 K electron temperatures, respectively, varied across the different coronal structures intercepted by the slit. Fe xiv was the dominant emission in the closed fields of an active region and the base of a streamer, with relatively constant 20–30 km s−1 line widths independent of the height. In contrast, Fe x emission exhibited broader (>40 km s−1) line widths in open fields, which increased with height, in particular in the polar coronal hole. Inferences of line widths and Doppler shifts were consistent with extreme ultraviolet (EUV) observations from the Hinode/EUV Imaging Spectrograph, as well as with the near-infrared Fe xiii 1074 nm line observed by Coronal Multichannel Polarimeter. The differences in the spectral line widths between distinct coronal structures are interpreted as an indication of the predominance of wave heating in open structures versus localized heating in closed structures. This study underscores the unparalleled advantages and the enormous potential of TSE spectroscopy in measuring line widths simultaneously in open and closed fields at high altitudes, with minimal exposure times, stray light levels, and instrumental widths.

Shielding Mn3+ Disproportionation with Graphitic Carbon-Interlayered Manganese Oxide Cathodes for Enhanced Aqueous Energy Storage System.

Manganese dioxide (MnO2) materials have recently garnered attention as prospective high-capacity cathodes, owing to their theoretical two-electron redox reaction in charge storage processes. However, their practical application in aqueous energy storage systems faces a formidable challenge: the disproportionation of Mn3+ ions, leading to a significant reduction in their capacity. To address this limitation, the study presents a novel graphitic carbon interlayer-engineered manganese oxide (CI-MnOx) characterized by an open structure and abundant defects. This innovative material serves several essential functions for efficient aqueous energy storage. First, a graphitic carbon layer coats the MnOx molecular interlayer, effectively inhibiting Mn3+ disproportionation and substantially enhancing electrode conductivity. Second, the phase variation within MnOx generates numerous crystal defects, vacancies, and active sites, optimizing electron-transfer capability. Third, the flexible carbon layer acts as a buffer, mitigating the volume expansion of MnOx during extended cycling. The synergistic effects of these features result in the CI-MnOx exhibiting an impressive high capacity of 272 mAh g-1 (1224 F g-1) at 0.25 A g-1. Notably, the CI-MnOx demonstrates zero capacity loss after 90000 cycles (≈3011h), an uncommon longevity for manganese oxide materials. Spectral characterizations reveal reversible cation intercalation and conversion reactions with multielectron transfer in a LiCl electrolyte.

Advancing self-cleaning performance in metakaolin-based geopolymers through in-situ zeolite formation and TiO2 integration

The deterioration of self-cleaning properties of cementitious materials upon hydration was addressed by in-situ zeolite formation within metakaolin-based geopolymers. Pastes with varied in-situ zeolite content were formulated by adjusting the Si/Al ratio of initial raw materials and curing temperatures. The impact of in-situ zeolite formation on self-cleaning performance was systematically investigated through phase composition, optical property and microstructure analyses. Zeolite A formation notably enhances self-cleaning performance, despite contributing to higher band energy and lower Urbach energy. The increases in crystalline zeolite amount and matrix porosity enhances mass transfer capacity. The open pore structure of zeolite facilitates the formation of connective channels during particle growth, mitigating the “sheltering” effect of the surrounding media for photocatalysts and ensuring improved self-cleaning performance upon hydration. This study summarizes the synthesis conditions for zeolite A, providing mechanistic insights into in-situ zeolite formation in metakaolin-based geopolymers and emphasizes its promising potential for optimizing self-cleaning properties in cementitious materials.

Temporal changes in spatial scale and autocorrelation structure of forest openings based on taxonomic, phylogenetic, and functional turnover

ContextDuring European settlement, Illinois grasslands were converted for agricultural purposes. Remaining natural areas in southern Illinois include natural xeric forest openings, with communities representative of remnant grasslands and adjacent hardwood forests. Previous research in these openings shows plant communities are driven by edaphic conditions. ObjectivesThe first objective aimed to characterize spatial scale and autocorrelation structure of these openings based on climatic, environmental, and diversity variables. The second objective was to predict taxonomic, phylogenetic, and functional turnover between 1988 and 2019, using climatic and environmental variables. MethodsSurveys were conducted to calculate taxonomic, phylogenetics and functional trait metrics and analyses of these dimensions of diversity. Randomization tests were used to assess phylogenetic and functional clustering and over-dispersion at each site. Spatially-explicit climatic and environmental variables were included from earlier surveys and data repositories. Global Moran's I and spatial autocorrelograms were used to assess spatial structure of climatic, environmental, and diversity variables and generalized dissimilarity modeling was used to characterize taxonomic, phylogenetic, and functional turnover based on environmental variables. ResultsSoil depth was the only environmental variable which exhibited significant global spatial autocorrelation. Overall, sandstone sites were phylogenetically over-dispersed while loess sites were phylogenetically clustered. Climate variables and diversity metrics exhibited significant spatial structure during surveys. Generalized dissimilarity models showed that geographic distance between openings was the most influential driver of turnover across surveys. ConclusionsPrevious glacial events explained the spatial structure of soil depth across sites, due to Quaternary loess deposition in loess sites. High diversity values were clustered in the southeastern portions of the study area. Functional generalized dissimilarity models best predicted turnover in these openings compared to taxonomic and phylogenetic models.

Development and Study of Novel Ultrafiltration Membranes Based on Cellulose Acetate.

Recently, increasing attention of researchers in the field of membrane technology has been paid to the development of membranes based on biopolymers. One of the well-proven polymers for the development of porous membranes is cellulose acetate (CA). This paper is devoted to the study of the influence of different parameters on ultrafiltration CA membrane formation and their transport properties, such as the variation in coagulation bath temperature, membrane shrinkage (post-treatment at 80 °C), introduction to casting CA solution of polymers (polyethylene glycol (PEG), polysulfone (PS), and Pluronic F127 (PL)) and carbon nanoparticles (SWCNTs, MWCNTs, GO, and C60). The structural and physicochemical properties of developed membranes were studied by scanning electron and atomic force microscopies, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The transport properties of developed CA-based membranes were evaluated in ultrafiltration of bovine serum albumin (BSA), dextran 110 and PVP K-90. All developed membranes rejected 90% compounds with a molecular weight from ~270,000 g/mol. It was shown that the combination of modifications (addition of PEG, PS, PL, PS-PL, and 0.5 wt% C60) led to an increase in the fluxes and BSA rejection coefficients with slight decrease in the flux recovery ratio. These changes were due to an increased macrovoid number, formation of a more open porous structure and/or thinner top selective, and decreased surface roughness and hydrophobization during C60 modification of blend membranes. Optimal transport properties were found for CA-PEG+C60 (the highest water-394 L/(m2h) and BSA-212 L/(m2h) fluxes) and CA-PS+C60 (maximal rejection coefficient of BSA-59%) membranes.

Strength Increase of Alumina Foams by a Sodium Aluminosilicate Glass Coating with Subsequent Na+ ↔ K+ Ion Exchange (Gorilla Glass Coating)

Reticulated alumina ceramic foams manufactured by the Schwartzwalder technique are coated with a sodium aluminosilicate glass using an aqueous precursor containing alumina particles and sodium silicate. After a heat treatment, a well‐adhering glass layer with a thickness between 10 and 120 μm is obtained. Besides the strut surface, the glass phase also penetrates the hollow strut cavities as well as strut cracks. The total porosity of the glass‐coated foams is between 88% and 90%, and the open cellular structure is not negatively affected by the glass coating. The compressive strength increases by a factor of two under consideration of the decrease in total porosity; a compressive strength in the order of magnitude of 2 MPa is feasible. An ion exchange of Na+ by K+ into the glass coating layer (chemical strengthening) is successfully demonstrated, but does not result in an additional improvement of the compressive strength.

A Versatile Synthesis Platform Based on Polymer Cubosomes for a Library of Highly Ordered Nanoporous Metal Oxides Particles.

Polymer cubosomes (PCs) have well-defined inverse bicontinuous cubic mesophases formed by amphiphilic block copolymer bilayers. The open hydrophilic channels, large periods, and robust physical properties of PCs are advantageous to many host-guest interactions and yet not fully exploited, especially in the fields of functional nanomaterials. Here, the self-assembly of poly(ethylene oxide)-block-polystyrene block copolymers is systematically investigated and a series of robust PCs is developed via a cosolvent method. Ordered nanoporous metal oxide particles are obtained by selectively filling the hydrophilic channels of PCs via an impregnation strategy, followed by a two-step thermal treatment. Based on this versatile PC platform, the general synthesis of a library of ordered porous particles with different pore structures , tunable large pore size (18-78nm), high specific surface areas (up to 123.3m2g-1 for WO3) and diverse framework compositions, such as transition and non-transition metal oxides, rare earth chloride oxides, perovskite, pyrochlore, and high-entropy metal oxides is demonstrated. As typical materials obtained via this method, ordered porous WO3 particles have the advantages of open continuous structure and semiconducting properties, thus showing superior gas sensing performances toward hydrogen sulfide.

Activation of 2D/3D zeolitic-imidazole frameworks affecting crystal properties and adsorption performance

The zeolitic-imidazole frameworks (ZIFs) have become popular due to their uniformly structured cavities and portals of framework dimensions, which make them suitable for numerous applications. In order to access pores and functional surfaces, thermal activation is significantly post-treatment on the synthesis of ZIFs for their applications. This study explores the impact of different thermal activation conditions on two- to three-dimensional ZIFs, which significantly affect their structure, morphology, and properties. Their transform structure is evidenced by integrated X-ray diffraction technique, Thermogravimetric analysis, Scanning electron microscope, and Fourier transform infrared spectroscopy. Moreover, the performance of greenhouse gas adsorption (CO2 and CH4) applications is affected by the transformation through the thermal activation of materials. Therefore, understanding the activated conditions that impact material synthesis is crucial to maximizing the potential applications of ZIFs in various fields. The 2D ZIF-L has more exposed external surfaces and open structures, which makes it more reactive towards adsorptive reactants, unlike the 3D ZIFs. The 3D ZIFs have a robust structure and a higher porosity framework that can withstand challenging application conditions. Thus, it's essential to ensure appropriate activation conditions to maintain the functional properties of ZIFs, which are crucial for their optimal performance in various applications.

Achieving Long Cycle Life of Zn-Ion Batteries through Three-Dimensional Copper Foam.

Metallic zinc anodes in aqueous zinc-ion batteries (ZIBs) suffer from dendritic growth, low Coulombic efficiency, and high polarization during cycling. To mitigate these challenges, current collectors based on three-dimensional (3D) commercial copper foam (CCuF) are generally preferred. However, their utilization is constrained by their thickness, low electroactive surface area, and increased manufacturing expenses. In this study, the synthesis of cost-effective current collectors with exceptionally large surface areas designed for ZIBs that can be cycled hundreds of times is reported. A zinc-coated CuF anode (Zn/CuF) was prepared with a 3D porous CuF current collector produced by the dynamic hydrogen bubble template (DHBT) method. Electrochemically generated copper foam could be obtained within seconds while offering a thickness as low as 30-40 μm (CuF5 achieved a thickness of ∼38 μm in 5 s) via the DHBT method. The excellent electrical conductivity and open pore structure of the 3D porous copper scaffold ensured the uniform deposition/stripping of Zn during cycling. During the 500 h Zn deposition/stripping process, the as-synthesized CuF5 current collector offered fast electrochemical kinetics and low polarization as well as a relatively high average Coulombic efficiency of 99% (at a current density of 5 mA cm-2 and a capacity of 1 mAh cm-2). Furthermore, the symmetric cell exhibited low voltage polarization and a stable voltage profile for 1000 h at a current density of 0.1 mA cm-2. In addition, full cells containing the Zn/CuF anode coupled with an as-synthesized α-MnO2 nanoneedle cathode in aqueous electrolyte were also prepared. Capacities of 266 mAh g-1 at 0.1 A g-1 and 94 mAh g-1 at 2 A g-1 were achieved after 200 charge/discharge cycles with a stable Coulombic efficiency value close to 99.9%.

Sub-millisecond lithiothermal synthesis of graphitic meso–microporous carbon

Porous carbons with concurrently high specific surface area and electronic conductivity are desirable by virtue of their desirable electron and ion transport ability, but conventional preparing methods suffer from either low yield or inferior quality carbons. Here we developed a lithiothermal approach to bottom–up synthesize highly meso–microporous graphitized carbon (MGC). The preparation can be finished in a few milliseconds by the self-propagating reaction between polytetrafluoroethylene powder and molten lithium (Li) metal, during which instant ultra-high temperature (>3000 K) was produced. This instantaneous carbon vaporization and condensation at ultra-high temperatures and in ultra-short duration enable the MGC to show a highly graphitized and continuously cross-coupled open pore structure. MGC displays superior electrochemical capacitor performance of exceptional power capability and ultralong-term cyclability. The processes used to make this carbon are readily scalable to industrial levels.

Interface engineering of hierarchical flower-like N, P, O-doped NixPy self-supported electrodes for highly efficient water-to-hydrogen fuel/oxygen conversion

Rational construction of efficient bifunctional catalysts with robust catalytic activity and durability is significant for overall water splitting (conversion between water and hydrogen fuel/oxygen) using non-precious metal systems. In this work, the hierarchically porous N, P, O-doped transition metal phosphate in the Ni foam (NF) electrode (hollow flower-like NPO/NixPy@NF) was prepared through facile hydrothermal method coupled with phosphorization treatment. The hierarchical hollow flower-like NPO/NixPy@NF electrodes exhibited high bifunctional activity and stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solutions. The optimized electrode showed low overpotentials of 76 and 240 mV for HER and OER to reach a current density of 10 mA cm−2, respectively. Notably, the NPO/NixPy@NF electrode only required a low voltage of 1.99 V to reach the current densities of 100 mA cm−2 with long-term stability for overall water splitting using the NPO/NixPy@NF|| NPO/NixPy@NF cell, surpassing that of the Pt/C-RuO2 (2.24 V@ 100 mA cm−2). The good catalytic and battery performance should be attributed to i) the open hierarchical structure that enhanced the mass transfer; ii) a highly conductive substrate that accelerated the electron transfer; iii) the rich heterojunction and strong synergy between Ni2P and Ni5P4 that improved the catalytic kinetic; iv) the proper-thickness amorphous phosphorus oxide nitride (PON) shell that realized the stability. This work demonstrates a promising methodology for designing bifunctional transition metal phosphides with high performance for efficient water splitting.

Dynamic In Vitro Gastric Digestion Behaviour of Commercial Infant Formulae Made with Cow, Goat and Sheep Milk.

There are a wide range of commercial infant formulae available on the market. These are made using milk from different species, such as goat, sheep, and cow. The different protein compositions of these milks and the process used during infant-formulae manufacture, such as heat treatment, may impact the digestion of nutrients. This study compared the effect of protein composition and heat treatment on the in vitro gastric digestion behaviour of commercial infant formulae made with cow, goat, and sheep milk using a dynamic infant human gastric simulator (IHGS). During the simulated dynamic gastric digestion, the goat milk infant formula (GIF) showed earlier signs of aggregate formation compared to cow milk infant formula (CIF) and sheep milk infant formula (SIF). In addition, the microstructures of GIF chyme showed fragmented and porous structures. On the contrary, CIF formed dense protein networks that trapped oil droplets, whereas SIF exhibited a microstructure of smooth oil droplets surrounded by fewer protein networks. The different aggregation behaviours and aggregate structures of the three infant-formulae chyme were related to their different protein compositions, especially the different casein compositions. Furthermore, the open fragile structure of GIF aggregates provided easier access to pepsin, allowing it to hydrolyse protein. The results from the present study provided some information to assist in understanding the coagulation and digestion behaviours of commercial infant formulae made from different species of milk.

Intercalating polypyrrole tuning interlayer space of V2O5 for advanced aqueous zinc ion batteries

Aqueous zinc-ion batteries is considered as a promising system for large scale electrochemical energy storage system owing to their intrinsic safety, and low cost. Nevertheless, the industrialization process is slow due to the constraints of high-performance cathode materials. Adjusting the layered structure of V2O5 through metal ion or polymer intercalation can effectively improve low electron conductivity, vanadium dissolution, and slow ion transport kinetics. Herein, the conductive polymer polypyrrole-intercalated V2O5·H2O (PVOH) was successfully prepared via simple hydrothermal method and following interface polymerization reaction. Getting benefit from the insertion of polypyrrole, the prepared PVOH composite material achieves a V2O5 cathode with a more open structure, rich active sites, and greater stability, allowing for an expanded crystal plane spacing of 14.5 Å. Therefore, the PVOH electrode demonstrates a discharge capacity of 475 mAh g−1 and a cycling stability of 95% capacity retention after 2000 cycles. The intercalating conductive polymers strategy can become a new approach to improve the electrochemical behavior of vanadium oxide cathodes.

Prussian Blue Nanoplates for Potassium Ion Battery Cathode with High Capacity and High Energy Density

AbstractPrussian blue analogues (PBAs) represent as a class of materials with an open framework structure and have been intensively explored as the potential active materials for alkaline‐ion batteries. Here, we present the synthesis of Prussian blue nanoplates designed for use as high performance cathode materials in potassium‐ion batteries. Prussian blue nanoplates were synthesized through a facile solution precipitation route using a highly concentrated potassium citrate solution. The potassium‐rich environment during the synthesis facilitated horizontal growth of the crystals, yielding potassium‐rich Prussian blue nanoplates. The resultant Prussian blue nanoplates exhibited a significantly larger particle size of 600 nm and a reduced specific surface area of 6.8 m2 g−1, compared to conventionally synthesized Prussian blue hexahedrons. Half‐cell tests demonstrated that the Prussian blue nanoplates exhibited a high gravimetric capacity of 152.5 mAh g−1 with a nominal voltage 3.952 V at a C‐rate of 0.1 C, yielding an energy density of 602.7 Wh kg−1. Cycling tests demonstrated high cycling stability of the material, maintaining a capacity of 122.7 mAh g−1 and a nominal voltage of 3.923 V after 200 cycles at 0.2 C. In a full‐cell configuration with graphite anodes, a gravimetric capacity changed from 134.1 mAh g−1 to 108.9 mAh g−1 after 100 cycles at 0.2 C, demonstrating a good cycling stability. This work provides a new insight into the electrochemical properties of Prussian blue nanoplates and highlights their potential as high‐performance cathode materials for potassium‐ion batteries.

Superporous Hydrogel: A Novel Approach for Safe Gastroretentive Drug Delivery System

Superporous hydrogel are developed initially as novel drug delivery system to retain dosage form in upper gastrointestinal tract, and absorbs drug in gastric medium. The generation-based classification of superporous hydrogel is covered in this review. The hydrophilic polymer networks formed by the molecular entanglements which absorb water up to thousands of times to their dry weight. These systems swells quickly and resist in an extremely acidic condition in stomach. This hydrogel is instantly swell through capillary force which is driven by absorption of water through an open porous structure. This system provides better solubility and bioavailability by targeting the specific site of absorption. The conventional superporous hydrogels have the poor mechanical strength which is overcome by developing the second superporous hydrogel generation composites and the third-generation superporous hydrogel hybrids. This article has mainly focused on the classification, techniques, drug loading, research papers, characterizations and applications of superporous hydrogel.&#x0D; Keywords: Gastric retention, Cross-linking, Superporous hydrogel, Swelling rate, Elastic property, Hydrophilic polymer networks.

Preparation of three-dimensionally interconnected sulfur-deficient MoS2/nitrogen-doped carbon composite via salt template method for separator modification in lithium–Sulfur batteries

Separator modification is a promising strategy with regard to lithium–sulfur batteries for trapping polysulfides and suppressing the involved shuttle effect. Herein, a sulfur-deficient molybdenum disulfide/nitrogen-doped carbon composite with an open and interconnected structure (IMoS2-x) was synthesized through facile salt template method using recrystallized salt powder. Unlike the two-dimensional sheet structure obtained through conventional salt template method, an effective three-dimensional IMoS2-x composite design can be achieved using small salt powder as a template. The prepared IMoS2-x-coated polypropylene separator (referred to as IMoS2-x/PP) exhibited remarkable electrochemical performances such as high initial discharge capacity of 1405.1 mAh/g and rate capability of 754.16 mAh/g at 0.1 and 3C, respectively. Furthermore, IMoS2-x/PP exhibited robust cycling performance of 911.18 mAh/g after 80 cycles at 0.2C under high sulfur loading and lean electrolyte conditions, with the electrolyte-to-sulfur ratio (E/S ratio) of 7.5 μL mg−1.

High‐Resolution 3D Printing of Dual‐Curing Thiol‐Ene/Epoxy System for Fabrication of Microfluidic Devices for Bioassays

AbstractThe customized processing of polymer materials in the microscale by high‐resolution 3D printing provides an easy access to advanced applications in the fields of optics, microfluidics, tissue engineering, and life science. However, the 3D printing of enclosed structures in the scale of tens of microns such as closed microfluidic channels remains a challenge as channel structures often are clogged by residual cured resin. Dual‐curing systems based on off‐stoichiometric thiol‐ene and thiol‐ene/epoxy chemistry are well‐known for adhesive‐free bonding in the fabrication of cast or injection molded microfluidic devices. Herein, the first high‐resolution stereolithography 3D printing of a dual‐curing thiol‐ene/epoxy system in the microscale for the fabrication of customized microfluidic devices is presented. In the first curing step, by high‐resolution 3D printing open microfluidic structures are produced. Consecutively, the microchannels are sealed by adhesive‐free dry bonding upon thermal initiation, producing well‐controlled structures with channel sizes down to 80 µm. Before bonding, the intermediate material allows for tailored surface modification with biotin, which allows for consecutive immobilization of various biomolecules. A DNA‐bioassay with specific patterning is shown in the sealed chip. The presented work paves the way toward the fabrication of customized microfluidic devices for a large range of specific bioassays.

γ-TuRC asymmetry induces local protofilament mismatch at the RanGTP-stimulated microtubule minus end

The γ-tubulin ring complex (γ-TuRC) is a structural template for de novo microtubule assembly from α/β-tubulin units. The isolated vertebrate γ-TuRC assumes an asymmetric, open structure deviating from microtubule geometry, suggesting that γ-TuRC closure may underlie regulation of microtubule nucleation. Here, we isolate native γ-TuRC-capped microtubules from Xenopus laevis egg extract nucleated through the RanGTP-induced pathway for spindle assembly and determine their cryo-EM structure. Intriguingly, the microtubule minus end-bound γ-TuRC is only partially closed and consequently, the emanating microtubule is locally misaligned with the γ-TuRC and asymmetric. In the partially closed conformation of the γ-TuRC, the actin-containing lumenal bridge is locally destabilised, suggesting lumenal bridge modulation in microtubule nucleation. The microtubule-binding protein CAMSAP2 specifically binds the minus end of γ-TuRC-capped microtubules, indicating that the asymmetric minus end structure may underlie recruitment of microtubule-modulating factors for γ-TuRC release. Collectively, we reveal a surprisingly asymmetric microtubule minus end protofilament organisation diverging from the regular microtubule structure, with direct implications for the kinetics and regulation of nucleation and subsequent modulation of microtubules during spindle assembly.