Heterophase Intermetallic Compounds for Electrocatalytic Hydrogen Production at Industrial-Scale Current Densities.

Heterophase nanomaterials have sparked significant research interest in catalysis due to their distinctive properties arising from synergistic effects of different components and the formed phase boundary. However, challenges persist in the controlled synthesis of heterophase intermetallic compounds (IMCs), primarily due to the lattice mismatch of distinct crystal phases and the difficulty in achieving precise control of the phase transitions. Herein, orthorhombic/cubic Ru2Ge3/RuGe IMCs with engineered boundary architecture are synthesized and anchored on the reduced graphene oxide. The Ru2Ge3/RuGe IMCs exhibit excellent hydrogen evolution reaction (HER) performance with a high current density of 1000 mA cm-2 at a low overpotential of 135 mV. The presence of phase boundaries enhances charge transfer and improves the kinetics of water dissociation while optimizing the processes of hydrogen adsorption/desorption, thus boosting the HER performance. Moreover, an anion exchange membrane electrolyzer is constructed using Ru2Ge3/RuGe as the cathode electrocatalyst, which achieves a current density of 1000 mA cm-2 at a low voltage of 1.73 V, and the activity remains virtually undiminished over 500 h.

Preparation of a Gradient Anti-Oxidation Coating for Aircraft C/C Composite Brake Disc and Its High-Temperature In Situ Self-Healing Performance.

We studied a gradient anti-oxidation coating of C/C composite materials for aircraft brake discs with a simple process and low costs. The gradient coating consists of two layers, of which the inner layer is prepared with tetraethyl orthosilicate (Si (OC2H5)4), C2H5OH, H3PO4 and B4C, and the outer layer is prepared with Na2B4O7.10H2O, B2O3, and SiO2 powder. The experimental results show that after being oxidized at 700 °C for 15 h, the oxidation weight loss of the sample with the coating was only -0.17%. At the same time, after 50 thermal cycles in air at 900 °C, the sample's oxidation weight loss was only -0.06%. We conducted the 1:1 dynamic simulation test for aircraft brake discs, and the brake disc did not oxidize, thus meeting the requirements for aircraft use. In addition, the anti-oxidation mechanism of the coating was analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal analysis (DSC-TGA), and high-temperature in situ SEM.

Insight into the Nucleation Mechanism of p-Methoxybenzoic Acid in Ethanol-Water System from Metastable Zone Width.

The metastable zone width (MSZW) of p-methoxybenzoic acid (PMBA) in an ethanol-water system was measured using the polythermal method. The nucleation order m obtained by the Nývlt's model indicates the nucleation of PMBA following a progressive nucleation mechanism at low saturation temperature (m = 3.18-7.50) and an instantaneous nucleation mechanism at high saturation temperature (m = 1.46-2.55). Then, combined with the metastable zone experiment and the Sangwal model, we found that the MSZW and the interfacial energy reached the maximum when the mass fraction of ethanol was 0.8, which resulted in the smallest crystal product size. Meanwhile, the maximum rcrit and ΔGcrit obtained based on the modified Sangwal model indicating the PMBA needs to overcome a higher nucleation barrier in the ethanol mass fraction of 0.8. Finally, we proposed a preferential strategy for adjusting MSZW by correlating the interfacial energy with the change in ethanol mass fraction, saturation temperature, and cooling rate, respectively.

Leaf Mutant 7 Encoding Heat Shock Protein OsHSP40 Regulates Leaf Size in Rice.

Leaf size is an important agronomic trait directly affecting yield in rice, and thus understanding the genes determining leaf size is important in breeding. In this study, one Leaf Mutant 7 (lm7) with small leaf size was isolated using ethyl methane sulphonate (EMS) mutagenesis from the japonica Zhenggeng 1925. MutMap by whole genome resequencing of phenotypic bulks revealed that LM7 is likely located in the 133 kb region on chromosome 7 using F2 population from a cross between lm7 and wild-type (WT) Zhenggeng 1925. The candidate gene encoding heat shock protein OsHSP40 for LM7 was functionally validated. Disruption of this gene in Oshsp40 mutants significantly reduced the leaf size compared with that of WT in rice. Microscopic examination showed that OsHSP40 modulated leaf size via regulating the veins formation and cell size/cell number. Nucleotide diversity analysis indicated that a single nucleotide polymorphism (SNP) variation of C to T in the coding region of OsHSP40 may cause small leaves among rice accessions. Therefore, the natural variation of OsHSP40 contributing to leaf size might be useful for rice breeding.

Effects of gibberellin priming on seedling emergence and transcripts involved in mesocotyl elongation in rice under deep direct-seeding conditions.

Mesocotyl elongation is a key trait influencing seedling emergence and establishment in direct-seeding rice cultivation. The phytohormone gibberellin (GA) has positive effects on mesocotyl elongation in rice. However, the physiological and molecular basis underlying the regulation of mesocotyl elongation mediated by GA priming under deep-sowing conditions remains largely unclear. In the present study, we performed a physiological and comprehensive transcriptomic analysis of the function of GA priming in mesocotyl elongation and seedling emergence using a direct-seeding japonica rice cultivar ZH10 at a 5-cm sowing depth. Physiological experiments indicated that GA priming significantly improved rice seedling emergence by increasing the activity of starch-metabolizing enzymes and compatible solute content to supply the energy essential for subsequent development. Transcriptomic analysis revealed 7074 differentially expressed genes (false discovery rate of <0.05, |log2(fold change)| of ≥1) after GA priming. Furthermore, gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses revealed that genes associated with transcriptional regulation, plant hormone biosynthesis or signaling, and starch and sucrose metabolism were critical for GA-mediated promotion of rice mesocotyl elongation. Further analyses showed that the expression of the transcription factor (TF) genes (v-myb avian myeloblastosis viral oncogene homolog (MYB) alternative splicing 1 (MYBAS1), phytochrome-interacting factors 1 (PIF1), Oryza sativa teosinte branched 1/cycloidea/proliferating cell factor 5 (OsTCP5), slender 1 (SLN1), and mini zinc finger 1 (MIF1)), plant hormone biosynthesis or signaling genes (brassinazole-resistant 1 (BZR1), ent-kaurenoic acid oxidase-like (KAO), GRETCHEN HAGEN 3.2 (GH3.2), and small auxin up RNA 36 (SAUR36)), and starch and sucrose metabolism genes (α-amylases (AMY2A and AMY1.4)) was highly correlated with the mesocotyl elongation and deep-sowing tolerance response. These results enhance our understanding of how nutrient metabolism-related substances and genes regulate rice mesocotyl elongation. This may facilitate future studies on related genes and the development of novel rice varieties tolerant to deep sowing.

Iterative Cup Overlapping: An Efficient Identification Algorithm for Cage Structures of Amorphous Phase Hydrates.

Molecular dynamics studies have revealed that the nucleation pathway of clathrate hydrates involves the evolution from amorphous to crystalline hydrates. In this study, complete cages are further classified into the standard edge-saturated cages (SECs) and nonstandard edge-saturated cages (non-SECs). Centered on studying the structure and evolution of non-SECs and SECs, we propose a novel and efficient algorithm, iterative cup overlapping (ICO), to monitor hydrate nucleation and growth in molecular simulations by identifying SECs and discuss possible causes of the instability of non-SECs. Manipulation of topological information makes it possible for ICO to avoid the repeated searches for identified cages and deduce all SECs with low time costs, improving the efficiency of identification significantly. The accuracy and efficiency of ICO were verified by comparing the identification results with other well-proven algorithms. Furthermore, it was found that non-SECs have short lifetimes and eventually decompose or reorganize into more stable structures. Some evidence suggests that the instability of non-SECs is closely related to the hydrogen-bonding configuration of water-ring aggregations that they contain. The spontaneous evolution of the hydrogen-bonding network into the tetrahedral network may be the main factor that causes the conversion of QWRAs and the evolution of non-SECs.

Prelithiated V2 C MXene: A High-Performance Electrode for Hybrid Magnesium/Lithium-Ion Batteries by Ion Cointercalation.

The pursuit of high reversible capacity and long cycle life for rechargeable batteries has gained extensive attention in recent years, and the development of applicable electrode materials is the key point. Herein, thanks to the preintercalation of lithium ions, a stable and highly conductive nanostructure of V2 C MXene is successfully fabricated via a facile self-discharge mechanism, which provides open spaces for rapid ion diffusion and guarantees fast electron transport. Taking the prelithiated V2 C as electrode, an outstanding initial coulombic efficiency of 80% and an impressive capacity retention of ≈98% after 5000 charge/discharge cycles are achieved for lithium-ion batteries. Especially, it demonstrates a fascinating reversible capacity of up to 230.3 mA h g-1 at 0.02 A g-1 and a long cycling life of 82% capacity retention over 480 cycles in the hybrid magnesium/lithium-ion batteries. In addition, the Mg2+ and Li+ ions cointercalation mechanism of the prelithiated V2 C is elucidated through ex situ X-ray diffraction and X-ray photoelectron spectroscopy characterizations. This work not only offers an effective approach to compensate the large initial lithium loss of high-capacity anode materials but also opens up a new and viable avenue to develop promising hybrid Mg/Li-storage materials with eminent electrochemical performance.

Effects of Compaction Velocity on the Sinterability of Al-Fe-Cr-Ti PM Alloy.

In this research, the effects of the compaction velocity on the sinterability of the Al-Fe-Cr-Ti powder metallurgy (PM) alloy by high velocity compaction were investigated. The Al-Fe-Cr-Ti alloy powder was compacted with different velocities by high velocity compaction and then sintered under a flow of high pure (99.999 wt%) nitrogen gas. Results indicated that both the sintered density and mechanical properties increased with increasing compaction velocity. By increasing the compaction velocity, the shrinkage of the sintered samples decreased. A maximum sintered density of 2.85 gcm-3 (relative density is 98%) was obtained when the compaction velocity was 9.4 ms-1. The radial and axial shrinkage were controlled to less than 1% at a compaction velocity of 9.4 ms-1. At a compaction velocity of 9.4 ms-1, sintered compacts with an ultimate tensile strength of 222 MPa and a yield strength of 160 MPa were achieved. The maximum elongation was observed to be 2.6%. The enhanced tensile properties of the Al-Fe-Cr-Ti alloy were mainly due to particle boundary strengthening.

First-Principles Study on the Mechanical Properties and Electronic Structure of V Doped WCoB and W2CoB2 Ternary Borides.

For the purpose of exploring new hard materials and doping methods, the structural, mechanical and electronic properties of WCoB and W2CoB2 ternary boride were investigated with 0, 8.33, 16.67, 25 and 33.33 at.% V doping content and W2CoB2 with 0, 5, 10, 15 and 20 at.% V doping content by first-principle calculations. The cohesive energy, impurity formation energy and formation energy indicate the structural stability of V doped WCoB and W2CoB2. The elastic constants and mechanical properties imply that V doping leads to the decrement of shear modulus and the increment of ductility. Two different kinds of hardness models verify that V doping contributes to the decrement of hardness, which is closely related to shear modulus. The electronic structure is analyzed by DOS (density of states), PDOS (partial density of states) and charge density difference, which indicate the formation of weaker B⁻V covalent bonds, W⁻V and W⁻W metallic bonds lead to the decrement of mechanical properties. Compared with previous studies of Cr, Mn doped WCoB and W2CoB2, V doping leads to worse mechanical properties and hardness, indicating V may not be a suitable choice of doping transition elements.

Molecular identification and interaction assay of the gene (OsUbc13) encoding a ubiquitin-conjugating enzyme in rice.

The ubiquitin (Ub)-conjugating enzyme, Ubc13, has been known to be involved in error-free DNA damage tolerance (or post-replication repair) via catalyzing Lys63-linked polyubiquitin chains formation together with a Ubc variant. However, its functions remain largely unknown in plant species, especially in monocotyledons. In this study, we cloned a Ub-conjugating enzyme, OsUbc13, that shares the conserved domain of Ubc with AtUBC13B in Oryza sativa L., which encodes a protein of 153 amino acids; the deduced sequence shares high similarities with other homologs. Real-time quantitative polymerase chain reaction (PCR) indicated that OsUbc13 transcripts could be detected in all tissues examined, and the expression level was higher in palea, pistil, stamen, and leaf, and lower in root, stem, and lemma; the expression of OsUbc13 was induced by low temperature, methylmethane sulfate (MMS), and H(2)O(2), but repressed by mannitol, abscisic acid (ABA), and NaCl. OsUbc13 was probably localized in the plasma and nuclear membranes. About 20 proteins, which are responsible for the positive yeast two-hybrid interaction of OsUbc13, were identified. These include the confirmed OsVDAC (correlated with apoptosis), OsMADS1 (important for development of floral organs), OsB22EL8 (related to reactive oxygen species (ROS) scavenging and DNA protection), and OsCROC-1 (required for formation of Lys63 polyubiquitylation and error-free DNA damage tolerance). The molecular characterization provides a foundation for the functional study of OsUbc13.

Effects of cholesterol incorporation on the physicochemical, colloidal, and biological characteristics of pH-sensitive AB2 miktoarm polymer-based polymersomes.

In our previous study, a histidine-based AB2 miktoarm polymer, methoxy poly(ethylene glycol)-b-poly(l-histidine)2 (mPEG-b-(PolyHis)2), was designed to construct pH-sensitive polymersomes that transform in acidic pH; the polymer self-assembles into a structure that mimics phospholipids. In this study, the polymersomes further imitated liposomes due to the incorporation of cholesterol (CL). The hydrodynamic radii of the polymersomes increased with increasing CLwt% (e.g., 70 nm for 0 wt% vs. 91 nm for 1 wt%), resulting in an increased capacity for encapsulating hydrophilic drugs (e.g., 0.92 µL/mg for 0 wt% vs. 1.42 µL/mg for 1 wt%). The CL incorporation enhanced the colloidal stability of the polymersomes in the presence of serum protein and retarded their payload release. However, CL-incorporating polymersomes still demonstrated accelerated release of a hydrophilic dye (e.g., 5(6)-carboxyfluorescein (CF)) below pH 6.8 without losing their desirable pH sensitivity. CF-loaded CL-incorporating polymersomes showed better cellular internalization than the hydrophilic CF, whereas doxorubicin (DOX)-loaded CL-incorporating polymersomes presented similar or somewhat lower anti-tumor effects than free hydrophobic DOX. The findings suggest that CL-incorporating mPEG-b-(PolyHis)2-based polymersomes may have potential for intracellular drug delivery of chemical drugs due to their improved colloidal stability, lower drug loss during circulation, acidic pH-induced drug release, and endosomal disruption.

Biocompatible, pH-sensitive AB(2) Miktoarm Polymer-Based Polymersomes: Preparation, Characterization, and Acidic pH-Activated Nanostructural Transformation.

Motivated by the limitations of liposomal drug delivery systems, we designed a novel histidine-based AB(2)-miktoarm polymer (mPEG-b-(polyHis)(2)) equipped with a phospholipid-mimic structure, low cytotoxicity, and pH-sensitivity. Using "core-first" click chemistry and ring-opening polymerization, mPEG(2kDa)-b-(polyHis(29kDa))(2) was successfully synthesized with a narrow molecular weight distribution (1.14). In borate buffer (pH 9), the miktoarm polymer self-assembled to form a nano-sized polymersome with a hydrodynamic radius of 70.2 nm and a very narrow size polydispersity (0.05). At 4.2 µmol/mg polymer, mPEG(2kDa)-b-(polyHis(29kDa))(2) strongly buffered against acidification in the endolysosomal pH range and exhibited low cytotoxicity on a 5 d exposure. Below pH 7.4 the polymersome transitioned to cylindrical micelles, spherical micelles, and finally unimers as the pH was decreased. The pH-induced structural transition of mPEG(2kDa)-b-(polyHis(29kDa))(2) nanostructures may be caused by the increasing hydrophilic weight fraction of mPEG(2kDa)-b-(polyHis(29kDa))(2) and can help to disrupt the endosomal membrane through proton buffering and membrane fusion of mPEG(2kDa)-b-(polyHis(29kDa))(2). In addition, a hydrophilic model dye, 5(6)-carboxyfluorescein encapsulated into the aqueous lumen of the polymersome showed a slow, sustained release at pH 7.4 but greatly accelerated release below pH 6.8, indicating a desirable pH sensitivity of the system in the range of endosomal pH. Therefore, this polymersome that is based on a biocompatible histidine-based miktoarm polymer and undergoes acid-induced transformations could serve as a drug delivery vehicle for chemical and biological drugs.

Microstructures and rheological dynamics of viscoelastic solutions in a catanionic surfactant system.

Viscoelastic solutions formed in a catanionic surfactant system of dodecyltriethylammonium bromide (DTEAB)/sodium dodecylsulfate (SDS) at the molar ratio of 27/73 were systematically studied using a combination of rheology and dynamic light scattering (DLS). Wormlike micelles began to form above the total surfactant concentration (C(total)) of 120 mM by the growth of small cylindrical micelles. Subsequently the system was found to exhibit linear viscoelasticity with characteristic of a Maxwell fluid in the intermediate concentration range of 170-210 mM, which arose from a 3D entangled network of wormlike micelles. At higher surfactant concentrations, a transition from linear micelles to branched structures probably took place. Finally and significantly, the effect of the surfactant headgroup on the rheological property of catanionic surfactant mixtures was discussed.

Physicochemical aspects of doxorubicin-loaded pH-sensitive polymeric micelle formulations from a mixture of poly(L-histidine)-b-poly(ethylene glycol)/poly(L-lactide)-b-poly(ethylene glycol) [corrected].

In this study, doxorubicin (DOX) was physically incorporated into pH-sensitive micelles made from a mixture of poly(L-histidine)-b-poly(ethylene glycol)/poly(L-lactide)-b-poly(ethylene glycol) (75/25, wt.%). The DOX-loaded mixed micelles were formulated using dialysis methods and optimal DOX incorporation was achieved at a drug/polymer feed ratio of 0.2 (wt./wt.) when a proper amount of aqueous phase (0.2, v./v.) was added into the common solvent (DMSO) solution, followed by dialysis at 4 degrees C. Based on the results obtained from dynamic light scattering, UV-Vis absorption, and fluorescence experiments, it was demonstrated that the encapsulated drugs were mainly located inside the hydrophobic micelle cores, well protected and inaccessible to the exterior molecules. Under in vitro conditions, although the microstructure of the micelles was altered below pH 8.0 by the encapsulated drugs, the drug-loaded micelles still exhibited a desirable ability to control the drug release in response to tumor extracellular pH.

Physicochemical characteristics of pH-sensitive poly(L-histidine)-b-poly(ethylene glycol)/poly(L-lactide)-b-poly(ethylene glycol) mixed micelles.

A novel pH-sensitive polymeric micellar system composed of poly(L-histidine)-b-poly(ethylene glycol) and poly(L-lactide)-b-poly(ethylene glycol) block copolymers was studied by dynamic/static light scattering, spectrofluorimetry and differential scanning calorimetry. The mixed micelles displayed ultra Ph Sensitivity Which Could Be Tuned By Varying The Mixing Ratio Of The Two Polymers. In Particular, Mixed Micelles Composed Of 25 Wt.% Poly(L-lactide)-b-poly(ethylene glycol) exhibited desirable pH dependency which could be used as a drug delivery system that selectively targeted the extracellular pH of acidic solid tumors. Micelles were quite stable from pH 7.4 to 7.0 but underwent a two-stage destabilization as pH decreased further. A significant increase in size and aggregation number was observed when pH dropped to 6.8. Further disruption of the micelle core eventually caused phase separation in the micelle core and dissociation of ionized poly(L-histidine)-b-poly(ethylene glycol) molecules from the micelles as pH decreased to 6.0. Increased electrostatic repulsions which arise from the progressive protonation of imidazole rings overwhelming the hydrophobic interactions among uncharged neutral blocks is considered to be the mechanism for destabilization of the micelle core.

Temperature-sensitive aqueous surfactant two-phase system formation in cationic-anionic surfactant systems.

Temperature-induced aqueous surfactant two-phase system (T-ASTP), which was found to be of generic importance, was investigated in a series of conventional mixed cationic-anionic surfactant systems. On the basis of the investigations of turbidity, dynamic light scattering, transmission electron microscopy, and fluorescence resonance energy transfer, the formation of T-ASTP can be attributed to temperature-induced vesicle aggregation. Aggregated vesicles existed in the upper part, while the separated vesicles existed in the lower part. The phase separation temperature can be regulated by varying the surfactant composition or adding additives, such as d-sorbitol, urea, or NaBr. The hydrophobic interaction and cooperative effect between cationic and anionic surfactants played a significant role in the formation of T-ASTP.

Temperature-induced vesicle aggregation in catanionic surfactant systems: the effects of the headgroup and counterion.

The peculiar nature of temperature-induced vesicle aggregation (TIVA) in some catanionic surfactant systems is systematically investigated. On the basis of a general analysis of the intervesicular interactions, the main driving force for this phenomenon is considered to be the intervesicular hydrophobic interaction among the exposed hydrophobic part of the surfactant headgroups. The addition of an oppositely charged hydrophobic salt to the catanionic vesicle systems is also found to promote the occurrence of TIVA. In fact, TIVA can be induced in ordinary catanionic vesicle systems by the addition of an oppositely charged hydrophobic counterion.

Micelle-to-vesicle transition induced by organic additives in catanionic surfactant systems.

A micelle-to-vesicle transition (MVT) induced by the addition of a series of apolar hydrocarbons (n-butylbenzene, n-hexane, n-octane, and n-dodecane) to the catanionic surfactant system n-dodecyltriethylammonium bromide/sodium n-dodecylsulfate (DTEAB/SDS) has been investigated for the first time by means of rheology and turbidity measurements, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Interestingly, a MVT can take place within certain micellar regions, which are dependent on the structure and chain length of the hydrocarbon. However, these hydrocarbons are unable to induce a MVT in another catanionic surfactant system, namely, n-dodecyltriethylammonium bromide/sodium n-dodecylsulfonate (DTEAB/SDSO(3)), in which the molecular interactions are weaker than in the DTEAB/SDS system. On the other hand, polar additives, such as n-octanol and n-octylamine, exhibit much higher efficiency and activity in inducing MVT than hydrocarbons in both DETAB/SDS and DTEAB/SDSO(3). Moreover, DLS, TEM, and time-resolved fluorescence quenching (TRFQ) results demonstrate that the ratio of vesicles to micelles in the system can be actively controlled by addition of polar additives. Possible mechanisms for the above phenomena are presented, and the potential application of controllable micelle/vesicle systems in the synthesis of tailored bimodal mesoporous materials is discussed.

Temperature-controlled vesicle aggregation in the mixed system of sodium n-dodecyl sulfate/n-dodecyltributylammonium bromide.

Temperature-controlled vesicle aggregation was investigated in a catanionic surfactant system of sodium n-dodecyl sulfate/n-dodecyltributylammonium bromide. Vesicle aggregation took place as the temperature reached the critical value (Tc). Tc can be adjusted by the variations of the total surfactant concentration and the mixed molar ratio. It was also found that the temperature variation above Tc can greatly influence the vesicle aggregation rate. The vesicle aggregation process was irreversible as long as T >/= Tc, whereas the vesicle disaggregation process occurred only below Tc.