Surface Engineering and Programmed Self-Assembly of Silica Nanoparticles with Controllable Polystyrene/Poly(4-vinybenzyl azide) Patches.

The programmed self-assembly of patchy nanoparticles (NPs) through a bottom-up approach is an efficient strategy for producing highly organized materials with a predetermined architecture. Herein, we report the preparation of di- and trivalent silica NPs with polystyrene (PS)/poly(4-vinylbenzyl azide) (PVBA) patches and assemble them in a THF mixture by lowering the solvent quality. Silica-PS/PVBA colloidal hybrid clusters were synthesized through the seeded growth emulsion copolymerization of styrene and 4-vinylbenzyl azide (VBA) in varying ratios. Subsequently, macromolecules on silica NPs originating from the copolymerization of growing PS or PVBA chains with the surface-grafted MMS compatibilizer are engineered by fine-tuning of polymer compositions or adjustment of solvent qualities. Moreover, multistage silica regrowth of tripod and tetrapod allowed a fine control of the patch-to-particle size ratio ranging from 0.69 to 1.54. Intriguingly, patchy silica NPs (1-, 2-, 3-PSNs) rather than hybrid clusters are successfully used as templates for multistep regrowth experiments, leading to the formation of silica NPs with a new morphology and size controllable PVBA/PS patches. Last but not least, combined with mesoscale dynamics simulations, the self-assembly kinetics of 2-PSN and 3-PSN into linear colloidal polymers and honeycomb-like lattices are studied. This work paves a new avenue for constructing colloidal polymers with a well-defined sequence and colloidal crystals with a predetermined architecture.

Defect transition of smectic liquid crystals confined in spherical cavities.

The formation and transformation of defects in confined liquid crystals are fascinating fundamental problems in soft matter. Here, we use molecular dynamics (MD) simulations to study ellipsoidal liquid crystals (LCs) confined in a spherical cavity, which significantly affects the orientation and translation of LC molecules near the surface. The liquid-crystal droplet can present the isotropic to smectic-B phase transition through the smectic-A phase, as the number density of the LC molecules increases. We further find the change of LC structure from bipolar to watermelon-striped during the phase transition from smectic-A (SmA) to smectic-B (SmB) phases. Our results reveal the transition from bipolar defects to the inhomogeneous structures with the coexistence of nematic and smectic phases in smectic liquid-crystal droplets. We also study the influence of the sphere size in the range of 10σ0 ≤ Rsphere ≤ 50σ0 on the structural inhomogeneities. It shows a weak dependence on the sphere size. We further focus on how the structures can be affected by the interaction strength εGB-LJ. Interestingly, we find the watermelon-striped structure can be changed into a configuration with four defects at the vertices of a tetrahedron upon increasing the interaction strength. The liquid crystals at a strong interaction strength of εGB-LJ = 10.0ε0 show the two-dimensional nematic phase at the surface. We further present an explanation for the origin of the striped-pattern formation. Our results highlight the potential for using confinement to control these defects and their associated nanostructural heterogeneity.

Helical structures of achiral liquid crystals under cylindrical confinement.

Confined liquid crystals (LCs) exhibit complex and intriguing structures, which are fascinating fundamental problems in soft matter. The helical structure of cylindrical cavities is of great importance in LC studies, particularly for their application in optical devices. In this study, we employ molecular dynamics simulations to explore the behavior of achiral smectic-B LCs confined in narrow cylindrical cavities, where geometric frustration plays an important role. By increasing the cylinder size, LCs exhibit a transition from multi-helical to layered structures. Notably, we observe two stable structures, namely the helical structure and the layered structure, at moderate cylinder size. We also investigate the effects of the arrangement of cylindrical wall particles (hexagonal or square array) and anchoring strength on the LC structure. Our findings reveal that both the hexagonal array and strong anchoring strength promote the formation of helical structures. Our study provides novel insights into the confinement physics of LCs and highlights the potential for achieving helical structures in achiral LCs, which will expand the future applications of LCs.

External field induced defect transformation in circular confined Gay-Berne liquid crystals.

Normally, defects in two-dimensional, circular, confined liquid crystals can be classified into four types based on the position of singularities formed by liquid crystal molecules, i.e., the singularities located inside the circle, at the boundary, outside the circle, and outside the circle at infinity. However, it is considered difficult for small aspect ratio liquid crystals to generate all these four types of defects. In this study, we use molecular dynamics simulation to investigate the defect formed in Gay-Berne, ellipsoidal liquid crystals, with small aspect ratios confined in a circular cavity. As expected, we only find two types of defects (inside the circle and at the boundary) in circular, confined, Gay-Berne ellipsoids under static conditions at various densities, aspect ratios, and interactions between the wall and liquid crystals. However, when introducing an external field to the system, four types of defects can be observed. With increasing the strength of the external field, the singularities in the circular, confined system change from the inside to the boundary and the outside, and the farthest position that the singularities can reach depends on the strength of the external field. We further introduce an alternating, triangular wave, external field to the system to check if we can observe the transformation of different defects within an oscillating period. We find that the position of the singularities greatly depends on the oscillating intensity and oscillating period. By changing the oscillating intensity and oscillating period of the external field, the defect types can be adjusted, and the transformation between different defects can be easily observed. This provides a feasible way to modulate liquid crystal defects and investigate the transformation between different defects.

Exploring mechanical properties and failure mechanisms of aramid and PBO crystals through molecular dynamics simulations.

Molecular dynamics simulations were used to analyze the mechanical properties and failure processes of poly(p-phenylene-terephthalamide) (PPTA), poly(p-phenylene-benzimidazole-terephthalamide) (PBIA), PBIA-PPTA (formed by 1:1 copolymerization of PPTA and PBIA), and poly(p-phenylene-benzobisoxazole) (PBO) crystals at different strain rates and temperatures. The failure stress and strain were found to be linear with the temperature and logarithmic strain rate. Moreover, based on the kinetic theory of fracture and the comprehensive simulation results, we formulated a model that describes the failure stress of the aforementioned crystals under varying strain rates and temperatures. Through the analysis of the failure process, we found that in PPTA, PBIA, and PBIA-PPTA crystals, the bond failure probability is correlated with the strain rate and temperature. The examination of bond lengths and angles unveiled that bonds with larger initial aligning angles are more susceptible to failure during the strain process. Intriguingly, the stretching process induced a conformational change in the PBO molecular chain, leading to a deviation from the linear relation in its stress-strain curve.

Cloning and functional study of GmRPI2, which is the critical gene of photosynthesis in soybean.

Light provides energy for photosynthesis and is also an important environmental signal that regulates plant growth and development. Ribose-5-phosphate isomerase plays a crucial role in photosynthesis. However, ribose-5-phosphate isomerase has yet to be studied in soybean photosynthesis. To understand the biological function of GmRPI2, in this study, GmRPI2 was cloned, plant overexpression vectors and gene editing vectors were successfully constructed, and transformed into recipient soybean JN74 using the Agrobacterium-mediated method. Using qRT-PCR, we analyzed that GmRPI2 gene expression was highest in leaves, second highest in roots, and lowest in stems. Promoter analysis revealed the presence of multiple cis-acting elements related to light response in the promoter region of GmRPI2. Compared with the control soybean plants, the net photosynthetic rate and transpiration rate of the overexpression lines were higher than those of the control and gene editing lines, while the intercellular CO2 concentration was significantly lower than that of the control and gene editing lines; the total chlorophyll, chlorophyll a, chlorophyll b contents and soluble sugar contents of the overexpression plants were significantly higher than those of the recipient and editing plants, indicating that the GmRPI2 gene can increase The GmRPI2 gene can increase the photosynthetic capacity of soybean plants, providing a theoretical basis and genetic resources for improving soybean yield by regulating photosynthetic efficiency.

Immobilization of Actinobacillus succinogenes on nano- and micro-fiber membranes for efficient and robust production of succinic acid.

This work aimed to study the efficiency of nano- and micro- fiber membranes in immobilizing Actinobacillus succinogenes CCTCC M2012036 for succinic acid production. Among the four kinds of electrospun nanofiber membranes of cellulose acetate, chitosan, poly(vinyl alcohol) (PVA) and chitosan-PVA, the cellulose acetate nanofiber membrane-immobilized cells performed the best with a succinic acid concentration and yield to be 27.3 ± 3.5 g/L and 70.9 ± 5.8%. The cell-immobilized viscose microfiber membrane presented good reuse stability, and 17 batches of fermentation without activity loss were realized with the highest succinic acid yield of 83.20%. A microfiber membrane bioreactor was further constructed with the cell-immobilized viscose microfiber membrane to perform fermentation on a larger scale, and the concentration, yield and productivity of succinic acid were 73.20 g/L, 86.50% and 1.49 g/(L⋅h) using a fed-batch strategy, which were 124.30%, 127.60% and 124.2% of those obtained in the traditional fermenter. This study provided an approach for improving the practicality of biological succinic acid production.

Colloidal cubic diamond photonic crystals through cooperative self-assembly.

Colloidal cubic diamond crystals with low-coordinated and staggered structures could display a wide photonic bandgap at low refractive index contrasts, which makes them extremely valuable for photonic applications. However, self-assembly of cubic diamond crystals using simple colloidal building blocks is still considerably challenging, due to their low packing fraction and mechanical instability. Here we propose a new strategy for constructing colloidal cubic diamond crystals through cooperative self-assembly of surface-anisotropic triblock Janus colloids and isotropic colloidal spheres into superlattices. In self-assembly, cooperativity is achieved by tuning the interaction and particle size ratio of colloidal building blocks. The pyrochlore lattice formed by self-assembly of triblock Janus colloids acts as a soft template to direct the packing of colloidal spheres into cubic diamond lattices. Numerical simulations show that this cooperative self-assembly strategy works well in a large range of particle size ratio of these two species. Moreover, photonic band structure calculations reveal that the resulting cubic diamond lattices exhibit wide and complete photonic bandgaps and the width and frequency of the bandgaps can also be easily adjusted by tuning the particle size ratio. Our work will open up a promising avenue toward photonic bandgap materials by cooperative self-assembly employing surface-anisotropic Janus or patchy colloids as a soft template.

A chiral smectic phase induced by an alternating external field.

Using simple achiral building blocks modulated by an external field to achieve chiral liquid crystal phases remains a challenge. In this study, a chiral helix liquid crystal phase is obtained for a simple Gay-Berne ellipsoid model under an alternating external field by using molecular dynamics simulations. Our results show that the chiral helix liquid crystal phase can be observed in a wide range of external field strengths when the oscillation period is smaller than the rotational characteristic diffusion timescale of ellipsoids. In addition, we find that the pitch and tilt angle of the helix structure can also be adjusted by changing the strength and oscillation period of the applied alternating external field. This may provide a feasible route for the regulation of chiral liquid crystal phases by an alternating external field.

Multiple 2D crystal structures in bilayered lamellae from the direct self-assembly of 3D systems of soft Janus particles.

Numerous crystals and Frank-Kasper phases in two-dimensional (2D) systems of soft particles have been presented by theoretical investigations. How to realize 2D crystals or Frank-Kasper phases via the direct self-assembly of three-dimensional (3D) systems remains an important issue. Here, through numerical simulations, we report the surprising finding of multiple 2D crystal structures in bilayered lamellae from the direct self-assembly of 3D systems of soft Janus particles. With varying the patch size and particle density, soft Janus particles, which exhibit very similar self-assembly behavior to giant amphiphiles, spontaneously form ordered bilayered lamellae. Within each layer of the bilayered lamellae, we find abundant highly-ordered 2D crystals including the Frank-Kasper σ phase and open kagome lattice. The kinetic mechanisms of the formation of these 2D crystals within the layers are revealed, and include a classical one-step nucleation mechanism and a two-step nucleation mechanism. Our findings suggest a simple route towards 2D crystals via the direct self-assembly of 3D systems of amphiphilic Janus building blocks.

Research progress in targeted therapies for gastric cancer.

Patients with advanced gastric cancer experience rapid disease progression with limited survival, high mortality, and a lack of surgical options. Thus, radiochemotherapy or a combination of chemotherapeutics with targeted therapy is the mainstay of treatment. In comparison to the treatment of other malignant tumors, in gastric cancer, the development of molecularly targeted drugs has been relatively slow. Currently, there are two major classes of molecularly targeted drug regimens that have achieved a certain efficacy in clinical practice: anti-vascular endothelial growth factor (anti-VEGF) therapy and anti-epidermal growth factor receptor (anti-EGFR) therapy. Trastuzumab has been approved as the standard of care for first-line treatment in advanced human epidermal growth factor receptor 2 (HER2)-positive gastric cancer. Ramucirumab in combination with paclitaxel is the recommended regimen for second-line treatment, and apatinib is recommended as third-line treatment. This review summarizes the current status of targeted therapies in the treatment of gastric cancer and gives a perspective on the future.

A Ligand-Directed Spatial Regulation to Structural and Functional Tunability in Aggregation-Induced Emission Luminogen-Functionalized Organic-Inorganic Nanoassemblies.

Aggregation-induced emission luminogen (AIEgen)-functionalized organic-inorganic hybrid nanoparticles (OINPs) are an emerging category of multifunctional nanomaterials with vast potential applications. The spatial arrangement and positioning of AIEgens and inorganic compounds in AIEgen-functionalized OINPs determine the structures, properties, and functionalities of the self-assembled nanomaterials. In this work, a facile and general emulsion self-assembly tactic for synthesizing well-defined AIEgen-functionalized OINPs is proposed by coassembling alkane chain-functionalized inorganic nanoparticles with hydrophobic organic AIEgens. As a proof of concept, the self-assembly and structural evolution of plasmonic-fluorescent hybrid nanoparticles (PFNPs) from concentric circle to core shell and then to Janus structures is demonstrated by using alkane chain-modified AuNPs and AIEgens as building blocks. The spatial position of AuNPs in the signal nanocomposite is controlled by varying the alkane ligand length and density on the AuNP surface. The mechanism behind the formation of various PFNP nanostructures is also elucidated through experiments and theoretical simulation. The obtained PFNPs with diverse structures exhibit spatially tunable optical and photothermal properties for advanced applications in multicolor and multimode immunolabeling and photothermal sterilization. This work presents an innovative synthetic approach of constructing AIEgen-functionalized OINPs with diverse structures, compositions, and functionalities, thereby championing the progressive development of these OINPs.

A Comprehensive Appraisal of Meta-Analyses of Exercise-Based Stroke Rehabilitation with Trial Sequential Analysis.

Meta-analysis is a common technique used to synthesise the results of multiple studies through the combination of effect size estimates and testing statistics. Numerous meta-analyses have investigated the efficacy of exercise programmes for stroke rehabilitation. However, meta-analyses may also report false-positive results because of insufficient information or random errors. Trial sequential analysis (TSA) is an advanced technique for calculating the required information size (RIS) and more restrictive statistical significance levels for the precise assessment of any specific treatment. This study used TSA to examine whether published meta-analyses in the field of stroke rehabilitation reached the RIS and whether their overall effect sizes were sufficient. A comprehensive search of six electronic databases for articles published before May 2022 was conducted. The intervention methods were divided into four primary groups, namely aerobic or resistance exercise, machine-assisted exercise, task-oriented exercise, and theory-based exercise. The primary outcome measure was gait speed and the secondary outcome measure was balance function. The data were obtained either from the meta-analyses or as raw data from the original cited texts. All data analysis was performed in TSA software. In total, 38 articles with 46 analysable results were included in the TSA. Only 17 results (37.0%) reached the RIS. In conclusion, meta-analysis interpretation is challenging. Clinicians must consider the RIS of meta-analyses before applying the results in real-world situations. TSA can provide accurate evaluations of treatment effects, which is crucial to the development of evidence-based medicine.

A highly selective 2''-O-glycosyltransferase from Ziziphus jujuba and De novo biosynthesis of isovitexin 2''-O-glucoside.

A novel and efficient 2''-O-glycosyltransferase ZjOGT38 was identified from Ziziphus jujuba. It could regio-selectively glycosylate 2-hydroxyflavanone C-glycosides. ZjOGT38 allowed de novo biosynthesis of isovitexin 2''-O-glucoside in E. coli.

A new xanthone from Halenia elliptica D. Don.

A new xanthone, 1,5-dihydroxy-2,3,4-trimethoxyxanthone (1), together with 15 known compounds (2-16), was isolated from an ethanolic extract of Halenia elliptica D. Don. Their structures were elucidated by spectroscopic methods. Among the known compounds, the (13)C NMR spectroscopic data of 2,3,4,5-tetramethoxyxanthone-1-O-gentiobioside (2) were reported for the first time.

Transition kinetics of defect patterns in confined two-dimensional smectic liquid crystals.

Topological defects in liquid crystals under confined geometries have attracted extensive research interests. Here, we perform molecular dynamics simulations to investigate the formation and transition of defect patterns in two-dimensional smectic Gay-Berne liquid crystals with a simple rectangular confinement boundary. Two typical types of defect patterns, bridge and diagonal defect patterns, are observed, which can be transformable continuously between each other over time. The transition usually starts from the line or point defect regions, and the competition between neighboring and opposite boundary effects induces the continuous realignments of the smectic layers to connect the neighboring or opposite walls. The relative stability of these two defect patterns can be controlled by changing the confinement conditions. These results deepen our understanding of transition kinetics of defect patterns in confined liquid crystals.

Softness-Enhanced Self-Assembly of Pyrochlore- and Perovskite-like Colloidal Photonic Crystals from Triblock Janus Particles.

It remains extremely challenging to build three-dimensional photonic crystals with complete photonic bandgaps by simple and experimentally realizable colloidal building blocks. Here, we demonstrate that particle softness can enhance both the self-assembly of pyrochlore- and perovskite-like lattice structures from simple deformable triblock Janus colloids and their photonic bandgap performances. Dynamics simulation results show that the region of stability of pyrochlore lattices can be greatly expanded by appropriately increasing softness, and the perovskite lattices are unexpectedly obtained at enough high softness. Photonic calculations show that the direct pyrochlore lattices formed from overlapping soft triblock Janus particles exhibit even larger photonic bandgaps than the ideal nonoverlapping pyrochlore lattice, and proper overlap arising from softness can also dramatically improve the photonic properties of the inverse pyrochlore and perovskite lattices. Our study offers a new and feasible self-assembly path toward three-dimensional photonic crystals with large and robust photonic bandgaps.

Intercluster Exchange-Stabilized Novel Complex Colloidal χc Phase.

Designing complex cluster crystals with a specific function using simple colloidal building blocks remains a challenge in materials science. Herein, we propose a conceptually new design strategy for constructing complex cluster crystals via hierarchical self-assembly of simple soft Janus colloids. A novel and previously unreported colloidal cluster-χ (χc) phase, which resembles the essential structural features of α-manganese but at a larger length scale, is obtained through molecular dynamics simulations. The formation of the χc phase undergoes a remarkable two-step self-assembly process, that is, the self-assembly of clusters with specific size dispersity from Janus colloids, followed by the highly ordered organization of these clusters. More importantly, the dynamic exchange of particles between these clusters plays a critical role in stabilizing the χc phase. Such a conceptual design framework based on intercluster exchange has the potential to effectively construct novel complex cluster crystals by hierarchical self-assembly of colloidal building blocks.

Methoxychalcone induces cell-cycle arrest and apoptosis in human hormone-resistant prostate cancer cells through PI 3-kinase-independent inhibition of mTOR pathways.

BACKGROUND: Chalcones are contained in fruits and vegetables, and have been suggested to display anticancer activities. In this study, the anticancer mechanism of WJ9708011 (a methoxychalcone derivative) was delineated in human prostate cancer cells. METHOD: Cell proliferation was examined by sulforhodamine B and clonogenic assays. Cell-cycle progression and mitochondrial membrane potential (DeltaPsi(m)) were detected by flow cytometric analysis. Expressions of protein and mRNA were detected by Western blot and RT-PCR technique, respectively. The protein synthesis was examined by [(3)H]leucine incorporation assay. The overexpression or knockdown techniques for specific target protein were also used in this study. RESULTS: WJ9708011 induced time- and concentration-dependent G1 arrest of the cell cycle and subsequent apoptosis in human prostate cancer cells. The G1-arrest effect was confirmed by down-regulated expressions of several G1-phase regulators, including cyclin D1, cyclin E, cyclin-dependent kinase (Cdk)-4, Cdk2, phospho-RB, E2F-1, and Cdc25A. The mRNA expressions of cyclin D1 and cyclin E were also inhibited through the suppression of NF-kappaB. WJ9708011 blocked the protein synthesis and inhibited mammalian target of rapamycin (mTOR) signaling pathways. The suppression of mTOR pathways were irrespective of Akt- and AMPK-activated protein kinase (AMPK), but were attributed to mitochondrial stress, in which the down-regulation of survivin protein level may play a crucial role. CONCLUSIONS: The data suggest that WJ9708011 induces transcriptional and translational suppression of cell-cycle regulators that might be through Akt- and AMPK-independent loss of DeltaPsi(m) and inhibition of mTOR signaling pathway, leading to G1 arrest of the cell cycle and subsequent apoptotic cell death.

Kinetics-controlled design principles for two-dimensional open lattices using atom-mimicking patchy particles.

The design and discovery of new two-dimensional materials with desired structures and properties are always one of the most fundamental goals in materials science. Here we present an atom-mimicking design concept to achieve direct self-assembly of two-dimensional low-coordinated open lattices using three-dimensional patchy particle systems. Besides honeycomb lattices, a new type of two-dimensional square-octagon lattice is obtained through rational design of the patch configuration of soft three-patch particles. However, unexpectedly the building blocks with thermodynamically favoured patch configuration cannot form square-octagon lattices in our simulations. We further reveal the kinetic mechanisms controlling the formation of the honeycomb and square-octagon lattices. The results indicate that the kinetically favoured intermediates play a critical role in determining the structure of obtained open lattices. This kinetics-controlled design principle provides a particularly effective and extendable framework to construct other novel open lattice structures.