Spatial heterogeneity of soil moisture caused by drainage and its effects on cadmium variation in rice grain within individual fields.

Paddy drainage is the critical period for rice grain to accumulate cadmium (Cd), however, its roles on spatial heterogeneity of grain Cd within individual fields are still unknown. Herein, field plot experiments were conducted to study the spatial variations of rice Cd under continuous and intermittent (drainage at the tillering or grain-filling or both stages) flooding conditions. The spatial heterogeneity of soil moisture and key factors involved in Cd mobilization during drainages were further investigated to explain grain Cd variation.

Catalytic polymerization of bisphenol A using a horseradish peroxidase immobilized microporous membrane reactor.

Bisphenol A (BPA) is one of the most widely used chemical products, which is discharged into rivers and oceans, posing great hazards to organisms such as reproductive toxicity, hormone imbalance and cardiopathy induction. With the expansion harm of BPA, people have paid more attention to the environmental effects. In this paper, the degradation of BPA from the synthetic wastewater using the immobilization of horseradish peroxidase membrane reactor (HPR) was investigated.

Enhanced CO Photoreduction through Spontaneous Charge Separation in End-Capping Assembly of Heterostructured Covalent-Organic Frameworks.

It is well known that charge separation is crucial for efficient photocatalytic solar conversion. Although some covalent-organic frameworks (COFs) exhibit visible-light harvest, the large exciton binding energies reduce their photocatalytic efficiencies. Herein, we developed a novel method to post-treat the olefin-linked COFs with end-capping polycyclic aromatic hydrocarbons (PAHs) for spontaneous charge separation.

Ultrasound-Induced Amino Acid-Based Hydrogels With Superior Mechanical Strength for Controllable Long-Term Release of Anti-Cercariae Drug.

Stimulus-responsive hydrogels are significantly programmable materials that show potential applications in the field of biomedicine and the environment. Ultrasound as a stimulus can induce the formation of hydrogels, which exhibit the superior performance of different structures. In this study, we reported an ultrasound-induced supramolecular hydrogel based on aspartic acid derivative ,'-diaspartate-3,4,9,10-perylene tetracarboxylic acid imide, showing superior performance in drug release.

Controlled Construction of an Exquisite Three-Component Co-assembly Supramolecular Structure at the Liquid-Solid Interface.

A three-component supramolecular co-assembly structure formed at the liquid-solid interface by employing a shape-persistent π-conjugated macrocycle (1) and two guest molecules (COR and C) is demonstrated. Scanning tunneling microscopy (STM) observations revealed that 1 can serve as a versatile host molecule that can co-assemble with both COR and C guest molecules to form stable two-component structures, where the COR guest molecule filled in the gap between the side chains of adjacent 1 molecules, and the C guest molecule entered the inner cavity of 1. It was found that the adding sequence of COR and C guest molecules is crucial to the resulting co-adsorption structure in the three-component system.

On-Surface Crystallization Behaviors of H-Bond Donor-Acceptor Complexes at Liquid/Solid Interfaces.

Two-dimensional (2D) crystallization behaviors of A-TPC ( n = 4, 6, 10), T3C, and hydrogen-bonded complexes T3C@TPC ( n = 4, 6, 10) are investigated by means of scanning tunneling microscope (STM) observations and density functional theory (DFT) calculations. The STM observations reveal that A-TPC, A-TPC, and T3C self-organize into dumbbell-shaped structures, well-ordered bright arrays, and zigzag structures, respectively. Interestingly, T3C@TPC fails to form the cage-ball structure, whereas T3C@TPC and T3C@TPC co-assemble into cage-ball structures with the same lattice parameters.

Temperature-Triggered Self-Assembled Structural Transformation: From Pure Hydrogen-Bonding Quadrilateral Nanonetwork to Trihexagonal Structures.

Adequate control over the structures of molecular building blocks plays an important role in the fabrication of desired supramolecular nanostructures at interfaces. In this study, the formation of a pure hydrogen-bonding co-assembly supramolecular nanonetwork on a highly oriented pyrolytic graphite surface was demonstrated by means of a scanning tunneling microscope. The thermal annealing process was conducted to monitor the temperature-triggered structural transformation of the self-assembled nanonetwork.

Ultrasensitive Detection of Serum MicroRNA Using Branched DNA-Based SERS Platform Combining Simultaneous Detection of α-Fetoprotein for Early Diagnosis of Liver Cancer.

We provided an ultrasensitive sensing strategy for microRNA detection by first employing branched DNA. With the aid of microcontact printing, we realized the multiplex sensing of different kinds of liver cancer biomarkers: microRNA and protein simultaneously. Delicately designed branched DNA included multiple complementary sticky ends as probe to microRNA capture and the double-stranded rigid branched core to increase the active sticky-ends distance and expose more DNA probes for sensitivity.

In Situ Monitoring the Aggregation Dynamics of Amyloid-β Protein Aβ42 in Physiological Media via a Raman-Based Frequency Shift Method.

Amyloid-β protein (Aβ) is a major biomarker candidate for the diagnosis of Alzheimer's disease (AD). It is known that the core segment of Aβ42 tends to aggregate into neurotoxic soluble oligomeric species and finally into fibrillar structures associated with AD; however, much remains to be learned about the conformational changes and dynamic aggregation processes of Aβ protein in solution. Herein we exploit the selectivity of affinity peptides, singled out by biopanning a phage display library, to recognize and capture Aβ42 and its fibers.

Frequency Shift Raman-Based Sensing of Serum MicroRNAs for Early Diagnosis and Discrimination of Primary Liver Cancers.

Frequency shift surface-enhanced Raman scattering (SERS) achieves multiplex microRNA sensing for early serological diagnosis of, and discrimination between, primary liver cancers in a patient cohort for whom only biopsy is effective clinically. Raman reporters microprinted on plasmonic substrates shift their vibrational frequencies upon biomarker binding with a dynamic range allowing direct, multiplex assay of serum microRNAs and the current best protein biomarker, α-fetoprotein. Benchmarking against current gold-standard polymerase chain reaction and chemiluminescence methods validates the assay.

Surface Separation and in Situ Structural Regulation of Photosensitive Oligomer in a Flexible Template.

Surface-selective adsorption and separation are very important for the application of surface functional materials. In this study, a photosensitive diazo-macrocycle has been synthesized by the solvent method with a very low yield, which can adsorb onto the substrate surface modified with a template molecule. By using this flexible template on the graphite surface, a simple separation strategy for the macrocyclic molecule with specific shape and size from reaction mixtures was developed.

Formation and Controlled Drug Release Using a Three-Component Supramolecular Hydrogel for Anti- Cercariae.

A novel three-component supramolecular hydrogel based on riboflavin, melamine and amino acid derivatives were constructed for controlled release of pesticides, Niclosamide derivatives. The formation of hydrogel may be attributed to self-assemble via hydrogen bonding and π-π interaction, which have been researched via scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectra. The rheological experiments showed that the hydrogel materials and drug-loaded hydrogel all demonstrated good mechanical strength and high stability.

Temperature-Triggered Chiral Self-Assembly of Achiral Molecules at the Liquid-Solid Interface.

Temperature triggered chiral nanostructures have been investigated on two-dimensional (2D) surfaces by means of scanning tunneling microscopy. Achiral molecules 1 and 2 tend to self-assemble into strip structures on graphite before heating. However, R and S flower-like structures are observed when heated to certain temperature.

A Smart pH-Responsive Three Components Luminescent Hydrogel.

In this study, we report a novel three-component luminescent hydrogel, which is composed of amino acid derivatives (N,N'-di valine-3,4,9,10-perylenetetracarboxylic acid, NVPD), riboflavin (RF), and melamine (MM). The three-component hydrogel is attributed to multiple hydrogen bonds and the strong π-π stacking interaction between these molecules. Based on the strong hydrogen bonding of the gelator, when the reversible process between the gel and the solution take places it changes the pH of the system from 6.

On-Surface Observation of the Formation of Organometallic Complex in a Supramolecular Network.

The on-surface formation of organometallic monomers or oligomers, especially in supramolecular network, attracts an extensive interest for chemists and material scientist. In this work, we have investigated metal coordination between zinc (II) phthalocyanine (ZnPc) and 1, 3-di (4-pyridyl) propane (dipy-pra) in the 2, 6, 11-tricarboxydecyloxy-3, 7, 10-triundecyloxy triphenylene (asym-TTT) supramolecular template by means of scanning tunneling microscopy (STM) on highly oriented pyrolytic graphite (HOPG) substrate under ambient conditions. The experimental results demonstrate that every two ZnPc molecules in one nano-reactor connect with each other through one dipy-pra molecule by metal-coordination interaction.

Hierarchical self-assembly of amino acid derivatives into stimuli-responsive luminescent gels.

In this study, unique luminescent gels have been obtained from two components between amino acid functionalized perylene derivatives and 4,4'-bipyridyl units via hierarchical self-assembly. The luminescent gels have been investigated by means of ultraviolet spectra (UV), fluorescence spectra, Scanning Electron Microscopy (SEM) and Laser Scanning Confocal Microscopy (LSCM), which illustrate the strong fluorescence intensity of the gels. In order to further reveal the self-assembly driving forces, the two-dimensional (2D) self-assembly behaviours have been studied by scanning tunneling microscopy (STM) on a highly oriented pyrolytic graphite (HOPG) substrate at the solid-liquid interface, which indicates that the driving forces are attributed to the intermolecular hydrogen bonding and π-π stacking interactions.