Rapid and Visual Detection of Volatile Amines Based on Their Gas-Solid Reaction with Tetrachloro-p-Benzoquinone.

The detection of volatile amines is necessary due to the serious toxicity hazards they pose to human skin, respiratory systems, and nervous systems. However, traditional amines detection methods require bulky equipment, high costs, and complex measurements. Herein, we report a new simple, rapid, convenient, and visual method for the detection of volatile amines based on the gas-solid reactions of tetrachloro-p-benzoquinone (TCBQ) and volatile amines. The gas-solid reactions of TCBQ with a variety of volatile amines showed a visually distinct color in a time-dependent manner. Moreover, TCBQ can be easily fabricated into simple and flexible rapid test strips for detecting and distinguishing n-propylamine from other volatile amines, including ethylamine, n-butyamine, n-pentamine, n-butyamine and dimethylamine, in less than 3 s without any equipment assistance.

Keto-Adamantane-Based Macrocycle Crystalline Supramolecular Assemblies Showing Selective Vapochromism to Tetrahydrofuran.

Here, we report the synthesis of adamantane-based macrocycle 2 by combining adamantane building blocks with π-donor 1,3-dimethoxy-benzene units. An unpredictable keto-adamantane-based macrocycle 3 was obtained by the oxidation of 2 using DDQ as an oxidant. Moreover, a new type of macrocyclic molecule-based CT cocrystal was prepared through exo-wall CT interactions between 3 and DDQ. The cocrystal material showed selective vapochromism behavior towards THF, specifically, among nine volatile organic solvents commonly used in the laboratory. Powder X-ray diffraction; UV-Vis diffuse reflectance spectroscopy; 1H NMR; and single crystal X-ray diffraction analyses revealed that color changes are attributed to the vapor-triggered decomplexation of cocrystals.

Giant Cavity Macrocycle: Synthesis, Structure, and Its Complexation with Pagoda[5]arene.

A novel stretched hexagon structure naphthalene diimides-extended-pillar[6]arene 1 with a giant cavity size of 18.769 Å in width and 17.109 Å in height is reported. 1 exhibits highly selective binding of pagoda[5]arene compared to pillar[5]arene and prism[5]arene. Size matching and charge transfer interactions play a key role in the formation of the ring-in-ring stable complex.

Binaphthyl-Based Chiral Macrocyclic Hosts for the Selective Recognition of Iodide Anions.

In this study, we explorethe synthesis of binaphthyl-based chiral macrocyclic hosts for the first time. They exhibited the selective recognition abilities of iodide anions which can be favored over those of other anions (AcO-, NO3-, ClO4-, HSO4-, Br-, PF6-, H2PO4-, BF4-, and CO3F3S-), as confirmed by UV-vis, HRMS, and 1H NMR spectroscopy experiments, as well as DFT calculations. Neutral aryl C-H···anion interactions play an important role in the formation complexes. The recognition process can be observed by the naked eye.

Water soluble macrocyclic host for recognition of N-methylquinolinium salts in water.

In this paper, we reported the synthesis of water soluble macrocyclic arenes 1 containing anionic carboxylate groups. It was found that host 1 could form a 1 : 1 complex with N-methylquinolinium salts in water. Moreover, the complexation and decomplexation of the complexes between host and the guests could be achieved by changing the pH of the solution, and the process could also be observed by naked eye.

A gene silencing screen uncovers diverse tools for targeted gene repression in Arabidopsis.

DNA methylation has been utilized for target gene silencing in plants. However, it is not well understood whether other silencing pathways can be also used to manipulate gene expression. Here we performed a gain-of-function screen for proteins that could silence a target gene when fused to an artificial zinc finger. We uncovered many proteins that suppressed gene expression through DNA methylation, histone H3K27me3 deposition, H3K4me3 demethylation, histone deacetylation, inhibition of RNA polymerase II transcription elongation or Ser-5 dephosphorylation. These proteins also silenced many other genes with different efficacies, and a machine learning model could accurately predict the efficacy of each silencer on the basis of various chromatin features of the target loci. Furthermore, some proteins were also able to target gene silencing when used in a dCas9-SunTag system. These results provide a more comprehensive understanding of epigenetic regulatory pathways in plants and provide an armament of tools for targeted gene manipulation.

A Benzothiadiazole-Based Self-Assembled Cage for Cadmium Detection.

A turn-on fluorescent probe, cage 1, was efficiently self-assembled by condensing 4,4'-(benzothiadiazole-4,7-diyl)dibenzaldehyde and TREN in chloroform. The formation of cage 1 was characterized and confirmed by NMR spectroscopy, mass spectrometry, and theoretical calculations. The yield of cage 1 could be controlled by tuning the reaction conditions, such as the precursor concentration. Interestingly, the addition of 10 equiv of Cd2+ relative to cage 1 could increase the fluorescence almost seven-fold. 1H NMR and fluorescence experiments indicating fluorescence enhancement may be caused by the decomposition of cage 1. Such a high selectivity toward Cd2+ implies that the cage could potentially be employed in cadmium detection.

Adsorptive separation of para-xylene by nonporous adaptive crystals of phenanthrene[2]arene.

In this work, we developed a new method for the preparation of phenanthrene[2]arene on a large-scale. Meanwhile, the synthetic phenanthrene[2]arene has been successfully used as nonporous adaptive crystals for the separation of para-xylene (pX) from xylene isomers. The crystal structure revealed that one host molecule can adsorb one pX molecule to form the 1@pX complex, in which pX is located in the cavity of the host.

Pyromellitic Diimide-Extended Pillar[6]arene: Synthesis, Structure, and Its Complexation with Polycyclic Aromatic Hydrocarbons.

A novel pyromellitic diimide-extended pillar[6]arene was synthesized in two steps with moderate yield for the first time. It showed a symmetrical stretched hexagon structure and could form 1:2 complexes with polycyclic aromatic hydrocarbons in solution. Interestingly, a linear supramolecular array between complex 1@G42 and pyrene through π···π stacking interactions was also observed in the solid state.

Conditional estimation and inference to address observed covariate imbalance in randomized clinical trials.

BACKGROUND: Baseline covariate imbalance (between treatment groups) is a common problem in randomized clinical trials which often raises questions about the validity of trial results. Answering these questions requires careful consideration of the statistical implications of covariate imbalance. The possibil ity of having covariate imbalance contributes to the marginal variance of an unadjusted treatment difference estimator, which can be reduced by making appropriate adjustments. Actual observed imbalance introduces a conditional bias into an unadjusted estimator, which may increase the conditional size of an unadjusted test. METHODS: This article provides conditional estimation and inference procedures to address the conditional bias due to observed imbalance. Interestingly, it is possible to use the same adjusted treatment difference estimator to address the marginal variance issue and the conditional bias issue associated with covariate imbalance. Its marginal variance estimator tends to be conservative for conditional inference, and we propose a conditionally appropriate variance estimator. We also provide an estimator of the conditional bias in an unadjusted treatment difference estimator, together with a conditional variance estimator. RESULTS: The proposed methodology is illustrated with real data from a stroke trial and evaluated in simulation experiments based on the same trial. The simulation results show that covariate imbalance can result in a substantial conditional bias and that the proposed methods deal with the conditional bias quite effectively. DISCUSSION: We recommend that the proposed methodology be used routinely to address the observed covariate imbalance in randomized clinical trials.

One-pot synthesis of etched Cu2O cubes with exposed {110} facets with enhanced visible-light-driven photocatalytic activity.

Novel etched Cu2O cubes with exposed {110} facets are synthesized via an oxidative etching method at room temperature. The photocatalytic performance indicates that these architectures show higher photocatalytic activity than that of the normal Cu2O cubes in the degradation of methylene orange.

Sulfate-ion-assisted galvanic replacement tuning of silver dendrites to highly branched chains for effective SERS.

Morphology is a primary part of designing metal nanocrystals and nanomaterials with controlled functional properties. Here, we demonstrate the potential of foreign sulfate ions to tune the silver dendrites to highly branched chains through a simple galvanic replacement reaction without introducing any organic surfactants. We further illustrate the underlying mechanism according to diffusion-limited aggregation (DLA) in the presence of sulfate ions. The special aspects of this simple synthetic strategy are the control of both the nucleation process and the subsequent crystal growth stage by using sulfate ions as the ionic surfactants thereby tuning the total surface energies on various crystal facets in solution and transforming crystal growth habits of the products. Moreover, the highly branched silver chains (HBSCs) with pure surfaces have been successfully employed as a Raman probe for surface-enhanced Raman spectroscopic analysis of rhodamine 6G (R6G). The particular morphology of those HBSCs also makes them find potential applications in biosensing, catalysis and optics.

One-pot fabrication of novel cuboctahedral Cu2O crystals enclosed by anisotropic surfaces with enhancing catalytic performance.

For the first time, one-pot solution-phase selective-etching to create cuboctahedral Cu2O crystals enclosed by both stepped {111} surfaces and smooth {100} surfaces has been demonstrated. Investigation of photocatalytic performances indicates that the stepped cuboctahedral Cu2O crystals have higher photocatalytic activities than those of the common smooth ones.