Tuning of the Electrostatic Potentials on the Surface of the Sulfur Atom in Organic Molecules: Theoretical Design and Experimental Assessment.

Noncovalent sulfur interactions are ubiquitous and play important roles in medicinal chemistry and organic optoelectronic materials. Quantum chemical calculations predicted that the electrostatic potentials on the surface of the sulfur atom in organic molecules could be tuned through the through-space effects of suitable substituents. This makes it possible to design different types of noncovalent sulfur interactions.

Simulated Gastric Acid Promotes the Horizontal Transfer of Multidrug Resistance Genes across Bacteria in the Gastrointestinal Tract at Elevated pH Levels.

The assessment of factors that can promote the transmission of antibiotic resistance genes (ARGs) across bacteria in the gastrointestinal tract is in great demand to understand the occurrence of infections related to antibiotic-resistant bacteria (ARB) in humans. However, whether acid-resistant enteric bacteria can promote ARG transmission in gastric fluid under high-pH conditions remains unknown. This study assessed the effects of simulated gastric fluid (SGF) at different pH levels on the RP4 plasmid-mediated conjugative transfer of ARGs.

Visual Detection of using Combined CRISPR/Cas12a and Recombinase Polymerase Amplification.

Objective: To establish an ultra-sensitive, ultra-fast, visible detection method for (VP)

Methods: We established a new method for detecting the and genes of VP using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 12a (CRISPR/Cas12a) combined with recombinase polymerase amplification and visual detection (CRISPR/Cas12a-VD).

Results: CRISPR/Cas12a-VD accurately detected target DNA at concentrations as low as 10 M (single molecule detection) within 30 min without cross-reactivity against other bacteria. When detecting pure cultures of VP, the consistency of results reached 100% compared with real-time PCR.

Spatial behavior and source tracking of extracellular antibiotic resistance genes in a chlorinated drinking water distribution system.

Antibiotic resistance genes (ARGs) are receiving increasing concerns due to the antibiotic resistance crisis. Nevertheless, little is known about the spatial behavior and sources of extracellular ARGs (eARGs) in the chlorinated drinking water distribution systems (DWDSs). Here, tap water was continuously collected to reveal the occurrence of both eARGs and intracellular ARGs (iARGs) along a chlorinated DWDS.

[Effects of Chlorine Dioxide Disinfection on the Profile of the Super Antibiotic Resistance Genes in a Wastewater Treatment Plant].

In order to study the effects of chlorine dioxide (ClO) disinfection on the super antibiotic resistance genes (SARGs), the final effluents before and after chlorine dioxide were sampled throughout one year in a wastewater treatment plant (WWTP). The bacteria and extracellular nucleic acid were collected using microporous membrane filtration and nucleic acid adsorption particles, respectively. A total of 9 SARGs was detected through a quantitative real-time polymerase chain reaction (qPCR).

[Simultaneous determination of three antidepressant drugs in feces by HLPC-MS].

To establish a high performance liquid chromatography tandem mass spectrometry (HPLC / MS) method for the simultaneous determination of three antidepressant drugs in feces. Samples were pretreated with n-hexane isopropanol (95:5, v/v). Gradient elution was carried out with mixed liquid of ultrapure water and acetonitrile as mobile phase and separated by Agilent ZORBAX SB-C18 liquid chromatography column (2.

Decreased Antibiotic Susceptibility in Surviving UV Irradition.

Given its excellent performance against the pathogens, UV disinfection has been applied broadly in different fields. However, only limited studies have comprehensively investigated the response of bacteria surviving UV irradiation to the environmental antibiotic stress. Here, we investigated the antibiotic susceptibility of suffering from the UV irradiation.

ESIPT fluorophores derived from 2,3-dichloro-5,6-dicyano--benzoquinone based carbon dots for dual emission and multiple anti-counterfeiting.

Fluorophores and hydrogen bonding interactions play key roles in the fluorescence properties of bottom-up carbon dots. In this work, an excited-state intramolecular proton-transfer (ESIPT) active fluorophore, 5-chloro-6-ethoxy-4,7-dihydroxyisoindoline-1,3-dione (CEDD) and a non-ESIPT 7-cyano-5,8-dihydroxyquinoxaline-6-carboxamide (CDQC) are extracted from 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) based carbon dots. The enol form of CEDD shows a weak blue, small Stokes shift and short lifetime emission under the aprotic or alkali conditions, but the keto form exhibits a strong green, large Stokes shift and long lifetime emission in a protic or an acidic environment.

Noncovalently Fused-Ring Electron Acceptors with Symmetry for Regulating the Morphology of Organic Solar Cells.

Four noncovalently fused-ring electron acceptors -DOC6-2F, -DOC6-2F, -DOC8-2F, and -DOC2C6-2F have been designed and synthesized. -DOC6-2F and -DOC6-2F have the same molecular backbone but different molecular shapes and symmetries. -DOC6-2F has an S-shaped molecular backbone and symmetry, whereas -DOC6-2F possesses a U-shaped molecular backbone and symmetry.

Contamination sources of the enteric virus in recreational marine water shift in a seasonal pattern.

Human enteric virus occurrence in bathing beaches poses a potential health risk to swimmers. They may come from several sources, but the understanding of the seasonal contribution of contamination sources to virus occurrence is still lacking. Here, the surveillance of human enteric viruses at the First Bathing Beach in Qingdao was performed January-December 2018.

Chlorine disinfection promotes the exchange of antibiotic resistance genes across bacterial genera by natural transformation.

Chlorine disinfection to drinking water plays an important role in preventing and controlling waterborne disease outbreaks globally. Nevertheless, little is known about why it enriches the antibiotic resistance genes (ARGs) in bacteria after chlorination. Here, ARGs released from killed antibiotic-resistant bacteria (ARB), and culturable chlorine-injured bacteria produced in the chlorination process as the recipient, were investigated to determine their contribution to the horizontal transfer of ARGs during disinfection treatment.

Benzoquinone-Based Polyimide Derivatives as High-Capacity and Stable Organic Cathodes for Lithium-Ion Batteries.

Multicarbonyl polyimide derivatives were synthesized by a facial condensation polymerization of dianhydrides with a new diamine monomer containing a benzoquinone unit that was prepared according to the Michael addition reaction. The ingenious combination of dedicated carbonyl groups from the benzoquinone and dianhydride with an aniline structure linkage not only provided stable polymeric chains with a high number of carbonyl groups per unit but also guaranteed their large π-conjugated main chains, which is favorable to their long cycle life and fast kinetics. When explored as cathode materials for lithium-ion batteries, the polyimide derivatives based on naphthalic dianhydride delivered a reversible specific capacity of 145 mAh/g at 0.

Effects of Electronic Structure of Adjacent Carbon on the Strength of C─F⋯H─F Organofluorine Hydrogen Bonds.

We investigate the effects of the electronic structure of carbon atom on the organofluorine hydrogen bonds, C─F⋯H─F. Our results show that we can modulate the strength of organofluorine hydrogen bonds by adjusting the volume of fluorine atom in C─F via changing the electronic structure of adjacent carbon atoms. Different with the conventional hydrogen bonds, we found that instead of carbon rehybridization and hyperconjugative effects, the magnitude of fluorine atomic volume plays important roles in determining the strength of the C─F⋯H─F organofluorine hydrogen bonds.

Global exploration of potential energy surfaces for radical generation in the initial stage of benzene oxidation.

The potential energy surfaces (PESs) of benzene oxidation by molecular oxygen were explored using the anharmonic downward distortion following (ADDF) and artificial force induced reaction (AFIR) methods of the global reaction route mapping (GRRM) strategy. The reaction mechanism of benzene activation by initial molecular oxygen depends on the combustion temperature. At high temperature, the benzene molecule could be oxidized by abstracting hydrogen atoms and form the radical fragments, CH and OOH.

Tetrel Bond between 6-OTX₃-Fulvene and NH₃: Substituents and Aromaticity.

Carbon bonding is a weak interaction, particularly when a neutral molecule acts as an electron donor. Thus, there is an interesting question of how to enhance carbon bonding. In this paper, we found that the ⁻OCH₃ group at the exocyclic carbon of fulvene can form a moderate carbon bond with NH₃ with an interaction energy of about -10 kJ/mol.

Terpenoids from the roots of and their inhibitory activity on NO production in RAW264.7 cells.

Phytochemical investigation of the roots of , led to the isolation of a novel norsesquiterpene, named as longifolactone (), along with three known diterpenes. The structures of these compounds were elucidated by analysis of HR-ESI-MS, UV, IR and 1D and 2D NMR spectroscopic data. The absolute configuration of the new compound was determined by electronic circular dichroism (ECD) using both experimental and calculated ECD spectra.

Understanding the effects of vicinal carbon substituents and configuration on organofluorine hydrogen-bonding interaction.

An investigation of C-F⋯H-O hydrogen bonds in the complexes CH XCH F⋯HO ( = 0, 1, 2; X = H, F, Cl, Br) was performed at the MP2/aug-cc-pVTZ level. We found that the electron-withdrawing halogen substituents on the vicinal carbon cause the fluorine atom, participating in the hydrogen bond formation, to be less negatively charged. Thus, the halogen groups weaken the strength of organofluorine hydrogen bond by inductive effect.

Insight into the multiple quasi-molecular states in ethylenediamine reduced graphene nanodots.

Recently, graphene nanodots (GNDs) have been frequently considered as inherently heterogeneous systems, leading to multicolor emission under a changeable excitation wavelength. However, an accurate picture of the GNDs and an exhaustive structure-property correlation are still lacking. Using a two dimensional photoluminescence excitation (2D-PLE) map, molecular orbital calculation, reduction level dependent PL analysis, absorption spectroscopy and time-resolved PL spectroscopy, three cases of quasi-molecular PL are determined in ethylenediamine (EDA) reduced GNDs, including the C[double bond, length as m-dash]O related electronic state, graphenol related electronic state and large π-conjugated domains.

Tetrel bond of pseudohalide anions with XHF (X = C, Si, Ge, and Sn) and its role in S2 reaction.

The complexes of XHF⋯N/OCN/SCN (X = C, Si, Ge, and Sn) have been investigated at the MP2/aug-cc-pVTZ(PP) level. The σ-hole of X atom in XHF acts as a Lewis acid forming a tetrel bond with pseudohalide anions. Interaction energies of these complexes vary from -8 to -50 kcal/mol, mainly depending on the nature of X and pseudohalide anions.

Experimental and computational studies on molecularly imprinted solid-phase extraction for gonyautoxins 2,3 from dinoflagellate Alexandrium minutum.

An innovative and effective extraction procedure based on molecularly imprinted solid-phase extraction (MISPE) was developed for the isolation of gonyautoxins 2,3 (GTX2,3) from Alexandrium minutum sample. Molecularly imprinted polymer microspheres were prepared by suspension polymerization and and were employed as sorbents for the solid-phase extraction of GTX2,3. An off-line MISPE protocol was optimized.

[Research advances on medical genetics in China in 2015].

Steady progress has been achieved in the medical genetics in China in 2015, as numerous original researches were published in the world's leading journals. Chinese scientists have made significant contributions to various fields of medical genetics, such as pathogenicity of rare diseases, predisposition of common diseases, somatic mutations of cancer, new technologies and methods, disease-related microRNAs (miRNAs), disease-related long non-coding RNAs (lncRNAs), disease-related competing endogenous RNAs (ceRNAs), disease-related RNA splicing and molecular evolution. In these fields, Chinese scientists have gradually formed the tendency, from common variants to rare variants, from single omic analyses to multipleomics integration analyses, from genetic discovery to functional confirmation, from basic research to clinical application.

A photodegradable hexaaza-pentacene molecule for selective dispersion of large-diameter semiconducting carbon nanotubes.

Harvesting high-purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with removable dispersants remains a challenge. In this work, we demonstrate that small heteroacene derivatives may serve as promising selective dispersants for sorting s-SWCNTs. A rich N "doped" and thiophene-substituted hexaazapentacene molecule, denoted as 4HP, was found to be more favorable for high-purity s-SWCNTs with large diameters.

Origin of selenium-gold interaction in F2CSe⋯AuY (Y = CN, F, Cl, Br, OH, and CH3): Synergistic effects.

Selenium-gold interaction plays an important role in crystal materials, molecular self-assembly, and pharmacochemistry involving gold. In this paper, we unveiled the mechanism and nature of selenium-gold interaction by studying complexes F2CSe⋯AuY (Y = CN, F, Cl, Br, OH, and CH3). The results showed that the formation of selenium-gold interaction is mainly attributed to the charge transfer from the lone pair of Se atom to the Au-Y anti-bonding orbital.

Synthesis and Anticancer Activities of Glycyrrhetinic Acid Derivatives.

A total of forty novel glycyrrhetinic acid (GA) derivatives were designed and synthesized. The cytotoxic activity of the novel compounds was tested against two human breast cancer cell lines (MCF-7, MDA-MB-231) in vitro by the MTT method. The evaluation results revealed that, in comparison with GA, compound 42 shows the most promising anticancer activity (IC50 1.