pH dependence of reactive oxygen species generation and pollutant degradation in Fe(II)/O/tripolyphosphate system.

It has been reported that tripolyphosphate (TPP) can effectively enhance the activation of O by Fe(II) to remove organic pollutants in the environment. However, the influence of solution pH on the generation and conversion of reactive oxygen species (ROS) and their degradation of pollutants in the Fe(II)/O/TPP system needs further investigation. In this study, we demonstrated that O and •OH were the main ROS responsible for degradation in the system at different pH conditions, and their formation rates were calculated using a steady-state model.

Effect of Interfacial Action on the Generation and Transformation of Reactive Oxygen Species in Tripolyphosphate-Enhanced Heterogeneous FeO/O Systems.

It has been reported that tripolyphosphate (TPP) can enhance the oxygenation of natural Fe(II)-containing minerals to produce reactive oxygen species (ROS). However, the molecular structure of the TPP-Fe(II) mineral surface complex and the role of this complex in the generation and transformation of ROS have not been fully characterized. In the present study, a heterogeneous magnetite (FeO)/O/TPP system was developed for the degradation of p-nitrophenol (PNP).

Investigating the influence of substituent groups in TTM based radicals for the excitation process: a theoretical study.

Tri-(2,4,6-trichlorophenyl)methyl (TTM) based radicals can be promising in providing relatively high fluorescence quantum efficiency. In this study, we have evaluated the photoluminescence properties of a series of TTM-based radicals by means of DFT and TD-DFT methods. The optimized structures of the ground states (D) and the first excited states (D) of all the radicals are calculated and the computed emission bands are comparable with previous experimental results.

Design and bioanalytical applications of stochastic DNA walkers.

Synthetic DNA walkers that are inspired by the walking behaviors of naturally occurring motor proteins have emerged into an important subfield of DNA nanotechnology. While early DNA walkers were designed to walk on one-dimensional (1D) DNA tracks, the development of DNA origami and DNA functionalized micro-/nanomaterials has enabled diverse 2D and 3D tracks. Random walking becomes possible in such platforms and such stochastic DNA walkers can be engineered with much-improved speed and processivity.

Theoretical insight on the saturated stimulated emission intensity of a squaraine dye for STED nanoscopy.

Stimulated emission depletion nanoscopy (STED) is increasingly applied for the insights into the ultra-structures of organelles in live cells because of the bypassing of the Abbe's optical diffraction limit. Theoretically, with the increase of excitation and depletion laser power, the imaging resolution can be accordingly enhanced and even close to the infinity. Unfortunately, powerful laser illuminations usually produce severe phototoxicity and photobleaching, which will lead to more extra-interference with biological events in live cells and accelerate the decomposition of the fluorescent probes.

Stimuli-Responsive Three-Dimensional DNA Nanomachines Engineered by Controlling Dynamic Interactions at Biomolecule-Nanoparticle Interfaces.

Stimuli-responsive nanomachines are attractive tools for biosensing, imaging, and drug delivery. Herein, we demonstrate that the orientation of macromolecules and subsequent dynamic interactions at the biomolecule-nanoparticle (bio-nano) interfaces can be rationally controlled to engineer stimuli-responsive DNA nanomachines. The success of this design principle was demonstrated by engineering a series of antibody-responsive DNA walkers capable of moving persistently on a three-dimensional track made of DNA functionalized gold nanoparticles.

Investigating phosphorescence capability of halogen-substituted metal-free organic molecules: A theoretical study.

The radiative and non-radiative decay processes of five compounds are investigated through a comprehensive computational approach, for the aim of investigating the effect of different halogen substituents to the phosphorescent emission. Their optimal configurations at the ground (S) and lowest triplet excited (T) states are obtained and the calculated phosphorescent emission spectra are comparable with the experimental values. For 1,4-di(9H-carbazol-9-yl)benzene (PDCz), the electronic transition is between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), while for the four halides, the electronic transitions are attributed to several molecular orbitals.

A novel T-CN and seawater desalination.

A structurally stable stacked multilayer carbonitride is predicted with the aid of ab initio calculations. This carbonitride consists of C3N tetrahedra, and is similar to T-carbon and thus named T-C3N. Its 2-dimensional (2D) monolayer is also carefully investigated in this work.

Sensing mechanism of a fluorescent probe for thiophenols: Invalidity of excited-state intramolecular proton transfer mechanism.

Simple and effective detection of thiophenols has attracted great attention. A fluorescent probe 1 with high selectivity and sensitivity is designed and synthesized based on the excited-state intramolecular proton transfer (ESIPT) in experiment. However, we conclude that the ESIPT process fails to happen actually based on the calculation results.

Investigating detailed mechanism of hydrogen molecules adsorbing on single-wall carbon nanotubes using fitted force field parameters containing carbon-carbon interactions.

The nonbonded and bonded force field parameters for carbon atoms in single-wall carbon nanotubes (SWNT) are fitted by means of quantum chemistry calculations with considering the periodic boundary conditions. The nonbonded parameters between carbon atoms and hydrogen atoms are fitted as well. All the fitted parameters are verified by comparing to quantum chemistry results and by calculating Young's modulus.

Theoretical analysis of electrochromism under redox of bis(3-thienyl)/(2-thienyl)hexafluorocyclopentene: effects of charged and substituted systems.

Electrochromism with the ring-closing or ring-opening isomerization of substituted and unsubstituted bis(3-thienyl)/(2-thienyl)hexafluorocyclopentene is discussed using the DFT method. In the neutral ground state, bond making and breaking between two reactive C atoms on thienyls are thermodynamically forbidden. Under redox conditions, the gain or loss of electrons can have a significant effect on the frontier molecular orbital distribution of both open- and closed-ring isomers, particularly in reactive sites.

Repetitive exposure to low-dose X-irradiation attenuates testicular apoptosis in type 2 diabetic rats, likely via Akt-mediated Nrf2 activation.

To determine whether repetitive exposure to low-dose radiation (LDR) attenuates type 2 diabetes (T2DM)-induced testicular apoptotic cell death in a T2DM rat model, we examined the effects of LDR exposure on diabetic and age-matched control rats. We found that testicular apoptosis and oxidative stress levels were significantly higher in T2DM rats than in control rats. In addition, glucose metabolism-related Akt and GSK-3β function was downregulated and Akt negative regulators PTP1B and TRB3 were upregulated in the T2DM group.

Structural features and dynamic investigations of the membrane-bound cytochrome P450 17A1.

Cytochrome P450 (CYP) 17A1 is a dual-function monooxygenase with a critical role in the synthesis of many human steroid hormones. The enzyme is an important target for treatment of breast and prostate cancers that proliferate in response to estrogens and androgens. Despite the crystallographic structures available for CYP17A1, no membrane-bound structural features of this enzyme at atomic level are available.

Investigation of properties of Mg(n) clusters and their hydrogen storage mechanism: a study based on DFT and a global minimum optimization method.

The global minimum structures of Mgn clusters have been determined using the so-called "kick method". With the improved DFT method of B3PW91 functional and Grimme's dispersion correction, a series of the most stable structure of Mgn have been found and a novel Mg9 structure has been located. Subsequently, the chemisorption of hydrogen onto Mg clusters was systemically studied.

Heparin makes differences: a molecular dynamics simulation study on the human βII-tryptase monomer.

Human β-tryptase, an enzyme with trypsin-like activity in mast cells, is an important target for the treatment of inflammatory and allergy related diseases. Heparin has been inferred to play a vital role in the stabilization of the tryptase structure and the maintenance of its active form. Up to now, the structure-function relationship between heparin and the βII-tryptase monomer has not been studied with atomic resolution due to the lack of a complex structure of tryptase and heparin.

Mechanism of a pH-induced peptide inserting into a POPC bilayer: a molecular dynamic study.

Membrane insertion peptides have been developed in recent years and serve as cargos to deliver small molecules into cells. A class of membrane insertion peptides is the so called pH-induced peptides (pHLIPs), which are able to insert into membrane when the environment pH is acidic. Despite a number of experimental studies, the insertion process as well as the penetration mechanism is still worth study with computational methods.

The molecular configuration of a DOPA/ST monolayer at the air-water interface: a molecular dynamics study.

In this study, surface pressure-area isotherms for N-stearoyldopamine (DOPA) and 4-stearylcatechol (ST) monolayers are obtained by means of molecular dynamics simulations and compared to experimental isotherms. The difference between DOPA and ST is an amide group, which is present in the alkyl tails of DOPA molecules. We find a large difference between the isotherms for DOPA and ST monolayers.

Molecular dynamics simulation of a DOPA/ST monolayer on the Au(111) surface.

In order to study the influence of molecular structure on the formation of a monolayer, two molecules have been considered, namely N-stearoyldopamine (DOPA) and 4-stearyl-catechol (ST). The difference between these two molecules is the amide group in DOPA. By investigating these monolayers at different surface areas per molecule, the molecular configurations of a DOPA/ST monolayer on the Au(111) surface were obtained.

Enhanced fluoride adsorption using Al (III) modified calcium hydroxyapatite.

Aluminum-modified hydroxyapatite (Al-HAP) was prepared and characterized using XRD and BET analyses. Al-HAP possessed higher defluoridation capacity (DC) of 32.57 mgF(-)/g than unmodified hydroxyapatite (HAP) which showed a DC of 16.