A first-principles molecular dynamics approach for predicting optical phonon lifetimes and far-infrared reflectance of polar materials

The Lorentz oscillator model is well-known for its effectiveness to describe the far-infrared optical properties of polar materials. The oscillator strength and damping factor in this model are usually obtained by fitting to experimental data. In this work, a method based on first-principles simulations is developed to parameterize the Lorentz oscillator model without any fitting parameters. The high frequency dielectric constant is obtained from density functional perturbation theory, while the optical phonon frequencies and damping factors are calculated using an analysis of ab initio molecular dynamics trajectories. This method is then used to predict the far-infrared properties of GaAs, and the results are in good agreement with experimental data.     

Regularity of Global Attractor for Atmospheric Circulation Equations with Humidity Effect

Acta Mathematicae Applicatae Sinica, English Series - In this article, regularity of the global attractor for atmospheric circulation equations with humidity effect is considered. It is proved that...     

A facile method for preparation of green and antibacterial hydrogel based on chitosan and water-soluble 2,3-dialdehyde cellulose

Cellulose - Chitosan (CS) has been widely used to prepare natural hydrogel duo to its characteristics. However, most of the methods of preparing CS-based hydrogel are complicated and not green,...     

Hypergrafted nano-silica modified polymer gel electrolyte for high-performance solid-state supercapacitor

In the developing of wearable electronics and smart textiles, thin, lightweight, and flexible energy storage supercapacitor with high energy density has attracted the attention of many researchers in recent years. In this work, we prepared gel nano-composite electrolyte with the hypergrafted poly (amine-ester) nano-silica (HBPAE-SiO₂) as inclusion. The electrochemical properties of the supercapacitor with the alkaline polymer electrolyte were evaluated by cyclic voltammetry, galvanostatic charge–discharge behavior, and electrochemical impedance spectroscopy. It was found that the incorporated HBPAE-SiO₂ can greatly increase the specific capacitance of the supercapacitor, which was due to the enhanced ionic conductivity of gel electrolyte as well as good electrode–electrolyte contact. It is pointed out that the electroactivity of the inclusion may be also one reason. The best specific capacitance with 30 wt% HBPAE-SiO₂ reached 160 F g^?1, which was increased by 36.5 % compared with that of polyvinyl alcohol (PVA)-KOH system. Moreover, the capacity retention of solid-state supercapacitor can be 88 % after 10,000 cycles. The hypergrafted nano-silica modified polymer gel electrolyte is promising for the application of solid-state supercapacitor.     

Molecular Logic Gates and Switches Based on 1,3,4‐Oxadiazoles Triggered by Metal Ions

Organic molecular devices for information processing applications are highly useful building blocks for constructing molecular‐level machines. The development of “intelligent” molecules capable of performing logic operations would enable molecular‐level devices and machines to be created. We designed a series of 2,5‐diaryl‐1,3,4‐oxadiazoles bearing a 2‐(para‐substituted)phenyl and a 5‐(o‐pyridyl) group (substituent X=NMe₂, OEt, Me, H, and Cl; 1 a – e ) that form a bidentate chelating environment for metal ions. These compounds showed fluorescence response profiles varying in both emission intensity and wavelength toward the tested metal ions Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺ and the responses were dependent on the substituent X, with those of 1 d being the most substantial. The 1,3,4‐oxadiazole O or N atom and pyridine N atom were identified as metal‐chelating sites. The fluorescence responses of 1 d upon metal chelation were employed for developing truth tables for OR, NOR, INHIBIT, and EnNOR logic gates as well as “ON‐OFF‐ON” and “OFF‐ON‐OFF” fluorescent switches in a single 1,3,4‐oxadiazole molecular system.     

Sensitive and simple detection of Escherichia coli strain based on time-resolved fluorescence DNA hybridization assay

A two-probe tandem DNA hybridization assay based on time-resolved fluorescence was employed to detect Escherichia coli strain. The amino modified capture probe was covalently immobilized on the common glass slide surface. The Eu(TTA)₃(5-NH₂-phen) with the characteristics of long lifetime and intense luminescence was labeled with reporter probe. The original extracted DNA samples without the purification and amplification process were directly used in the hybridization assay. The concentration of capture probe, hybridization temperature, hybridization and washing time were optimized. The detection limit is about 1.49 × 10³ CFU mL⁻¹E. coli cells, which is comparable to the value of most microbiology methods. The proposed method has the advantages of easy operation, satisfactory sensitivity and specificity, which can provide a promising technique for monitoring the microorganisms.     

Structural elucidation of in vivo metabolites of phencynonate and its analogue thiencynonate in rats by HPLC-ESI-MS

The structural elucidation of the metabolites of phencynonate and its analogue thiencynonate in rats was performed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MSⁿ) in positive ion mode, by comparing their changes in molecular masses (ΔM), retention times and spectral patterns with those of the parent drug. Phencynonate and thiencynonate were easily biotransformed in vivo by the pathways of N-demethylated, oxidative, hydroxylated and methoxylated to form seventeen metabolites that retained the some features of the two parent molecules. These metabolites included ten phencynonate metabolites (N-demethyphencynonate monoxide, N-demethyhydroxy phencynonate, phencynonate monoxide, hydroxyphencynonate, phencynonate dioxide, methoxyphencynonate, dihydroxyphencynonate, dihydroxyphencynonate, hydroxymethoxy phencynonate, trihydroxyphencynonate) and seven thiencynonate metabolites (N-demethy thiencynonate, N-demethythiencynonate monoxide, N-demethyhydroxythiencynonate, thiencynonate monoxide, hydroxythiencynonate, hydroxythiencynonate monoxide, dihydroxy thiencynonate). The described method has wide applicability to rapidly screen and provide structural information of these metabolites. The identifications of precise structures of these metabolites need to be confirmed by other techniques such as the ¹H and ¹³C NMR.     

Time-resolved fluorescence aptamer-based sandwich assay for thrombin detection

In the present study, the authors report a novel sensitive method for the detection of thrombin using time-resolved fluorescence sensing platform based on two different thrombin aptamers. The thrombin 15-mer aptamer as a capture probe was covalently attached to the surface of glass slide, and the thrombin 29-mer aptamer was fluorescently labeled as a detection probe. A bifunctional europium complex was used as the fluorescent label. The introduction of thrombin triggers the two different thrombin aptamers and thrombin to form a sandwich structure. The fluorescence intensity is proportional to the thrombin concentration. The present sensing system could provide both a wide linear dynamic range and a low detection limit. The proposed sensing system also presented satisfactory specificity and selectivity. Results showed that thrombin was retained at the aptamer-modified glass surface while nonspecific proteins were removed by rinsing with buffer solution. This approach successfully showed the suitability of aptamers as low molecular weight receptors on glass slides for sensitive and specific protein detection.     

非对称方势阱中的激子及其与声子的相互作用

采用类LLP(Lee-Low-Pines)变换和分数维变分法,在讨论有限深非对称方势阱Ga_1－xAl_xAs/ GaAs/Ga_0.7Al_0.3As的分数维基础上,计算了其中激子的基态能量以及声子对其影响,随着势阱宽度增加,激子能量先减小后增大,出现一个最小值.讨论了一侧势垒高度变化对分数维、激子基态能量的影响,并发现声子作用使得激子能量明显增大.另外,非对称方势阱中的激子结合能随阱宽的减小而增     

An experimental investigation on two-dimensional shape-based diffuse optical tomography

A two-dimensional （2D） shape-based approach of image reconstruction using a boundary element method is developed for diffuse optical tomography （DOT）. The experimental validation uses a four-channel time- correlated single photon counting （TCSPC） system for detection and an intensity data-type for image reconstruction. The optical and geometric parameters are simultaneously recovered using a difference imaging scheme. Results demonstrate that the proposed DOT modality is a promising methodology of in vivo reconstruction of the optical structures of tissues.