Preparation and Properties of Polyethylene Terephthalate (PET)/Near Infrared Reflective Pigment (NIR) Composites

A near infrared reflective (NIR, nickel antimony titanium yellow rutile) pigment filler was incorporated into a polyethylene terephthalate (PET) matrix via a melt blending approach to increase the infrared reflection of PET and limit the thermal heat accumulation in light of environmental and energy conservation concerns. Two different types of surface modifiers, polyethylene glycol (PEG) and cetyltrimethylammonium bromide (CTAB), were used to modify the NIR surface, as NIR–PEG and NIR–CTAB fillers, to investigate the surface modification effect. Fourier transform infrared spectroscopy (FTIR), a Zetasizer, and electron spectroscopy for chemical analysis (ESCA) results suggested a successful adsorption of the organic modifiers onto the NIR surface. Thermogravimetric analysis indicated a higher adsorption degree for the CTAB modifier than the PEG modifier due to the electronic interaction between CTAB and NIR. The thermal crystallization temperature (T_c) for neat NIR-filled samples decreased with increasing NIR content within the PET matrix at first, up to 9°C, but then tended to increase again up to a measurable difference of 6°C with respect to pure PEG, indicating the promotion of the crystallization kinetics of the neat NIR within the PET matrix. On the other hand, a decrease in T_c for all NIR-CTAB or NIR-PEG loadings was found, with the depression close to 10°C for all NIR-CTAB samples regardless of the loading. CTAB modified NIR gave the highest improvement in tensile strength and strain at break in comparison with NIR and NIR-PEG filled samples. The near infrared reflection values of modified PET were higher than those of neat PET. The reflection values appeared to be the highest for some concentrations of the NIR-CTAB filled samples, but were of similar orders of magnitude with those for NIR or NIR-PEG filled samples.     

Preparation and Flammability of a Flame-Retardant Poly(Butyl Acrylate-Vinyl Acetate) System Based on Gemin-Surfactant Modified Montmorillonite and Ammonium Polyphosphate

Gemin-surfactant modified montmorillonite (G-MMT) was successfully prepared by an ion exchange reaction and characterized via Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The P(BA-VAc)/G-MMT emulsion was prepared via an in-situ polymerization method using potassium persulfate (K₂S₂O₈, KPS) as an initiator. Ammonium polyphosphate (APP) was introduced for obtaining P(BA-VAc)/APP/G-MMT flame-retardant latex with a constant total content of 15 wt% of APP and G-MMT in P(BA-VAc). The flame retardancy and thermal behavior of the latex films were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and thermal gravimetric analysis (TG/DTA). Compared with the P(BA-VAc)/APP composite, the LOI value of P(BA-VAc)/APP/G-MMT containing 0.5 wt% G-MMT at the same total additive loading increased to 29.1 from 20.0 and its UL-94 increased from no rating to V-0. Thermal gravimetric (TG) data showed that the amount of residues increased significantly with the loading of G-MMT. In addition, the LOI values increased with the increase in char residues. The morphology and microstructure of the residues generated during LOI testing were investigated by scanning electron microscopy (SEM). The outer surfaces of P(BA-VAc)/APP/G-MMT charred layers were more continuous and compact than those of P(BA-VAc)/APP.     

Interaction of Moxifloxacin with Bovine Hemoglobin and Effect of the Coexistent Drugs on the Reaction

The interaction between moxifloxacin (MXFX) and Bovine Hemoglobin (BHb) was investigated at different temperatures by fluorescence spectroscopy. Results showed that the quenching mechanism of MXFX on BHb was a static quenching process with Förester spectroscopy energy transfer. The primary binding for MXFX was located at β-37 Tryptophan residue in hydrophobic cavity of BHb. Besides, weak negative cooperativity was found in drug's binding with BHb. Synchronous spectra revealed that the microenvironment and the conformation of serum albumin were changed during the reaction. Most antibiotics had no effect on the system of BHb-MXFX, except quinolone antibiotics. The system had good stability.     

Binding Study of Phenformin with Bovine Serum Album Using a Combined Technique of Equilibrium Dialysis with Flow-Injection Chemiluminescence Detection

ABSTRACT

The interaction between phenformin hydrochloride and bovine serum albumin (BSA) was investigated by the methods of chemiluminescence combined with equilibrium dialysis technique. A novel N-bromosuccinimide (NBS)–eosin Y (EY) chemiluminescence (CL) method was established for the determination of phenformin. The mechanism of this chemiluminescence system was proposed. Optimization studies were performed to determine the phenformin. Under the optimal conditions, the CL intensity was linear for a phenformin concentration over the range of 4.6 × 10^?8 to 5.0 × 10^?5 g/mL. The detection limit was 1.5 × 10^?8 g/mL. The data obtained by the present equilibrium dialysis–CL system were analyzed using the Klotz plot and the Scatchard analysis. The results showed that the Klotz plot and the Scatchard plot are linear with good correlation coefficient, indicating that the phenformin has only one type of binding site on BSA. The binding parameters were the number of the binding sites n (1.02) and the estimated association constant K (2.66 × 10⁴ L/mol). The chemiluminescence system combined with equilibrium dialysis developed in this work demonstrated its use for determination of interaction between drug and protein by using relatively simple instrument.     

A Novel Pyrene Fluorescent Sensor Based on the π–π Interaction Between Pyrene and Graphene of Graphene–Cadmium Telluride Quantum Dot Nanocomposites

In this article, water-soluble graphene–cadmium telluride quantum dot nanocomposites were fabricated through the synthesis of cadmium telluride quantum dots in the presence of graphene aqueous dispersion. It was found that pyrene could remarkably quench fluorescence of graphene–cadmium telluride quantum dot nanocomposites. On this basis, a novel method for the determination of pyrene was developed. Factors affecting the pyrene detection were investigated, and the optimum conditions were determined. Under the optimum conditions, a linear relationship could be established between the quenching of fluorescence intensity of graphene–cadmium telluride quantum dot nanocomposites and the pyrene concentration in the range of 6.00 × 10^?8–2.00 × 10^?6 mol L^?1 with a correlation coefficient of 0.9959. The detection limit was 4.02 × 10^?8 mol L^?1. Furthermore, the nanocomposites were applied to practical determination of pyrene in different water samples with satisfactory results.     

Modified Spectral Neugebauer Model for Printer Characterization

Spectral Neugebauer model is widely used for spectral reflectance prediction during printer characterization. However, several factors reduce the predication precision. Thus, an improved cellular Yule-Nielson spectral Neugebauer (CYNSN) model is proposed, which modifies the traditional spectral Neugebauer model in three main aspects: (1) First, in order to adjust the nonlinearities between the predicated and measured spectral reflectance, an iteratively calculated Yule-Nielson exponent is added to the reflectance values within the Neugebauer equations. (2) Second, the quantity of Neugebauer primaries is increased by dividing the CMY colorant space into 4³ uniform cellular subdomains. (3) Third, the mapping functions are developed to map the area coverages' theoretical values to their effective values within the subdomains, and the mapped values highly improve the matching degree of the predicated and measured reflectance values. In the experiment, four related spectral Neugebauer models are employed during printer characterization, which are the traditional spectral Neugebauer model, Yule-Nielson spectral Neugebauer (YNSN) model, traditional CYNSN model, and the modified CYNSN model, respectively. And the experimental results show the modified CYNSN model yields a significant improvement over the other spectral Neugebauer models, by comparing the characterization errors in the form of colorimetry and spectroscopy.     

Effect of deposition power and pressure on rate deposition and resistivity of titanium thin films grown by DC magnetron sputtering

ABSTRACT

Based on magnetron sputtering deposition technology, titanium (Ti) thin films are deposited on silicon (Si) substrate using different preparation conditions such as sputtering power and pressure. The influence of altering these conditions on deposition rate and microstructure is studied. The results show that sputtering power significantly affects the rate of deposition and the resistivity. The deposition rate of the Ti thin film increases when the resistivity decreases under sputtering powers of 150–225?W with a pressure of 0.8?Pa and Argon (Ar) flux of 80 sccm. As sputtering power was increased further (from 225 to 250?W), the deposition rate reduced and the resistivity augmented. Pressure also has influence on the deposition rate and resistivity – when pressure increases from 0.6 to 0.8?Pa, the deposition rate escalates while the resistivity reduces; when the pressure is raised from 0.8 to 1.0?Pa with Ar flux of 100 sccm, the deposition rate decreases and resistivity increases. The surface chemical compositions and the structures of the Ti film were studied by using X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer (XRD). Observing the cross-section of the thin-film samples produced by scanning electron microscope (SEM) reveals the influence of the preparation conditions used on the microstructure and confirms the influence of sputtering power and pressure on the resistivity.     

Selection of optimal combinations of inputs in a partial least squares model for prediction of soil organic matter

Abstract

Partial least squares model is widely used in estimation of soil physical and chemical parameters such as soil organic matter and moisture content, due to its advantages in dealing with collinearity of variables like hyperspectral reflectance. However, it is hard to determine optimal combination of partial least squares model input for soil organic matter prediction since there are lots of possibilities such as, different mathematical transformation of spectral reflectance, wavelength ranges, and spectral resolution. Laboratory hyperspectral reflectance of soils in Songnen plain were analyzed in this study, and the orthogonal experimental design method for deriving optimal combination of input variables for soil organic matter prediction models was introduced. For intercalating orthogonal experimental design table, five different levels which commonly used by researchers were assigned to factors. Results show that the optimal combination input for single black soil is using the derivative logarithmic reciprocal reflectance in the wavelength range selected by multiple stepwise regression at a spectral resolution of 5?nm (R²=?0.95, RMSE?=?0.21, and RPD?=?4.49), and different soils is using continuum removed in the wavelength range selected by MSR at a spectral resolution of 5?nm (R²?=?0.77, RMSE?=?0.74, and RPD?=?2.08). With optimal combination input, the partial least squares model prediction ability was evaluated as excellent for single black soil, possible for different soils. This study illustrates the orthogonal experimental design method can be an effective way to identify the optimal input variables of a partial least squares model for soil organic matter prediction, and multiple stepwise regression can be a preprocessing step to reduce hyperspectral data redundancy before using partial least squares to predict soil organic matter. Overall, this study provides a new approach for determining optimal input of partial least squares predicting model.     

Influence on drug efficacy of the binding behavior of pioglitazone hydrochloride with tryptophan residues,and tyrosine residues in bovine transferrin

Abstract

The interaction of pioglitazone hydrochloride bound to tryptophan residues and tyrosine residues in bovine transferrin was investigated using synchronous fluorescence spectroscopy at various temperatures (298, 310, and 318?K). From binding constants and thermodynamic parameters, it was shown that 1:1 stable compound was formed by the electrostatic force interaction of pioglitazone hydrochloride bound to tryptophan residues and tyrosine residues in bovine transferrin. The extent of binding between pioglitazone hydrochloride and tryptophan residues in bovine transferrin was more than that between pioglitazone hydrochloride and tyrosine residues in bovine transferrin. At 310?K, the fluorescence quenching ratio number of tyrosine residues and tryptophan residues in bovine transferrin were 47.52% and 54.19%, respectively, which indicated that the fluorescence contribution of tryptophan residues was greater. At 310?K, pioglitazone hydrochloride-tyrosine residues(in bovine transferrin) binding rate were 55.60–73.82%, and the combined model was W?=??0.0315R²???0.1520R?+?0.7385. The value of Hill’s coefficients was greater than 1, which suggested that there was a positive cooperativity between pioglitazone hydrochloride and subsequent ligands. The results of molecular docking were consistent with that of experimental calculation.     

The Mineral Content of Rhizona cyperi after Microwave-Assisted Digestion and Determination by AAS

ABSTRACT

Rhizoma cyperi (tuberal part of Cyperus rotundus Linn) obtained from 15 different zones of China was studied to determine the contents of 16 trace elements such as 4 minor (Ca, K, Mg, and Na), 9 trace (Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn), and 3 toxic (Ag, Cd, and Pb) elements. The concentration determination of 16 elements was performed by atomic absorption spectrophotometry (AAS) after microwave-assisted digestion. A microwave-assisted digestion procedure based on the mixture nitric acid–hydrogen peroxide was evaluated. The method was successfully validated with the good recoveries (97–105%) against CRM GBW07603 (bush twigs and leaves). The calibration curve furnished good linear correlation coefficients (r = 0.9956–0.9999), excellent recoveries (99.35–103.7%), and limits of detection (LOD = 1–50 ng·mL^?1) suitable to determine in Rhizoma cyperi. The results showed that K, Ca, Mg, and Na were the most abundant of the major elements in Rhizoma cyperi with average concentrations of K, 26,221 µg·g^?1; Ca, 1097 µg·g^?1; Mg, 714 µg·g^?1, and Na, 293 µg·g^?1, respectively. K element was determined for the first time in this plant.