Secondary channel estimation in spatial active noise control systems using a single moving higher order microphone.

Spatial active noise control (ANC) systems focus on minimizing unwanted acoustic noise over continuous spatial regions by generating anti-noise fields with secondary loudspeakers. Conventionally, error microphones are necessary inside the region to measure the channels from the secondary loudspeakers to the error microphones and record the residual sound field during the noise control. These error microphones highly limit the implementation of spatial ANC systems because of their impractical geometry and obstruction to the users from accessing the region. Recent advances, such as virtual sensing, focus on ANC with microphones placed away from the region. While these techniques relax the usage of error microphones during the noise control, an error microphone array remains necessary during the secondary channel estimation. In this paper, we propose a method to estimate secondary channels without using an error microphone array. Instead, a moving higher order microphone is applied to obtain the secondary channels from the secondary loudspeakers to the region of interest, which includes all desired error microphone locations. By simulation, we show that the proposed method is robust against various measuring errors introduced by the movement of the microphone and is suitable for the secondary channel estimation in spatial ANC systems.

RuO2/rGO heterostructures as mimic peroxidases for colorimetric detection of glucose.

The successful synthesis of ruthenium oxide/reduced graphene oxide (RuO2/rGO) heterostructures by one-pot hydrothermal method using graphene oxides and RuCl3 as precursors is reported. The heterostructures had high peroxidase-like (POD-like) activities, which catalyzes the oxidation of classical peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to create a blue colored reaction product. The catalytic activity was significantly enhanced by the synergistic effect between RuO2 nanoparticles and rGO. RuO2/rGO had a low Km of 0.068 mM and a high vmax of 1.228 × 10-7 M·s-1 towards TMB in the TMB-H2O2 catalytic oxidation system. In addition, the POD-like activity originating from the electron transfer mechanism was confirmed by cytochrome C (Cyt C) oxidation experiment. A colorimetric method based on RuO2/rGO heterostructures was developed with good sensitivity and selectivity for glucose detection with a limit of detection of 3.34 µM and a linear range of 0-1500 µM. The RuO2/rGO heterostructures have potential applications in the biomedical areas, such as biosensor and diagnostics.

The Effects of Sodium Propionate Supplementation in the Diet with High Soybean Meal on Growth Performance, Intestinal Health, and Immune Resistance to Bacterial Infection in Turbot (Scophthalmus maximus L.).

Short-chain fatty acids (SCFAs) are the products of the microbial fermentation of dietary fiber in the intestine. Acetate, propionate, and butyrate are the most abundant SCFA metabolites and play an important role in maintaining host health. This study was aimed at investigating the effects of sodium propionate (NaP) supplementation in the diet with a high proportion of soybean meal (SBM) on the growth, inflammatory status, and anti-infectious ability in juvenile turbot. Four experimental diets were designed: (1) fish meal- (FM-) based diet (control group), (2) SBM protein replacing 45% FM protein in the diet (high SBM group), (3) 0.5% NaP supplementation in the high SBM diet (high SBM+0.5% NaP group), and (4) 1.0% NaP supplementation in the high SBM diet (high SBM+1.0% NaP group). The results confirmed that the fish fed the high SBM diet for 8 weeks showed the decreased growth performance, the typical enteritis symptoms, and the increased mortality responding to Edwardsiella tarda (E. tarda) infection. However, 0.5% NaP supplementation in the high SBM diet promoted the growth performance of turbot and restored the activities of digestive enzymes in the intestine. Moreover, dietary NaP ameliorated the intestinal morphology, enhanced the expression of intestinal tight junction proteins, improved the antioxidant capacity, and suppressed the inflammatory status in turbot. Finally, the expression of antibacterial components and the resistance to bacterial infection were increased in NaP-fed turbot, especially in high SBM+1.0% NaP group. In conclusion, the supplementation of NaP in high SBM diet promotes the growth and health in turbot and provides a theoretical basis for the development of NaP as a functional additive in fish feed.

Recent Progress of Nanozymes in the Detection of Pathogenic Microorganisms.

Infectious diseases are among the world's principal health problems. It is crucial to develop rapid, accurate and cost-effective methods for the detection of pathogenic microorganisms. Recently, considerable progress has been achieved in the field of inorganic enzyme mimics (nanozymes). Compared with natural enzymes, nanozymes have higher stability and lower cost. More interestingly, their properties can be designed for various demands. Herein, we introduce the latest research progress on the detection of pathogenic microorganisms by using various nanozymes. We also discuss the current challenges of nanozymes in biosensing and provide some strategies to overcome these barriers.

Colorimetric determination of ascorbic acid using a polyallylamine-stabilized IrO2/graphene oxide nanozyme as a peroxidase mimic.

The authors describe a peroxidase-mimicking nanozyme composed of IrO2 and graphene oxide (GO). It was synthesized from monodisperse IrO2 nanoparticles with an average diameter of 1.7 ± 0.3 nm that were prepared by pulsed laser ablation in ethanol. The nanoparticles were then placed on polyallylamine-modified GO nanosheets through electrostatic interaction. The peroxidase-like activity of the resulting nanocomposites was evaluated by catalytic oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of H2O2. Kinetic results demonstrated that the catalytic behavior of the nanocomposites follows Michaelis-Menten kinetics. Experiments performed with terephthalic acid and cytochrome C confirmed that the peroxidase-like activity originated from the electron transfer mechanism rather than from generation of hydroxy radicals. The peroxidase-like activity is inhibited in the presence of ascorbic acid (AA). Based on this property, a colorimetric assay was developed for the determination of AA by exploiting the peroxidase-like activity of IrO2/GO nanocomposites. The linear relationship between absorbance at 652 nm and the concentration of AA was acquired. The limit of detection for AA is 324 nM. Further applications of the method for AA detection in real samples were also successfully demonstrated. Graphical abstractSchematic of the preparation of polyallylamine (PAH)-stabilized IrO2/GO nanocomposites and the colorimetric detection of AA based on the peroxidase-like activity of IrO2/GO nanocomposites.

Using the UPLC-ESI-Q-TOF-MSE method and intestinal bacteria for metabolite identification in the nonpolysaccharide fraction from Bletilla striata.

Bletilla striata (Thunb.) Reichb. f. (Orchidaceae), also known as Bai-ji, is a traditional Chinese herb that is widely used in Asia to treat hematemesis, hemoptysis, traumatic bleeding and other similar disorders. Most studies have focused on the pharmacological activities of polysaccharide extracts from B. striata. Our previous studies found that the nonpolysaccharide fraction from B. striata extract also has a hemostatic effect; however, the active constituents responsible for this pharmacological action are unclear. Thus, the metabolic profiles of the nonpolysaccharide fraction were investigated in Sprague-Dawley rats and intestinal bacteria models using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Mass data were acquired by the MSE method. Eight components including five prototypes and three metabolites were identified in rat biofluids after oral administration of the nonpolysaccharide fraction. The parent compounds underwent various metabolic processes, including hydrolysis, deglucosylation, glycosylation and sulfate conjugation. The results not only reveal the possible metabolic pathway, but also indicate the potential pharmacological components. Further mechanistic studies using nonpolysaccharide compounds of the B. striata extract are required to obtain potential candidate compounds.

HfO2/porous anodic alumina composite films for multifunctional data storage media materials under electric field control.

New materials for achieving direct electric field control of ferromagnetism and resistance behavior are highly desirable in the development of multifunctional data storage devices. In this paper, HfO2 nanoporous films have been fabricated on porous anodic alumina (PAA) substrates by DC-reactive magnetron sputtering. Electrically induced resistive switching (RS) and modulated room temperature ferromagnetism are simultaneously found in a Ag/HfO2/PAA/Al (Ag/HP/Al) heterostructure. The switching mechanism between low resistance state and high resistance state is generally attributed to the formation/rupture of conductive filaments which may consist of oxygen vacancies. The combination of the electric field control of magnetization change and RS makes HP films possible for the multifunctional data storage media materials.

A UPLC-MS/MS Method for Simultaneous Determination of Free and Total Forms of a Phenolic Acid and Two Flavonoids in Rat Plasma and Its Application to Comparative Pharmacokinetic Studies of Polygonum capitatum Extract in Rats.

The principal active constituents of Polygonum capitatum are phenolic acids and flavonoids, such as gallic acid, quercitrin, and quercetin. The aim of this study was to develop and validate a method to determine the three constituents and the corresponding conjugated metabolites of Polygonum capitatum in vivo and to conduct pharmacokinetic studies on the herb, a well-known Miao medicinal plant in China. Gallic acid, quercitrin, and quercetin were analysed by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Protein precipitation in plasma samples was performed using methanol. For the determination of total forms of analytes, an additional process of hydrolysis was conducted using ß-glucuronidase and sulphatase. The analytes were separated on a BEH C18 column (50 mm × 2.1 mm; i.d., 1.7 µm) and quantified by multiple reaction monitoring (MRM) mode. The linear regression showed high linearity over a 729-fold dynamic range for the three analytes. The relative standard deviations of intra- and inter-day measurements were less than 9.5%, and the method was accurate to within -11.1% to 12.5%. The extraction recoveries for gallic acid, quercitrin, and quercetin were 94.3%-98.8%, 88.9%-98.8%, and 95.7%-98.5%, respectively. All samples were stable under short- and long-term storage conditions. The validated method was successfully applied to a comparative pharmacokinetic study of gallic acid, quercitrin, and quercetin in their free and total forms in rat plasma. The study revealed significantly higher exposure of the constituents in total forms for gallic acid and quercetin, while quercitrin was detected mainly in its corresponding free form in vivo. The established method was rapid and sensitive for the simultaneous quantification of free and total forms of multiple constituents of Polygonum capitatum extract in plasma.

[Analysis of metabolites of quercitrin in rat intestinal flora by using UPLC-ESI-Q-TOF-MS/MS].

To investigate the metabolism of quercitrin in rat intestinal flora and possible biological pathways, laying the foundation for the metabolic mechanism of traditional Chinese medicine glycosides ingredients. UPLC-Q-TOF-MS/MS method was established to detect the quercitrin and its metabolites with 0.1% formic acid solution(A)-0.1% formic acid acetonitrile(B) as the mobile phase for gradient elution at a flow rate of 0.3 mL•min⁻¹. Electrospray negative ion mode was applied to analyze the metabolites of quercitrin in rat intestinal flora. Metabolite ToolsTM, mass defect filter(MDF) and other technologies were used to screen, analyze the metabolites and infer the chemical formula of the metabolites. The results showed that quercitrin would have degalactoside, deoxygenation and acetylation reactions, and the aglycone quercetin resulted from degalactoside would have further reactions such as hydroxylation, deoxygenation, reduction, and ring opening to achieve deoxygenation metabolite kaempferol, C2-C3 double bonds hydrogenation and reduction product taxifolin, and degalactoside product quercetin. The research results showed that quercitrin can be metabolized by rat intestinal flora, which could increase their hydrophobicity and chemical diversity.

Synthesis of ultrathin TiO2/Ti films with tunable structural color.

A series of ultrathin TiO2/Ti films with iridescent structural colors were fabricated on high-purity titanium sheets via a one-step anodization procedure. Tunable color in the films can be obtained by adjusting the anodization time and can be adjusted across the entire visible range. It was found that all the films displayed highly saturated colors. Trichromatic coordinates of color x, y were delineated, and the color was identified by positioning the x and y values in the Commission International de I'Eclairage chromaticity diagram. Theoretical and experimental results of the changes in the structural color according to the principle of complementary colors are consistent with the experimental results. The TiO2/Ti films may have potential in color displays, decoration, and anticounterfeiting technology.