Catalytic kinetic spectrophotometric determination of trace copper with copper(II)- p-acetylchlorophosphonazo-hydrogen peroxide system

Copper(II) catalyzes the oxidation of p-acetylchlorophosphonazo(CPApA) by hydrogen peroxide in 0.10 M phosphoric acid. A novel catalytic kinetic-spectrophotometric method is proposed for the determination of copper based on this principle. Copper(II) can be determined spectrophotometrically by measuring the decrease in the absorbance of CPApA at the wavelength of 554 nm using the fixed-time method. The optimum reaction conditions are as follows: H3PO4 (1.00 M) 1.0 mL, CPApA (2.19 × 10-4 M) 1.5 mL, H2O2(4.30 × 10-2 M) 1.2 mL, reaction temperature 100 oC and reaction time 13 min. The linear range for the determination of copper(II) is 0.020-0.30 μg/mL. The limit of detection is 10.94 ng/mL. The method was satisfactorily used to determine copper in tomato and cucumber samples. The relative standard deviation of thirteen replicate determinations was 1.20-1.34% and the recovery of the method was 99.5-103.9%

Kinetic spectrophotometric determination of iron based on catalytic oxidation of p-acetylarsenazo

A novel catalytic kinetic spectrophotometric method for the determination of iron is developed based on the catalytic effect of Fe(III) on the oxidation reaction of p-acetylarsenazo(ASApA) by potassium periodate. Maximum absorbance of the Fe(III)-ASApA-KIO4 system in 8.0 × 10-3 M sulfuric acid occurs at the wavelength of 540 nm. The change in absorbance (DA) is linearly related with the concentration of iron(III) in the range of 0.10-4.0 ng/mL and fitted the equation: DA = 4.91 × 10-2 C (C: ng/mL) + 0.017, with a regression coefficient of 0.9966 at the wavelength. The detection limit of the method is 0.031 ng/mL. The relative standard deviation of the method was from 1.34% to 1.78% for 11 replicate determinations. The standard addition recovery of the method ranged from 95.71% to 103.3%. The method was used to determine iron in the black gingili paste, oat slice, sleeve-fish silk food samples. The determined results were in agreement with those byatomic absorption spectrometry

Valley-dependent Brewster angles and Goos-Hanchen effect in strained graphene

We demonstrate theoretically how local strains in graphene can be tailored to generate a valley polarized current. By suitable engineering of local strain profiles, we find that electrons in opposite valleys (K or K') show different Brewster-like angles and Goos-H\"anchen shifts, exhibiting a close analogy with light propagating behavior. In a strain-induced waveguide, electrons in K and K' valleys have different group velocities, which can be used to construct a valley filter in graphene without the need for any external fields.Comment: 5 pages, 4 figure

Investigation of the Viscoelastic Effect on Optical- Fiber Sensing and Its Solution for 3D-Printed Sensor Packages

Viscoelasticity is an effect seen in a wide range of materials and it affects the reliability of static measurements made using Fiber Bragg Grating-based sensors, because either the target structure, the adhesive used, or the fiber itself could be viscoelastic. The effect of viscoelasticity on FBG-based sensing has been comprehensively researched through theoretical analysis and simulation using a finite-element approach and a further data processing method to reconstruct the graphical data has been developed. An integrated sensor package comprising of an FBG-based sensor in a polymer host and manufactured by using three-dimensional printing was investigated and examined through tensile testing to validate the approach. The application of the 3D-printed FBG-based sensor package, coupled to the data process method has been explored to monitor the height of a railway pantograph, a critical measurement requirement to monitor elongation, employing a method that can be used in the presence of electromagnetic interference. The results show that the effect of viscoelasticity can be effectively eliminated, and the graphical system response allows results that are sufficiently precise for field use to be generated

Spin current diode based on an electron waveguide with spin-orbit interaction

We propose a spin current diode which can work even in a small applied bias condition (the linear-response regime). The prototypal device consists of a hornlike electron waveguide with Rashba spin-orbit interaction, which is connected to two leads with different widths. It is demonstrated that when electrons are incident from the narrow lead, the generated spin conductance fluctuates around a constant value in a wide range of incident energy. When the transport direction is reversed, the spin conductance is suppressed strongly. Such a remarkable difference arises from spin-flipped transitions caused by the spin-orbit interaction.Comment: 3 pages, 2 figure

Anti-ISI Demodulation Scheme and Its Experiment-based Evaluation for Diffusion-based Molecular Communication

In diffusion-based molecular communication (MC), the most common modulation technique is based on the concentration of information molecules. However, the random delay of molecules due to the channel with memory causes severe inter-symbol interference (ISI) among consecutive signals. In this paper, we propose a detection technique for demodulating signals, the increase detection algorithm (IDA), to improve the reliability of concentration-encoded diffusion-based molecular communication. The proposed IDA detects an increase (i.e., a relative concentration value) in molecule concentration to extract the information instead of detecting an absolute concentration value. To validate the availability of IDA, we establish a real physical tabletop testbed. And we evaluate the proposed demodulation technique using bit error rate (BER) and demonstrate by the tabletop molecular communication platform that the proposed IDA successfully minimizes and even isolates ISI so that a lower BER is achieved than the common demodulation technique

The effect of comorbid attention-deficit/hyperactivity disorder symptoms on face memory in children with autism spectrum disorder: Insights from transdiagnostic profiles

Face memory impairments are common but heterogeneous in autism spectrum disorder (ASD), which may be influenced by co-occurrence with attention-deficit/hyperactivity disorder (ADHD). Here, we aimed to investigate the phenotype change of face memory in children with ASD comorbid ADHD symptoms, and discuss the potential role of executive function (EF). Ninety-eight children were analyzed in the present study, including ASD- (ASD-only, n = 24), ADHD (n = 23), ASD+ (with ADHD symptoms, n = 23) and neurotypical controls (NTC, n = 28). All participants completed two tests: face encoding and retrieving task and Wisconsin Card Sorting Test (WCST) for measuring face memory and EF, respectively. Results revealed that: compared with the NTC group, children with ASD- exhibited lower accuracy in both face encoding and retrieving, and participants with ASD+ showed lower accuracy only in the retrieving, whereas no differences were found among participants with ADHD. Moreover, in the ASD+ group, face encoding performance was correlated with response perseverative errors (RPE) and failure to maintain sets (FMS) of WCST; significantly, there were no group differences between ASD+ and NTC in these two indices. The transdiagnostic profiles indicated that comorbid ADHD symptoms could modulate the face encoding deficiency of ASD, which may be partially compensated by EF. Shared and distinct intervention strategies to improve social cognition are recommended for children undergoing treatment for each condition

Susceptibility of Chinese grapes to grape phylloxera

Research Note

Effects of Pollen Typhae Total Flavone On β-Arrestin-2/SRC/ AKT signaling in adipose tissues of Type 2 diabetic rats

Background: Pollen Typhae total flavone (PTF), the extract from Pollen Typhae, a Chinese herbal medicine,  has been reported to improve insulin resistance in type 2 diabetic rats, but the potential mechanisms keep unclear.Materials and Methods: Type 2 diabetic model rats were induced by high-fat diet and low-dose  streptozotocin, and then were administered PTF by intragastrical gavage. After treatment for 4 weeks, insulin  receptor-β level in adipose tissues was determined by ELISA, and the protein expression was analyzed by  western blotting.Results: Administration of PTF increased insulin receptor-β level and enhanced β-arrestin-2 protein expression  in adipose tissues of type 2 diabetic rats. Although having no effect on the protein expression of Src  or Akt, PTF promoted phosphorylation of Src at Tyr416 and Akt at Ser473.Conclusion: The results indicate that PTF has beneficial effects on the β-arrestin-2/Src/Akt signaling in  adipose tissues of type 2 diabetic rats, implying the underlying mechanisms of PTF in ameliorating insulin  resistance.Key words: Chinese medicine, type 2 diabetes, signal transduction, insulin resistance, β-arrestin-