Selective determination of norepinephrine in the presence of ascorbic and uric acids using an ultrathin polymer film modified electrode

This paper reports the selective determination of norepinephrine (NEP) in the presence of very important interferences, ascorbic acid (AA) and uric acid (UA) using electropolymerized film of 2-amino-1,3,4-thiadiazole (p-ATD) modified glassy carbon (GC) electrode in 0.20 M phosphate buffer solution (pH 5.0). The bare GC electrode does not separate the voltammetric signals of AA, NEP and UA. However, p-ATD modified GC electrode not only resolved the voltammetric signals of AA, NEP and UA with potential differences of 150 and 130 mV between AA–NEP and NEP–UA, respectively but also dramatically enhanced the oxidation peak currents of them when compared to bare GC electrode. The modified electrode showed an excellent selectivity towards NEP even in the presence of 100-fold excess of AA and UA. The amperometric current was linearly increased from 40 nM to 25 μM for NEP and the lowest detection limit was found to be 0.17 nM (S/N = 3). The practical application of the modified electrode was demonstrated by determining NEP in norepinephrine hydrochloride injection.     

Daily evapotranspiration prediction using gradient boost regression model for irrigation planning

The Journal of Supercomputing - Appropriate irrigation planning with reference evapotranspiration (ETo) plays an important role in managing the water resources for agriculture. This paper presents...     

Salinity Stress Alters the Secondary Metabolic Profile of M. sativa,M. arborea and Their Hybrid (Alborea)

Increased soil salinity, and therefore accumulation of ions, is one of the major abiotic stresses of cultivated plants that negatively affect their growth and yield. Among Medicago species, only Medicago truncatula, which is a model plant, has been extensively studied, while research regarding salinity responses of two important forage legumes of Medicago sativa (M. sativa) and Medicago arborea (M. arborea) has been limited. In the present work, differences between M. arborea, M. sativa and their hybrid Alborea were studied regarding growth parameters and metabolomic responses. The entries were subjected to three different treatments: (1) no NaCl application (control plants), (2) continuous application of 100 mM NaCl (acute stress) and (3) gradual application of NaCl at concentrations of 50-75-150 mM by increasing NaCl concentration every 10 days. According to the results, M. arborea maintained steady growth in all three treatments and appeared to be more resistant to salinity. Furthermore, results clearly demonstrated that M. arborea presented a different metabolic profile from that of M. sativa and their hybrid. In general, it was found that under acute and gradual stress, M. sativa overexpressed saponins in the shoots while M. arborea overexpressed saponins in the roots, which is the part of the plant where most of the saponins are produced and overexpressed. Alborea did not perform well, as more metabolites were downregulated than upregulated when subjected to salinity stress. Finally, saponins and hydroxycinnamic acids were key players of increased salinity tolerance.     

Characterisation of heterogeneous microstructure in large forged products using nonlinear ultrasonic method

ABSTRACT

A comparative study between the ultrasonic attenuation and the nonlinearity is presented for the characterisation of microstructure in large dimension forgings. Results are provided for two austenitic stainless steel forgings of AISI type 304L with a diameter 200?mm, where microscopic observations reveal abnormal grain growth near the surface of one of the forgings. Frequency dependence of the nonlinearity parameter is used to discern variations in grain size in these forgings more precisely than attenuation measurements. The distribution of grain size is shown to have a significant influence on the nonlinearity parameter. Relative changes in the nonlinearity parameter with applied frequency were correlative with the microstructural variations in both the forgings.     

Physicochemical studies on the inhibitive properties of a 1,2,4-triazole Schiff’s base,HMATD, on the corrosion of mild steel in hydrochloric acid

The efficiency of 4-(4-hydroxy-3-methoxy benzyledene amino)-4-H-1,2,4-triazole-3, 5-dimethanol, HMATD, as corrosion inhibitor for mild steel in 0.5 M HCl has been determined by weight loss measurements and electro analytical methods. The influence of various parameters such as temperature, inhibitor concentration on the efficiency has been studied. The electrochemical impedance spectroscopic measurements revealed the inhibition action of HMATD by reducing the charge transfer through metal solution interface. Polarization curves indicate the mixed type behaviour of HMATD. The inhibitor molecule functions by blocking the active sites on metal surface by adsorption and which obeys the Langmuir adsorption isotherm. Various kinetic and thermodynamic parameters have also been calculated.     

Off-Chip Skew Measurement and Compensation Module (SMCM) Design for Built-Off Test Chip

Skew calibration and compensation are critical ATE features for reliable functional test, particularly for applications such as memory chips since most mainstream memories use a source-synchronous interface. This paper presents a new Skew Measurement and Compensation Module (SMCM) design for off-chip skew calibration from Time Domain Reflectometry (TDR) measurements. It consists of coarse and fine parts which enable the circuit to detect a large skew range with high resolution. Circuit complexity is reduced through use of the proposed automatic edge detection method which controls coarse/fine operations. We also present skew compensation circuits which can de-skew off-chip signals based on the skew calibration. The SMCM occupies a small area, making it suitable for implementation in a Built-Off Test (BOT) chip. The circuits were implemented using a 130 nm technology in a Built-Off Test Interface (BOTI) developed for 800 Mbps DDR2 memory functional test.     

Segmentation of weather radar image based on hazard severity using RDE: reconstructed mutation strategy for differential evolution algorithm

Weather describes the condition of our atmosphere during a specific period of time, and climate represents a composite of day to day weather over longer period of time. Climatology attempts to analyze and explain the impact of climate so that the society can plan accordingly. Climatology analysis is often done on radar images representing various climatic conditions. These images contain varying scale of severity for any specific climatic parameter of study. The climatologists often find it convenient to analyze climatic conditions if tools are available to segment the weather images based on the severity scale which is represented by different colors. Segmentation of the weather radar image is also used for automated analysis of weather conditions. Differential evolution (DE) approach instead is used for fast selection of optimal threshold. In present paper, we have applied DE with multilevel thresholding for weather image segmentation which results in minimum computational time and excellent image quality. A new mutation strategy for DE named reconstructed differential evolution (RDE) strategy is suggested for better performance over image segmentation. Using fuzzy entropy and RDE for multilevel thresholding provides better results in comparison with last suggested methods.

     

Adsorption thermodynamics and kinetics study for the self-assembly of 1,8,15,22-tetraaminophthalocyanatocobalt(II) on glassy carbon surface

Spontaneous adsorption of 1,8,15,22-tetraaminophthalocyanatocobalt(II) (4α-Co^IITAPc) on glassy carbon (GC) electrode leads to the formation of a stable self-assembled monolayer (SAM). Since the SAM of 4α-Co^IITAPc is redox active, its adsorption on GC electrode was followed by cyclic voltammetry. SAM of 4α-Co^IITAPc on GC electrode shows two pairs of well-defined redox peaks corresponding to Co^III/Co^II and Co^IIIPc⁻¹/Co^IIIPc⁻². The surface coverage (Γ) value, calculated by integrating the charge under Co^II oxidation, was used to study the adsorption thermodynamics and kinetics of 4α-Co^IITAPc on GC surface. Cyclic voltammetric studies show that the adsorption of 4α-Co^IITAPc on GC electrode has reached the saturation coverage (Γ_s) within 3 h. The Γ_s value for the SAM of 4α-Co^IITAPc on GC electrode was found to be 2.37 × 10⁻¹⁰ mol cm⁻². Gibbs free energy (ΔG_ads) and adsorption rate constant (k_ad) for the adsorption of 4α-Co^IITAPc on GC surface were found to be −16.76 kJ mol⁻¹ and 7.1 M⁻¹ s⁻¹, respectively. The possible mechanism for the self-assembly of 4α-Co^IITAPc on GC surface is through the addition of nucleophilic amines to the olefinic bond on the GC surface in addition to a meager contribution from π stacking. The contribution of π stacking was confirmed from the adsorption of unsubstituted phthalocyanatocobalt(II) (CoPc) on GC electrode. Raman spectra for the SAM of 4α-Co^IITAPc on carbon surface shows strong stretching and breathing bands of Pc macrocycle, pyrrole ring and isoindole ring. Raman and CV studies suggest that 4α-Co^IITAPc is adopting nearly a flat orientation or little bit tilted orientation.     

Photoelectrochemical Study of Nanostructured ZnO Thin Films for Hydrogen Generation from Water Splitting

Photoelectrochemical cells based on traditional and nanostructured ZnO thin films are investigated for hydrogen generation from water splitting. The ZnO thin films are fabricated using three different deposition geometries: normal pulsed laser deposition, pulsed laser oblique‐angle deposition, and electron‐beam glancing‐angle deposition. The nanostructured films are characterized by scanning electron microscopy, X‐ray diffraction, UV‐vis spectroscopy and photoelectrochemical techniques. Normal pulsed laser deposition produces dense thin films with ca. 200 nm grain sizes, while oblique‐angle deposition produces nanoplatelets with a fishscale morphology and individual features measuring ca. 900 by 450 nm on average. In contrast, glancing‐angle deposition generates a highly porous, interconnected network of spherical nanoparticles of 15–40 nm diameter. Mott‐Schottky plots show the flat band potential of pulsed laser deposition, oblique‐angle deposition, and glancing‐angle deposition samples to be ?0.29, ?0.28 and +0.20 V, respectively. Generation of photocurrent is observed at anodic potentials and no limiting photocurrents were observed with applied potentials up to 1.3 V for all photoelectrochemical cells. The effective photon‐to‐hydrogen efficiency is found to be 0.1%, 0.2% and 0.6% for pulsed laser deposition, oblique‐angle deposition and glancing‐angle deposition samples, respectively. The photoelectrochemical properties of the three types of films are understood to be a function of porosity, crystal defect concentration, charge transport properties and space charge layer characteristics.