Prompt gamma cold neutron activation analysis applied to biological materials

Summary Cold neutrons at the external neutron guide laboratory (ELLA) of the KFA Jülich are used to demonstrate their profitable application for multielement characterization of biological materials. The set-up and experimental conditions of the Prompt Gamma Cold Neutron Activation Analysis (PGCNAA) device is described in detail. Results for C, H, N, S, K, B, and Cd using synthetic standards and the “ratio” technique for calculation are reported for several reference materials and prove the method to be reliable and complementary with respect to the elements being determined by INAA. IAEA fellow at the KFA from 6. 3. 91 to 2. 9. 91 on contract No. VIE/9016R.     

A laser desorption fourier transform mass spectrometric study of dimethyl 8-acetyl-3,7,12,17-tetramethylporphyrin-2,18-dipropanoate

Laser desorption Fourier transform ion cyclotron resonance positive- and negative-ion mass spectra are presented for dimethyl 8-acetyl-3,7,12,17-tetramethylporphyrin-2,18-dipropanoate. The 248-nm laser ionization thresholds for both positive and negative ions are observed to be about 2.5 MW cm^?2. The M⁺˙ molecular ion is assigned to the base peak in the low-power spectra whereas it is the M^?˙ ion for the corresponding anion spectra. Increased intensities of [M + H]⁺ and [M ? H]^? are observed with increased laser fluences of up to 38 MW cm^?2. At high laser powers the negative-ion results reveal that a series of carbon-nitrogen cumulene and polyacetylene cluster ions are formed. Laser evaporation/multiphoton ionization/ and thermal evaporation/electron impact ionization/collision-induced dissociation experiments carried out on the porphyrin M⁺˙ and [M + H]⁺ ions over a range of translational kinetic energies and delay times after acceleration are compared and used to obtain mechanistic and structural information. In contrast to the electron impact experiments, which show only side-chain cleavage, the laser-based collision-induced dissociation experiments reveal that, in addition to side-chain cleavage, it is possible to cleave the porphyrin ring to various extents depending on the ion translational energy selected.     

Synthesis of Jasminaldehyde by Solid-Liquid Phase Transfer Catalysis Without Solvent,Under Microwave Irradiation

α-n-amylcinnamaldehyde (jasminaldehyde) was obtained with 82 % yield by solid-liquid phase transfer catalysis without solvent within 3 days at room temperature. By use of domestic microwave irradiation, the same yield was obtained within 1 minute at a power of 600 W.     

Graphene Nanocomposites Based Electrochemical Sensing Platform for Simultaneous Detection of Multi-drugs

Three reduced graphene oxide nanocomposites were employed to achieve the simultaneous electrochemical determination of multi-drugs including acetaminophen (ACTM), carbendazim (CB) and ciprofloxacin (CFX). All nanocomposite modified electrodes showed improved current responses for three drugs. Notably cauliflower-like platinum nanoparticles decorated reduced graphene oxide modified electrode (or Pt−RGO/GCE) exhibited the best performance in terms of electrochemical stability. Using Pt−RGO/GCE, the linear detect ranges of 30–120 μM, 25–115 μM and 10–25 μM, and detection limit values of 3.49, 2.96, and 1.53 μM were achieved for ACTM, CB and CFX respectively. The electrode was further used for the successful determination of above drugs in tap and river water using differential pulse voltammetry. From the obtained results, we believe that Pt-RGO/GCE is highly promising for the fabrication of robust electrochemical sensors for simultaneously determining ACTM, CB and CFX or similar types of drugs in the future.     

Analysis of macro-constituents in steels by PGAA

The determinatin of the concentration of major steel forming elements in 2–5 g steel samples by PGAA and reference to synthetic standard or single comparator is presented. The relative standard deviation is approximately 5%. The analysis time is about 60 min per sample.     

Simple and rapid synthesis of ternary polyaniline/titanium oxide/graphene by simultaneous TiO<Subscript>2</Subscript> generation and aniline oxidation as hybrid materials for supercapacitor applications

This paper reports a simple methodology for the synthesis of a polyaniline/titanium oxide/graphene hybrid (Pani/TiO₂/GN) using a simple methodology, and their application as a supercapacitor electrode material for energy storage. The Pani/TiO₂/GN hybrid was prepared by a simple approach by simultaneous generation of Pani and TiO₂ in situ from aniline and titanium iso-propoxide, respectively, in the presence of GN under ice bath conditions. The incorporation of GN improved the electrical conductivity of Pani and helped to decrease the charge transfer resistance, whereas TiO₂ generation by an in situ method increased the surface area considerably and enhanced the capacitance of the Pani/TiO₂/GN hybrid. TEM showed that Pani and TiO₂ were well incorporated and coated on the GN successfully. The shift of the peaks in the FTIR spectrum and XRD pattern of the Pani/TiO₂/GN hybrid compared to their pure counterparts suggested that TiO₂ and Pani had been perfectly coated on the GN, and there was a strong interaction among Pani, GN, and TiO₂ particles. The electrochemical performance of the as-prepared Pani/TiO₂/GN hybrid electrode showed a high specific capacitance of 403.2 F g^?1 at a current density of 2 A g^?1 and excellent cycling stability for up to 1000 cycles. This suggested that the effective incorporation of GN and TiO₂ into Pani and the high surface area could simultaneously increase the electrochemical capacitance and cyclic stability of the Pani/TiO₂/GN hybrid, leading to superior electrochemical performance.

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Graphical abstract The electrochemical performance of as-prepared Pani/TiO₂/GN hybrid electrode showed a high specific capacitance of 403.2 F g^?-1 at a current density of 2 A g^?-1 and excellent cycling stability for up to 1000 cycles. This suggested that the effective incorporation of GN and TiO₂ into Pani and the high surface area could simultaneously increase the electrochemical capacitance and cycle stability of the Pani/TiO₂/GN hybrid, leading to superior electrochemical performance.

     

Losses of optical multimode strip-waveguides made by thick film technology

Loss measurements on straight and curved multimode strip-waveguides made from photosensitive sheets by a photolithographic process are reported. The cross section of the waveguides vary from 20 μm × 50 μm to 100 μm × 100 μm. The loss is detected by measuring the light scattered out of the waveguide. Waveguides fabricated by a modified technology are compared to conventional ones at wavelengths of 0.633 μm and 0.83 μm. Using the modified technology losses of 2 dB/cm at λ = 0.83 μm have been measured for both straight and curved (radius 30 mm) guides.     

Detection of Alzheimer's tau protein using localised surface plasmon resonance-based immunochip

In this study, we present the detection of tau protein, at room temperature, using a multi-spot localised surface plasmon resonance (LSPR)-based immunochip. To the best of our knowledge, this is the first report of an immunochip for tau protein. The detection method includes fabrication of a gold-capped nanoparticle LSPR chip, formation and functionalisation of a self-assembled monolayer (SAM), immobilisation of a suitable linker, effective blocking of non-specific adsorption, immobilisation of a monoclonal anti-tau antibody (tau-mAb), and finally, the optimum conditions for the immuno-reaction between tau-mAb and the antigen were determined. The method has a high performance, enables detection of tau at 10pg/mL, lower than the cut-off value of 195pg/mL (for AD) for tau protein in cerebral spinal fluid (CSF). Further, we demonstrated selectivity of the technique by showing that the introduction of bovine serum albumin (BSA), perhaps the most abundant protein component in serum and CSF, does not interfere with the detection of tau. This method also offers a potential platform for studying tau interactions with other proteins and/or potential drug candidates and could also be easily adapted for detecting phosphorylated tau and other AD biomarkers.     

The Effect of Physical-Chemical Nature of UHMWPE and PPS Thermoplastic Matrices on the Formation of Mechanical and Tribological Properties of their Carbon Fiber Filled Composites

Russian Physics Journal - The effect of carbon fiber dimensions on mechanical and tribological properties of the composites based on two thermoplastic matrices of different physical-chemical nature...