Polar Plot Representation for Frequency-Domain Analysis of Fluorescence Lifetimes

We present applications of polar plots for analyzing fluorescence lifetime data acquired in the frequency domain. This graphical, analytical method is especially useful for rapid FLIM measurements. The usual method for sorting out and determining the underlying lifetime components from a complex fluorescence signal is to carry out the measurement at multiple frequencies. When it is not possible to measure at more than one frequency, such as rapid lifetime imaging, specific features of the polar plot analysis yield valuable information, and provide a diagnostic visualization of the participating fluorescent species underlying a complex lifetime distributions. Data are presented where this polar plot presentation is useful to derive valuable, unique information about the underlying component distributions. We also discuss artifacts of photolysis and how this method can also be applied to samples where each fluorescence species shows a continuous distribution of lifetimes. Polar plots of frequency-domain data are commonly used for analysis of dielectric relaxation experiments (Cole–Cole plots), which have proved to be exceptionally useful in that field for decades. We compare this analytical tool that is well developed and extensively used in dielectric relaxation and chemical kinetics to fluorescence measurements.     

Utilization of α-olefins obtained by pyrolysis of waste high density polyethylene to synthesize α-olefin-succinic-anhydride based cold flow improvers

A new route of utilization of α-olefin rich hydrocarbon fractions obtained by waste polymer pyrolysis was investigated. α-olefin-succinic-anhydride intermediate-based pour point depressant additives for diesel fuel were synthesized, in which reactions needed α-olefins were obtained by pyrolysis of waste high-density polyethylene (HDPE). Fraction of α-olefins was produced by the de-polymerization of plastic waste in a tube reactor at 500℃ in the absence of catalysts and air. C_17~22 range of mixtures of olefins and paraffins were separated for synthesis and then, these hydrocarbons were reacted with maleic-anhydride (MA) for formation of α-olefin-succinic-anhydride intermediates. The olefin-rich hydrocarbon fraction contained approximately 60% of olefins, including 90%~95% α-olefins. Other intermediates were produced in the same way by using commercial C₂₀ α-olefin instead of C_17~22 olefin mixture. The two different experimental intermediates with number average molecular weights of 1850g/mol and 1760g/mol were reacted with different alcohols: 1-butanol, 1-hexanol, 1-octanol, i-butanol, and c-hexanol to produce their ester derivatives. The synthesized ten experimental pour point depressants were added in different concentrations to conventional diesel fuel, which had no other additive content before. The structure and efficiency of experimental additives were followed by different standardized and non-standardized methods. Results showed that the experimental additives on the basis of the product of waste pyrolysis were able to decrease not only the pour but also the cloud point and cold filter plugging point (CFPP) of diesel fuel, whose effects could be observed even if the concentration of additives was low. Furthermore, all additives had anti-wear and anti-friction effects in diesel fuel.     

Deposition of continuous nickel shells on polymer microspheres

Anisotropic conductive adhesives (ACAs) are widely used as interconnect materials in the manufacturing of LCD screens. To be integrated in a broader range of applications, several technical and economical issues still need to be addressed. Encapsulating the polymer particles within continuous, compact, and adhering metallic conductive shells is one of these challenges. This work describes a method for depositing nickel layers with different thickness (30-120nm) onto monosized polymer particles. The novelty of the approach consists in modifying the surface of polymer particles with linear polymeric amines. We show that by increasing amine chain length the structure and adhesion of deposited nickel shell are significantly improved. The effect of key parameters of the electroless Ni plating are discussed and illustrated.     

An alternating direction scheme on a nonuniform mesh for reaction-diffusion parabolic problems

In this paper we develop a numerical method for two-dimensionaltime-dependent reaction-diffusion problems. This method, whichcan immediately be generalized to higher dimensions, is shownto be uniformly convergent with respect to the diffusion problems.This method, which can immediately be generalized to higherdimensions, is shown to be uniformly convergent with respectto the diffusion parameter.     

Effects of gamma irradiation on solid and lyophilised phospholipids

The effects of gamma irradiation (25 kGy) as a sterilisation method for phospholipids (distearoylphosphatidylcholine and distearoylphosphatidylglycerol) were investigated. ³¹P-NMR revealed minor chemical degradation of the phospholipids but lower dynamic viscosity and pseudoplasticity, lower turbidity, higher diffusion constant, smaller size, more negative zeta potential and changes in the phase transition behaviour of the subsequently produced liposomes were observed. The observed changes could to some extent be explained by the irradiation-induced degradation products (distearoylphosphatidic acid, fatty acids, lysophospholipids).     

Transition metal-catalyzed synthesis of pyrroles from dienyl azides

A range of 2,5-disubstituted and 2,4,5-trisubstituted pyrroles can be synthesized from dienyl azides at room temperature using catalytic amounts of ZnI2 or Rh2(O2CC3F7)4.     

Properties of microfluidic turbulent mixing revealed by fluorescence lifetime imaging

We present a new method of measurement based on fluorescence lifetime imaging that reveals molecular-scale details of the mixing process in a continuous-flow turbulent microfluidic reactor. Our data provide a glimpse of the cascade to the minimal eddy size, followed by rapid diffusion involving the smallest eddies for final mixing.     

The EIGER detector for low‐energy electron microscopy and photoemission electron microscopy

EIGER is a single‐photon‐counting hybrid pixel detector developed at the Paul Scherrer Institut, Switzerland. It is designed for applications at synchrotron light sources with photon energies above 5 keV. Features of EIGER include a small pixel size (75 µm × 75 µm), a high frame rate (up to 23 kHz), a small dead‐time between frames (down to 3 µs) and a dynamic range up to 32‐bit. In this article, the use of EIGER as a detector for electrons in low‐energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) is reported. It is demonstrated that, with only a minimal modification to the sensitive part of the detector, EIGER is able to detect electrons emitted or reflected by the sample and accelerated to 8–20 keV. The imaging capabilities are shown to be superior to the standard microchannel plate detector for these types of applications. This is due to the much higher signal‐to‐noise ratio, better homogeneity and improved dynamic range. In addition, the operation of the EIGER detector is not affected by radiation damage from electrons in the present energy range and guarantees more stable performance over time. To benchmark the detector capabilities, LEEM experiments are performed on selected surfaces and the magnetic and electronic properties of individual iron nanoparticles with sizes ranging from 8 to 22 nm are detected using the PEEM endstation at the Surface/Interface Microscopy (SIM) beamline of the Swiss Light Source.     

Sulphur compounds in the kerosine boiling range of middle east distillates Occurrence of a bicyclic thiophene and a thienyl sulphide

A bicyclic thiophene, 1,4,4-trimethyl-4,5,6,7-tetrahydroisothianaphthene, and a thienyl sulphide, methyl 3, 4, 5-trimethyl-2-thienyl sulphide, have been isolated from a concentrate of sulphur compounds obtained in the refining of a Middle East kerosine. The structures of these compounds have been established.     

Optimisation of variables for studying dilepton transverse momentum distributions at hadron colliders

In future measurements of the dilepton (Z/γ ^∗) transverse momentum, Q _T , at both the Tevatron and LHC, the achievable bin widths and the ultimate precision of the measurements will be limited by experimental resolution rather than by the available event statistics. In a recent paper the variable a _T , which corresponds to the component of Q _T that is transverse to the dilepton thrust axis, has been studied in this regard. In the region, Q _T < 30 GeV, a _T has been shown to be less susceptible to experimental resolution and efficiency effects than the Q _T . Extending over all Q _T , we now demonstrate that dividing a _T (or Q _T ) by the measured dilepton invariant mass further improves the resolution. In addition, we propose a new variable, f_h^*\phi _{\rm \eta }^{*}, that is determined exclusively from the measured lepton directions; this is even more precisely determined experimentally than the above variables and is similarly sensitive to the Q _T . The greater precision achievable using such variables will enable more stringent tests of QCD and tighter constraints on Monte Carlo event generator tunes.