The effect of grana and inter-grana components of chloroplasts on green light transmission: A preliminary study

In this paper we simulate for the first time the propagation of green light through grana and inter-grana components of chloroplasts. Those components are nano-metric structures and thus regular estimation of the propagation of light cannot be exact without taking into account diffraction effects. The numerical investigation presented in this paper solves Maxwell wave equation using the finite-difference time-domain (FDTD) numerical approach to analyze the propagation of light through a chloroplast model.     

Common-path phase-shifting digital holographic microscopy: A way to quantitative phase imaging and superresolution

We present an experimental setup useful for complex amplitude evaluation and phase image quantification of three-dimensional (3-D) samples in digital holographic microscopy (DHM). It is based on a common-path interferometric configuration performed by dividing the input plane in two contiguous regions and by placing a translation grating near to the Fourier plane. Then, complex amplitude distribution of the sample under test is recovered with phase-shifting standard method obtained by moving the grating using a linear motion stage. Some experimental results of an USAF resolution test are presented for different numerical aperture (NA) microscope lenses. In a second part, the proposed setup is tested under superresolution purposes. Based on the object’s spectrum shift produced by off-axis illumination, we use time multiplexing to generate a synthetic aperture enlargement that improves the final image resolution. Experimental results for the case of a biosample (human red blood cells) and a commercial low NA microscope lens validates the suggested superresolution approach.     

New Developments in Activation Analysis for Material and Environmental Sciences

Activation analysis in general and mainly reactor neutron activation analysis (NAA) has been used extensively for measuring trace elements in high purity materials, particularly semiconductor materials. The advantages of NAA in determination of trace elements differ from one semiconductor material to another. For all of them the inherent properties of activation analysis especially those of non contamination with the reagents, low blanks and high sensitivity are the reasons for the choice of NAA as the main analytical procedure. These inherent properties are essential for analysis of high-purity materials where concentrations of ppb's and sub ppb's have to be measured. NAA is specially suitable for the determination of trace elements in silicon due to the very short lived very low activity induced by neutron reaction in silicon. This enables easy instrumental (i.e. without chemical separations) determination of trace elements in silicon. In the HFR reactor at Peten, Netherlands, a special facility was constructed for irradiation of silicon samples of Philips, in which silicon wafers of up to 15 cm diameter can be irradiated with 4 × 10¹³n. cm^?2. sec^?1 and the irradiation is done for 72–96 hours. using large Ge(Li) detectors (100 to 150cc) and long counting time (8–16 hours) they measured 22 elements in concentrations below ppb and 10 others between ppb and 300 ppm. Trace elements in germanium have been determined both instrumentally after very long decay time (100 days) or after short decay time removing the activities from the matrix by chemical separation. Trace elements in GaAs are determined only after chemical separtion. Several other semiconductor material such as Sc, Te, GaP and CuInS₂ were also determined by NAA. Some trace elements cannot be determined by neutron activation. Carbon, nitrogen and oxygen are determined by activation with protons, alphas or ³He particles. Boron and hydrogen are determined by prompt emission induced by charged particle activation, which gives not only the total concentration but also the depth profile. Carbon, nitrogen, oxygen and phosphorus were also determined by prompt proton activation analysis. The environmental samples studied by activation analysis can be divided into three categories: atmospheric aerosols, water samples and solid wastes. NAA of atmospheric aerosols have been used for their posible toxicological hazards, their source identification and for studies of atmospheric transport processes.     

A non-geometric shelling of a 3-polytope

We describe a shelling of the octahedron inE ³ which cannot be realized in the conventional geometric way.     

Nonoscillation and disconjugacy of systems of linear differential equations

The differential equations under consideration are of the form $\text{dx}\text{dt}\text{= A(t)x}$, (1) where A(t) is a piecewise continuous real n × n matrix on a real interval α, and the vector x = (x₁,…,x_n) is continuous on α. The equation is said to be nonoscillatory on α if every nontrivial real solution vector x has at least one component x_k which does not vanish on α.The principal concern of this paper is the derivation of conditions, expressed in terms of various norms of A, which guarantee the nonoscillation of (1) in a given interval.     

μ+ relaxation correlated with susceptibility in the van‐Vleck paramagnet PrIn3

A previously unobserved increase of the magnetic susceptibility in PrIn₃ at low temperatures is reported. The increase is shown to correlate nicely with a large increase in the transverse μSR depolarization rate. Evidence supports the conclusion that both phenomena are related to some degree of atomic disorder in the structure, and an associated strong Pr CEF level changes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pericyclic organometallic reactions. Cycloaddition reactions of (η-cycloheptatriene)Ru(CO)3. Crystal structure of tricarbonyl[(2,3,4,9-η)-bicyclo[4.2.1]non-2-ene-4,9-diyl-7,7,8,8-tetracarbonitrile]ruthenium

(η⁴-Cycloheptatriene)Ru(CO)₃ reacts with tetracyanoethylene (TCNE), 4-phenyltriazoline-3,5-dione (PTAD) and (carbomethoxy)maleic anhydride (CMA) to give stable 3 + 2 σ,π-allylic adducts. The 3 + 2 adduct with TCNE equilibrates via a [4,4]-sigmahaptotropic rearrangement with the less stable 6 + 2 adduct, which decomposes under the reaction conditions to the demetallated 6 + 2 adduct. It is concluded that σ,π-allylic adducts are in general more stable than their isomeric η⁴-π counterparts. The structure of the 3 + 2 TCNE adduct was determined by a single-crystal X-ray diffraction study.     

An ion mobility spectrometry/mass spectrometry (IMS/MS) study of the site of protonation in anilines

Ion mobility spectrometry (IMS) and IMS/MS techniques were used to differentiate between nitrogenprotonated and carbon-protonated anilines, both of which coexist under the conditions of the IMS. Analysis of the results led to the conclusion that the former species had lower mobilities than the latter. This was attributed mainly to charge delocalization in the ring-protonated species, which results in a weaker interaction with the drift gas molecules. Furthermore,meta-alkyl substitution enhanced ring protonation, while in 2-chloroaniline the nitrogenprotonated species was predominant, as expected.     

Kinetics of radiation-induced abstraction of hydrogen atoms by CCl3 radicals in the liquid phase: 2,3-dimethylbutane

The kinetics of the gamma-radiation induced free radical reactions in carbon tetrachloride solutions of 2,3-dimethylbutane (DMB) were studied in the temperature range 32–118 °C. The kinetics of the following reactions were measured: and the following rate constants expression was obtained: . The activation energy and the A factor obtained are in good agreement with the values obtained at the gaseous phase, considering the activation energy for self-diffusion of CCl₄.