Fluorescence Assay Based on Aptamer-Quantum Dot Binding to <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> Spores

A novel assay was developed for the detection of Bacillus thuringiensis (BT) spores. The assay is based on the fluorescence observed after binding an aptamer-quantum dot conjugate to BT spores. The in vitro selection and amplification technique called SELEX (Systematic Evolution of Ligands by EXponential enrichment) was used in order to identify the DNA aptamer sequence specific for BT. The 60 base aptamer was then coupled to fluorescent zinc sulfide-capped, cadmium selenide quantum dots (QD). The assay is semi-quantitative, specific and can detect BT at concentrations of about 1,000 colony forming units/ml.     

Temperature dependence of dark current-voltage characteristics of <Emphasis Type="Italic">n</Emphasis>InSb-<Emphasis Type="Italic">n</Emphasis>PbTe-<Emphasis Type="Italic">n</Emphasis>CdTe isotype structure

The temperature dependence of dark current-voltage characteristics of an nInSb-nPbTe-nCdTe structure is investigated. It is shown that in the temperature range from 115 K to 125 K an energy barrier exists for charge carriers through the InSb layer, which is strictly connected with different temperature dependences of electron concentrations in nInSb and nPbTe.     

Laser-beam-induced current in two-dimensional <Emphasis Type="Italic">n-p-n</Emphasis>-structures

Appearance of a transverse photocurrent at local excitation, by an optical beam, of the surface of n-p-n-structure realized on the basis of a two-dimensional electron gas is studied theoretically. It is shown that the magnitude and sign of the photocurrent depend on the coordinate of the center of light spot. Conditions of linearity of this dependence are found demonstrating the suitability of two-dimensional bipolar structures for use in position-sensitive detectors with high spatial resolution.     

Electronic energy of the <Superscript>1</Superscript><Emphasis Type="Italic">L</Emphasis><Subscript>a</Subscript> level of supersonic jet-cooled indole

The dependence of the fluorescence polarization degree on frequency upon excitation into the first and second electronic bands of jet-cooled indole has been studied. A structured band consisting of a number of lines rather than a single line has been recorded in the spectral range of the electronic ¹A′-¹L_a-transition. The appearance of the lines is interpreted as the result of nonadiabatic vibronic interaction between the electronic ¹L_a-state and vibronicl states of the indole molecule ¹L_b-level. The energy of the unperturbed electronic ¹L_a-level and the orientation of dipole moments near the ¹A′-¹L_a-transition have been found. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 319–323, May–June, 2008.     

Mechanism of complexing of chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> and tetra(<Emphasis Type="Italic">p</Emphasis>-carboxyphenyl)porphyrin with malate dehydrogenase

The mechanism of complexing of the tetrapyrrole-nature photodynamic sensitizers chlorin e₆ and tetra(p-carboxyphenyl)porphyrin (TCPP) with the Krebs-cycle enzyme malate dehydrogenase (MDG) has been investigated by spectral-luminescence methods. It is shown that each subunit entering into the composition of the MDG dimer molecule forms an equilibrium complex with one dye molecule. However, if the sites of bonding of TCPP on a protein molecule are independent, the MDG-chlorin e₆ complex has a negative cooperativity since after the dye is incorporated into the first subunit of the macromolecule, its penetration to the second subunit becomes difficult. This is explained by the fact that conformation transformations, arising as a result of the incorporation of chlorin into one of the MDG subunits, are transferred to the site of its bonding on other MDG subunits through the intersubunit contacts of the enzyme. It has been established that photosensitizers compete with the hydrophobic fluorescent probe 8-aniline-1-naphthalenesulfonate (ANS) (whose position in the MDG macromolecule was described in detail in the literature) for the sites of bonding on the protein molecule, which allows the conclusion that TCPP and chlorin e₆ are localized in the catalytic domain of MDG. In this case, the sites of bonding of these dyes and the sites of bonding of nicotinamide-adenine dinucleotide, occupying the MDG domain that bonds coenzymes, do not interact with each other.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 111–118, January–February, 2005.     

Recent high-<Emphasis Type="Italic">p</Emphasis><Subscript><Emphasis Type="Italic">T</Emphasis></Subscript> results from STAR

We present selected recent results of multi-hadron correlation measurements in azimuth and pseudorapidity at intermediate and high p _T in Au+Au collisions at , from the STAR experiment at RHIC. At intermediate p _T , measurements are presented that attempt to determine the origin of the associated near-side (small Δφ) yield at large pseudo-rapidity difference Δη that is found to be present in heavy ion collisions. In addition, results are reported on new multi-hadron correlation measures at high-p _T that use di-hadron triggers and multi-hadron cluster triggers with the goal to constrain the underlying jet kinematics better than in the existing measurements of inclusive spectra and di-hadron correlations.     

Lifetime of nonequilibrium charge carriers in the base of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">n</Emphasis>-junction semiconductor diode at arbitrary injection levels

In the approximation of exponential distribution of nonequilibrium charge carriers in the base of semiconductor p-n-junction diode a formula is obtained for lifetime calculation, which is valid at arbitrary injection levels. The lifetime is determined via measurements of only stationary characteristics of diodes (dc-CVC and low-frequency differential resistance). These characteristics, as well as the dependence of the barrier capacity on the reverse voltage, for determination of equilibrium concentration of carriers in the diode base, have been measured for D226B alloy diodes. The dependence of the lifetime of nonequilibrium carriers on the injection level, calculated from experimental data, agrees with the Shockley-Read theory of recombination; this agreement may be considered as a justification of assumptions made for lifetime calculation.     

Non-vacuum Bianchi types <Emphasis Type="Italic">I</Emphasis> and <Emphasis Type="Italic">V</Emphasis> in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>) gravity

In a recent paper (Sharif and Shamir in Class. Quantum Grav. 26:235020, 2009), we have studied the vacuum solutions of Bianchi types I and V spacetimes in the framework of metric f (R) gravity. Here we extend this work to perfect fluid solutions. For this purpose, we take stiff matter to find energy density and pressure of the universe. In particular, we find two exact solutions in each case which correspond to two models of the universe. The first solution gives a singular model while the second solution provides a non-singular model. The physical behavior of these models has been discussed using some physical quantities. Also, the function of the Ricci scalar is evaluated.     

Femtosecond laser ablation of neurons in <Emphasis Type="Italic">C</Emphasis>. <Emphasis Type="Italic">elegans</Emphasis> for behavioral studies

In this paper, the interaction between the inhomogeneous and anisotropic cloak covered infinitely long PEC circular cylinder and the parallel electric-line-source is investigated in detail. First, the permittivity and permeability tensors of the cloak are defined according to Pendry’s model, then the wave equation in the metamaterial cloak is derived; second, the far/near properties of the model are investigated, and using the boundary conditions the electromagnetic fields of the whole region are calculated analytically; finally, based on the analytical expressions, the electric fields of the whole region are demonstrated through numerical results which show the effects of invisibility. Finally, the effects of loss on the performance of the invisible cloak are investigated.     

Study of quark distribution amplitudes of 1<Emphasis Type="Italic">S</Emphasis> and 2<Emphasis Type="Italic">S</Emphasis> heavy quarkonium states

In this paper, the quark distribution amplitudes of 1S and 2S heavy quarkonium states are studied in terms of Gaussian-type wave functions. The transverse momenta p _⊥ integrals of the formulae for the decay constant are performed analytically. Then the quark distribution amplitudes are obtained. In addition, the ξ-moments are also calculated. After fixing the relevant parameters appearing in the quark distribution amplitude, the curves of the quark distribution amplitude for 1S and 2S heavy quarkonium states are plotted. Finally, the numerical results of this approach are compared with the other theoretical predictions.     

Local Resolvent Estimates for <Emphasis Type="Italic">N</Emphasis>-body Stark Hamiltonians

For an N-body Stark Hamiltonian , the resolvent estimate holds uniformly in with Re and Im , where , and is a compact interval. This estimate is well known as the limiting absorption principle. In this paper, we report that by introducing the localization in the configuration space, a refined resolvent estimate holds uniformly in with Re and Im . Dedicated to Professor Hideo Tamura on the occasion of his 60th birthday     

Calcium Ion-Induced Stabilization and Refolding of Agkisacutacin from <Emphasis Type="Italic">Agkistrodon Acutus</Emphasis> Venom Studied by Fluorescent Spectroscopy

Agkisacutacin isolated from the venom of Agkistrodon acutus is a coagulation factor IX / coagulation factor X-binding protein with marked anticoagulant- and platelet-modulating activities. Ca²⁺ ion-induced stabilization and refolding of Agkisacutacin have been studied by following fluorescent measurements. Ca²⁺ ions not only increase the structural stability of agkisacutacin against GdnHCl denaturation, but also induce its refolding. The GdnHCl-induced unfolding of the apo-agkisacutacin and the purified agkisacutacin is a single-step process with no detectable intermediate state. Ca²⁺ ions play an important role in the stabilization of the structure of agkisacutacin. Ca²⁺-stabilized agkisacutacin exhibits higher resistance to GdnHCl denaturation than the apo-agkisacutacin. It is possible to induce refolding of the unfolded apo-agkisacutacin merely by adding 1 mM Ca²⁺ ions without changing the concentration of the denaturant. The kinetic result of Ca²⁺-induced refolding provides evidences for that agkisacutacin consists of at least two refolding phases and the first phase of Ca²⁺-induced refolding should involve the formation of the compact Ca²⁺-binding site regions, and subsequently, the protein undergoes further conformational rearrangements to form the native structure.     

<Emphasis Type="Italic">q</Emphasis>-Analogue of Modified KP Hierarchy and its Quasi-Classical Limit

A string basis is constructed for each subalgebra of invariants of the function algebra on the quantum special linear group. By analyzing the string basis for a particular subalgebra of invariants, we obtain a “canonical basis” for every finite dimensional irreducible -module. It is also shown that the algebra of functions on any quantum homogeneous space is generated by quantum minors. Supported by the Australian Research Council and Chinese National Natural Science Foundation project number: 10471070     

Ferromagnetism and ferroelectricity in Eu<Emphasis Type="Italic">X</Emphasis> (<Emphasis Type="Italic">X</Emphasis> = <Emphasis Type="Italic">O</Emphasis>, <Emphasis Type="Italic">S</Emphasis>): pressure effects

Ferromagnetism and ferroelectricity in Eu monochalcogenides have been investigated by ab initio density functional theory in the DFT+U approach. Exchange interaction parameters and Curie temperatures under pressure are studied and discussed using Heisenberg Hamiltonian with first and second-nearest-neighbor interactions. The calculations showed that the hydrostatic pressure perfectly improves the Curie temperature (EuO: T _C = 175 K; EuS: T _C = 33.8 K) and in the other hand it cannot induce the spontaneous polarization (P _s ). The effect of uniaxial and biaxial pressure is also studied. Although the uniaxial strains slightly increases the Curie temperature, it ensures the ferrolectricity in these systems by producing a spontaneous polarization of the order of P _s (EuO) = 57.50 μC/cm² and P _s (EuS) = 42.86 μC/cm² with pressures of 5% and 4%, respectively. The search for new model systems is a necessity to better understand the physics related to multiferroïc materials and to consider possible applications.     

Energy and system dependence of high-<Emphasis Type="Italic">p</Emphasis><Subscript><Emphasis Type="Italic">T</Emphasis></Subscript> triggered two-particle near-side correlations

Previous studies have indicated that the near-side peak of high-p _T triggered correlations can be decomposed into two parts, the Jet and the Ridge. We present data on the yield per trigger of the Jet and the Ridge from d+Au, Cu+Cu and Au+Au collisions at GeV and 200 GeV and compare data on the Jet to PYTHIA 8.1 simulations for p+p. PYTHIA describes the Jet component up to a scaling factor, meaning that PYTHIA can provide a better understanding of the Ridge by giving insight into the effects of the kinematic cuts. We present collision energy and system dependence of the Ridge yield, which should help distinguish models for the production mechanism of the Ridge.     

Impurity photovoltaic effect in <Emphasis Type="Italic">p-i-n</Emphasis> structures of undoped GaAs

Photo-emf in the range hv = 0.76 ? 1.35 eV was found in p-i-n structures produced from undoped GaAs crystals with known parameters; the current sensitivities in the impurity and intrinsic (hv > 1.35 eV) regions were comparable. It was proven that the impurity photovoltaic effect results from EL2 and EL3 structural defects creating deep donor levels in the forbidden zone. Calculations were performed that justified the possibility of observing this effect on the investigated structures.     

Spectral-luminescent properties of chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> and malate dehydrogenase complexes

Spectral confirmation of the formation of stable equilibrium complexes (association constant K _as = 210⁶ M^–1) of the Krebs cycle enzyme — malate dehydrogenase (MDH) — and one of the promising photodynamic sensitizers — chlorin e ₆ — have been obtained. It is shown that the incorporation of dye molecules into the protein globule of dimeric MDH (each subunit of which contains 4 tryptophan amino acid residues, each binding one molecule of chlorin e ₆) is accompanied by quenching of the tryptophan fluorescence of the enzyme. However, despite the overlapping of the fluorescence spectra of tryptophanyls of MDH and the absorption spectrum of chlorin e ₆, the fluorescence quenching observed is not caused by singlet-singlet inductive-resonant transfer of energy from the donor to the acceptor. The conclusion has been drawn that the reason for the absence of energy transfer from tryptophanyls to the dye is the more effective intertryptophan migration of energy to one of the most longwave amino acid residues, the quenching of the luminescence of which occurs due to the reversible photoinduced transfer of an electron to chlorin e ₆ (formation of a complex with charge transfer). The formation of a complex with charge transfer between chlorin e ₆ (when it is excited) and one of the amino acid residues of the enzyme that contact with the dye at its binding site on the protein molecule is also the most noncontradictory explanation of the observed (when bound with MDH) decrease in the quantum yield of fluorescence of chlorin e ₆ upon increase in the duration of its quenching. The question of the ability of MDH to act as one of the most sensitive targets responsible for the disturbance of mitochondrial functions and initiation of the apoptosis of tumor cells in the process of photodynamic therapy is discussed.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 749–758, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Bacteriochlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> as a sensitizer for photodynamic therapy

A simple scheme of modification of the native pigment bacteriochlorophyll a, extracted from the biomass of phototropic bacteria, for the purpose of obtaining a water-soluble derivative — bacteriochlorin e ₆ — which is similar in molecular structure to the effective sensitizer chlorin e ₆ and, in addition, has an intense longwave absorption band in the near-infrared region of the spectrum where biological tissues weakly absorb light — has been developed. The ease of production of bacteriochlorin e ₆ in combination with its physicochemical and spectral properties allow it to be considered as a promising sensitizer for photodynamic therapy.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 745–748, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.