Cyclobutane ring opening of allene-enone photoadducts by mercury (II) perchlorate

Cyclobutane ring opening of some allene-enone photoadducts by Hg(ClO₄)₂ in acetone gave diketones which led, in some cases, to bicyclic ketols through intramolecular aldol condensation.     

Efficient VUV xenon excimer laser (λ = 172 nm) AT 6 atm

Experiments on a VUV xenon excimer laser working at medium pressure (3–7 atm) are reported. Xenon gas was excited by an intense electron beam (550 keV, 13 kA, 20 ns) from a 520 Apex machine (S³). Dielectric mirror dammage of intracell cavity and gaz pollution were studied. At 6 atm, we obtained typically 10 MW, 10 ns pulse, with 4 nm spectral width and 1% medium efficiency. This value obtained at 6 atm instead of 12 atm (Hughes) is in agreement with our calculations from kinetics.     

On the limit-classifications of even and odd-order formally symmetric differential expressions

In this paper we consider the formally symmetric differential expressionM [.] of any order (odd or even) ≥ 2. We characterise the dimension of the quotient spaceD(T _max)/D(T _min) associated withM[.] in terms of the behaviour of the determinants det [[f _rg_s](∞)] where 1 ≤n ≤ (order of the expression +1); here [fg](∞) = lim [fg](x), where [fg](x) is the sesquilinear form in f andg associated withM. These results generalise the well-known theorem thatM is in the limit-point case at ∞ if and only if [fg](∞) = 0 for everyf, g ε the maximal domain Δ associated withM.     

Physics perspectives of the ALICE experiment at the large hadron collider

The large hadron collider (LHC) under construction at CERN will deliver ion beams up to centre of mass energies of the order of 5.5 TeV per nucleon, in case of lead. If compared to the available facilities for the study of nucleus-nucleus collisions (SpS and RHIC), this represents a huge step forward in terms of both volume and energy density that can be attained in nuclear interactions. ALICE (a large ion collider experiment) is the only detector specifically designed for the physics of nuclear collisions at LHC, even though it can also study high cross-section processes occurring in proton-proton collisions. The main goal of the experiment is to observe and study the phase transition from hadronic matter to deconfined partonic matter (quark gluon plasma —QGP). ALICE is conceived as a general-purpose detector and will address most of the phenomena related to the QGP formation at LHC energies: for this purpose, a large fraction of the hadrons, leptons and photons produced in each interaction will be measured and identified.     

Pauli equation for a particle in metric and electromagnetic fields

A Pauli theory (Pauli equation and definition of probability current and density) for a particle in weak metric and arbitrary electromagnetic fields is treated. To formulate non-relativistic quantum mechanical problems in arbitrary electromagnetic fields and weak metrics (non-inertial systems, gravitational fields which are distant fields of arbitrary distribution of masses, gravitational waves) it is not necessary to make use of the general-relativistic Dirac equation. Close analogies to the known Pauli theory with electromagnetic fields exist. For different metric fields the corresponding Hamiltonians are given. For quantum systems (H-atoms) which are disturbed by a homogeneous gravitational field and a gravitational wave the resulting shift of energy levels and the transition probability is calculated.     

LIPOSOMAL DELIVERY OF A PHOTOSENSITIZER, BENZOPORPHYRIN DERIVATIVE MONOACID RING A (BPD), TO TUMOR TISSUE IN A MOUSE TUMOR MODEL

Abstract— Biodistribution studies were carried out on ¹⁴C-labeled benzoporphyrin derivative monoacid ring A (BPD), which had been formulated as a unilamellar liposome or taken from a stock solution in dimethyl sulfoxide diluted into phosphate-buffered saline immediately before intravenous injection into DBA/2 mice. By and large the general distribution of BPD to various organs and tissues was comparable for both formulations. It was noted, however, that liposomal material appeared to enter tissues more rapidly and to be cleared more rapidly, as demonstrated by shorter half-lives for a number of tissues including skin, lung and fat, and generally lower levels in most tissues 24 h following administration. Accumulation in tumor tissue was slightly higher with liposomal BPD, and clearance rates for this tissue were equivalent (half-lives 16.1 h for liposomal BPD and 16.9 h for aqueous BPD). When the two preparations were tested in a bioassay in tumor-bearing mice, photodynamic therapy (PDT) with liposomal BPD proved to be superior to the aqueous preparation when PDT was administered 3 h following intravenous administration of BPD. Plasma distribution studies in vitro demonstrated that 91.1 ± 0.3% of the liposomal BPD distributed to the lipoprotein fraction within the first hour of mixing, whereas only 49.1 ± 2.6% of nonliposomal BPD was associated with lipoprotein under the same conditions. Furthermore, while lipoprotein-associated liposomal BPD distributed evenly between all three types of lipoprotein (high, low and very low density), a majority of nonliposomal BPD associated with the high-density lipoprotein fraction.     

Bäcklund Transformations and Solution Hierarchies for the Third Painlevé Equation

In this article our concern is with the third Painlevé equation
d² y /d x ²= (1/ y )(d y /d x )²− (1/ x )(d y /d x ) + ( αy ²+ β )/ x + γy ³+ δ / y
where α, β, γ, and δ are arbitrary constants. It is well known that this equation admits a variety of types of solution and here we classify and characterize many of these. Depending on the values of the parameters the third Painlevé equation can admit solutions that may be either expressed as the ratio of two polynomials in either x or x ^1/3 or related to certain Bessel functions. It is thought that all exact solutions of (1) can be categorized into one or other of these hierarchies. We show how, given a few initial solutions, it is possible to use the underlying structures of these hierarchies to obtain many other solutions. In addition, we show how this knowledge concerning the continuous third Painlevé equation (1) can be adapted and used to derive exact solutions of a suitable discretized counterpart of (1). Both the continuous and discrete solutions we find are of potential importance as it is known that the third Painlevé equation has a large number of physically significant applications.     

Joint mapping of bed elevation and flow depth in microscale morphodynamics experiments

Experiments conducted at very small scales are increasingly being used to study the morphodynamics of sediment beds under the action of flowing water. For such microscale experiments, we propose a measurement approach aimed at jointly mapping the evolving bed topography and distribution of water depth. The proposed measurement system includes a single color camera, a red stripe laser and green fluorescent dye. The stripe laser is scanned back and forth over the experimental surface, while the fluorescent dye is mixed with the flowing water, allowing both the bed topography and water depth to be reconstructed from color images. We present the steps needed for image calibration and processing, including simple models of light refraction and attenuation. The methods are verified using a surface of known geometry, then demonstrated for a challenging groundwater channelization experiment. For this application, co-registered maps of bed topography and water depth are obtained at millimetric resolution for an experimental domain of 650 mm by 650 mm, at a rate of one pair of maps per minute (experimental time). The methods are found to yield accurate results and vividly depict the evolution of a self-formed channel network.     

Methods for the Fourier-series expansion of torsional energies

Several general procedures for the derivation and analysis of a Fourier-series expansion V(?) over computed torsional energies E(?_i) are formulated. STO-3G energy values in n-butane, 1-chloropropane, and 1,2-dichloroethane are used as test data for deriving V(?) with the numerical methods of interpolation and least squares. The accuracy of each derived V(?) is assessed on the basis of calculated conformational properties, mean and rms deviations, and an error curve, V(?)–V(?)_ref, where V(?)_ref represents a reference set of E(?_i). Results indicate that given the same number of expansion terms, interpolation and least squares yield functions of comparable accuracy; however, interpolation is a more efficient procedure for monitoring the accuracy of a function in regions of interest. In cases where there are too few input energies to achieve the desired accuracy, energy derivatives can be employed effectively for expanding the input set. In designing special-purpose functions, the error curve can be used meaningfully as a guide; an example for producing functions that are especially well behaved in regions for gauche conformations is provided. The present study continues to add systematics and rigor to the fitting of an internal rotation potential function from energy data.