Distribution of Chlorophyll- and Bacteriochlorophyll-derived Photosensitizers in Human Blood Plasma

Chlorophyll a and, in particular, bacteriochlorophyll a derivatives are promising candidates for photosensitizers in photodynamic therapy. The distribution of 21 (bacterio)chlorophyll derivatives among human blood plasma fractions was studied by iodixanol gradient ultracentrifugation and in situ absorption spectroscopy. Modifications of the natural pigments involved the central metal (Mg²⁺, Zn²⁺, Pd²⁺, none), the isocyclic ring (closed, open and taurinated), substituents at C-3 (vinyl, acetyl, 1-hydroxyethyl) and C-17³ (phytyl ester, free acid). Cellular blood components bound only a small fraction of the pigments. Distribution among low-density lipoproteins (LDL), high-density lipoproteins (HDL) and high-density proteins (HDP) of the plasma was influenced as follows: (1) application in Cremophor^® EL slightly altered pigment distribution by lipoprotein modification, (2) only very polar pigments with multiple hydrophilic substituents showed substantial HDP binding, (3) the presence of the esterifying alcohol at C-17³ caused enrichment in LDL, this was more pronounced with bacteriochlorophylls than with chlorophylls, (4) substituents at C-3 had only little influence on the distribution, (5) Zn²⁺-complexes were enriched in HDL compared to Mg²⁺ and Pd²⁺ complexes, indicating specific binding of the former. Equilibration of pigments among the different fractions was largely complete within 3 h.     

On the chemical synthesis of titanium nanoparticles from ionic liquids

Abstract  

We report on attempts towards the synthesis of titanium nanoparticles using a wet chemical approach in imidazolium-based ionic liquids (ILs) under reducing conditions. Transmission electron microscopy finds nanoparticles in all cases. UV/Vis spectroscopy confirms the nanoparticulate nature of the precipitate, as in all cases an absorption band between ca. 280 and 300 nm is visible. IR spectroscopy shows that even after extensive washing and drying, some IL remains adsorbed on the nanoparticles. Raman spectroscopy suggests the formation of anatase nanoparticles, but X-ray diffraction reveals that, possibly, amorphous titania forms or that the nanoparticles are so small that a clear structure assignment is not possible. The report thus shows that (possibly amorphous) titanium oxides even form under reducing conditions and that the chemical synthesis of titanium nanoparticles in ILs remains elusive.     

Real-time increase in depth of field of an uncooled thermal camera using several phase-mask technologies

Imaging systems that combine a phase mask in the pupil and digital postprocessing may have better performance than conventional ones. We have built such a system to enhance the depth of field of an uncooled thermal camera. The phase masks are binary, their structures are optimized thanks to an image quality criterion, and they have been realized with three different technologies that give equivalent results. The deconvolution postprocessing is performed in real time with a graphics processing unit. A significant increase of the depth of field of a factor 3 has been obtained.     

Generation of 520 mW pulsed blue light by frequency doubling of an all-fiberized 978 nm Yb-doped fiber laser source

Pulsed blue light at 489 nm has been generated by second-harmonic-generation of a nanosecond pulsed master-oscillator power amplifier system based on a short Yb(3+) doped single-mode fiber amplifier at 978 nm and an external-cavity diode laser as seed source. The Yb(3+)-doped fiber was core-pumped by a W type Nd(3+) doped double-clad fiber laser operating on the transition near 930 nm ((4)F(3/2)→(4)I(9/2)). 520 mW of average power was generated at 489 nm using a periodically poled MgO:LiNbO(3), corresponding to a conversion efficiency of 34%.     

A sliced inverse regression approach for data stream

In this article, we focus on data arriving sequentially by blocks in a stream. A semiparametric regression model involving a common effective dimension reduction (EDR) direction \(\beta \) is assumed in each block. Our goal is to estimate this direction at each arrival of a new block. A simple direct approach consists of pooling all the observed blocks and estimating the EDR direction by the sliced inverse regression (SIR) method. But in practice, some disadvantages appear such as the storage of the blocks and the running time for large sample sizes. To overcome these drawbacks, we propose an adaptive SIR estimator of \(\beta \) based on the optimization of a quality measure. The corresponding approach is faster both in terms of computational complexity and running time, and provides data storage benefits. The consistency of our estimator is established and its asymptotic distribution is given. An extension to multiple indices model is proposed. A graphical tool is also provided in order to detect changes in the underlying model, i.e., drift in the EDR direction or aberrant blocks in the data stream. A simulation study illustrates the numerical behavior of our estimator. Finally, an application to real data concerning the estimation of physical properties of the Mars surface is presented.     

Frontier estimation with local polynomials and high power-transformed data

We present a new method for estimating the frontier of a sample. The estimator is based on a local polynomial regression on the power-transformed data. We assume that the exponent of the transformation goes to infinity while the bandwidth goes to zero. We give conditions on these two parameters for obtaining almost complete convergence. The asymptotic conditional bias and variance of the estimator are provided and its good performance is illustrated for some finite sample situations.     

Photochemistry of Bacteriochlorophylls in Human Blood Plasma: 1. Pigment Stability and Light-induced Modifications of Lipoproteins

Transmetalated derivatives of bacteriochlorophyll are promising sensitizers in photodynamic therapy. Protocols using short delay times between injection and irradiation cause interest in the photochemistry of these pigments in the blood. Using near-infrared irradiation where these pigments absorb strongly, we have studied the photochemistry of Zn- and Pd-bacteriopheophorbide (WST09), and of the highly polar taurinated Pd-derivative, WST11, in isolated fractions of human blood plasma. The stability of all pigments is increased in blood plasma, compared with monomeric solutions. Pd-bacteriopheophorbide is much more stable than the other two derivatives. It also has a higher capacity for inducing reactive oxygen species, yet the consumption of oxygen is comparable. There is furthermore evidence for photobleaching under anoxic conditions. The generation of hydroperoxides (ROOH) is faster with Pd- than with Zn-complexes; the formation of endoperoxides (ROOR′), measured as thiobarbituric acid reactive substances, is comparable with the two central metals. Formation of both ROOH and ROOR′ is increased in low-density lipoproteins (LDL) compared with high-density lipoproteins (HDL), which is probably related to the higher concentration of target molecules in the former. In HDL, extensive cross-linking is induced among the apolipoproteins; judged from the electrophoretic mobility of LDL and HDL particles, there is also a gross structural change. Photosensitized cross-linking is much less pronounced with high-density proteins.     

An analytical approach to global optimization

Global optimization problems with a few variables and constraints arise in numerous applications but are seldom solved exactly. Most often only a local optimum is found, or if a global optimum is detected no proof is provided that it is one. We study here the extent to which such global optimization problems can be solved exactly using analytical methods. To this effect, we propose a series of tests, similar to those of combinatorial optimization, organized in a branch-and-bound framework. The first complete solution of two difficult test problems illustrates the efficiency of the resulting algorithm. Computational experience with the programbagop, which uses the computer algebra systemmacsyma, is reported on. Many test problems from the compendiums of Hock and Schittkowski and others sources have been solved.The research of the first and the third authors has been supported by AFOSR grants #0271 and #0066 to Rutgers University. Research of the second author has been supported by NSERC grant #GP0036426 and FCAR grants #89EQ4144 and #90NC0305.     

Synthesis of new amphiphilic and lypophilic polymer networks containing 2‐methyl‐ and 2‐nonyl‐2‐oxazoline by the macroinitiator method

New amphiphilic and lypophilic polymer networks were obtained by the copolymerization of 2‐methyl‐2‐oxazoline (MeOXA), and/or 2‐nonyl‐2‐oxazoline (NoOXA) and 2,2′‐tetramethylenebis(2‐oxazoline) (BisOXA), respectively, initiating the copolymerization by random copolymers of chloromethylstyrene and methyl methacrylate or of chloromethylstyrene and styrene (macroinitiator method). Potassium iodide was used as an activator agent and the reaction was carried out in benzonitrile at 110 °C. In general, the polymer gels were obtained with a yield of 62 to 88%. The networks were characterized by high‐resolution magic angle spinning (HRMAS) NMR spectroscopy and by its absorption of polar and nonpolar solvents. In the case of amphiphilic polymer networks, the absorption of solvents depends on the molar ratio of 2‐methyl‐ to 2‐nonyl‐2‐oxazoline inside the polymer network favoring the absorption of polar solvents with a higher content of 2‐methyl‐2‐oxazoline. These gels showed a maximal swelling degree of 13 mL of water, 20 mL of methanol, and 13 mL of chloroform, respectively, per g of polymer. The lypophilic polymer networks containing only 2‐nonyl‐2‐oxazoline showed a maximal swelling degree of 8 mL of toluene, 14 mL of chloroform, and 2 mL of methanol, respectively, per g of the lypophilic network. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 122–128, 2005