INACTIVATION OF Trypanosoma cruzi TRYPOMASTIGOTE FORMS IN BLOOD COMPONENTS BY PHOTODYNAMIC TREATMENT WITH PHTHALOCYANINES

Abstract— -Three phthalocyanine dyes HOSiPcOSi(CH₃)₂(CH₂)₃N(CH₃)₂ (Pc 4), HOSiPc-OSi(CH₃)₂(CH₂)₃N+(CH₃)3I- (Pc 5) and aluminum tetrasulfophthalocyanine hydroxide (AlOHPcS₄) were evaluated for their ability to inactivate the trypomastigote form of Trypanosoma cruzi in fresh frozen plasma (FFP) and red blood cell concentrates (RBCC). The compound Pc 4 was found to be highly effective in killing T. cruzi, Pc 5 less effective and AlOHPcS₄ ineffective. With FFP as the medium, a complete loss of parasite infectivity in vitro (≥5 log₁₀) was found to occur with 2 μ M Pc 4 after irradiation with red light (>600 nm) at a fiuence of 7.5 J/cm², while with RBCC as the medium, a complete loss was found to occur at a fiuence of 15 J/cm². Even without illumination, Pc 4 at 2 μ M also killed about 3.7-4.1 log₁₀ of T. cruzi in FFP during 30 min. Observed differences in T. cruzi killing by the various phthalocyanines may relate to differences in binding; Pc 4 binds to the parasites about twice as much as Pc 5. Ultrastructural analysis of treated parasites suggests that mitochondria are a primary target of this photodynamic treatment. The data indicate that Pc 4 combined with exposure to red light could be used to eliminate bloodborne T. cruzi parasites from blood components intended for transfusion. The inactivation of T. cruzi by Pc 4 in the dark suggests a possible therapeutic application.     

Infrared-vacuum ultraviolet-pulsed field ionization-photoelectron study of CH(3)I(+) using a high-resolution infrared laser

By using a high-resolution single mode infrared-optical parametric oscillator laser to prepare CH(3)I in single (J,K) rotational levels of the nu(1) (symmetric C-H stretching) =1 vibrational state, we have obtained rovibrationally resolved infrared-vacuum ultraviolet-pulsed field ionization-photoelectron (IR-VUV-PFI-PE) spectra of the CH(3)I(+)(X(2)E(32);nu(1)(+)=1;J(+),P(+)) band, where (J,K) and (J(+),P(+)) represent the respective rotational quantum numbers of CH(3)I and CH(3)I(+). The IR-VUV-PFI-PE spectra observed for K=0 and 1 are found to have nearly identical structures. The IR-VUV-PFI-PE spectra for (J,K)=(5,0) and (7, 0) are also consistent with the previous J-selected IR-VUV-PFI-PE measurements. The analysis of these spectra indicates that the photoionization cross section of CH(3)I depends strongly on DeltaJ(+)=J(+)-J: but not on J and K. This observation lends strong support for the major assumption adopted for the semiempirical simulation scheme, which has been used for the simulation of the origin bands observed in VUV-PFI-PE study of polyatomic molecules. Using the state-to-state photoionization cross sections determined in this IR-VUV study, we have obtained excellent simulation of the VUV-PFI-PE origin band of CH(3)I(+)(X (2)E(32)), yielding more precise IE(CH(3)I)=76 930.7+/-0.5 cm(-1) and nu(1) (+)=2937.8+/-0.2 cm(-1).     

Polymer matrix dependence of conformational dynamics within a π-stacked perylenediimide dimer and trimer revealed by single molecule fluorescence spectroscopy

The conformation of embedded molecule in a polymer matrix is sensitive to the local nano-environment that the molecule experiences. Particularly, single molecule spectroscopic methods have been utilized to visualize each molecular conformation in local sites of the polymer matrix by monitoring rotational diffusion and fluctuating fluorescence of the molecule. Here, we have performed single molecule spectroscopic experiments on a π-stacked perylenediimide (PDI) dimer and trimer, in which enhanced π-π interaction in π-stacked PDIs makes the fluorescence lifetime longer, embedded in two different polymers, namely poly(methyl methacrylate) (PMMA) and poly(butyl methacrylate) (PBMA), to reveal the conformational change depending on the polymer matrix. The fluorescence lifetimes of π-stacked PDIs are influenced by polymer surroundings because their molecular conformations are dependent on their interactions with the local environment in the polymer matrix. Furthermore, from an in-depth analysis of autocorrelation functions of fluorescence intensity trajectories, we could assign that the first autocorrelation value (lag 1) is larger as the intensity trace becomes more fluctuating. Thus, we expect that π-stacked PDIs, a model system for the formation of PDI excimer-like states, can be utilized to probe the surrounding nano-environment by monitoring the conformational change in real time.     

A combined VUV synchrotron pulsed field ionization-photoelectron and IR-VUV laser photoion depletion study of ammonia

The synchrotron based vacuum ultraviolet-pulsed field ionization-photoelectron (VUV-PFI-PE) spectrum of ammonia (NH(3)) has been measured in the energy range 10.12-12.12 eV using a room-temperature NH(3) sample. In addition to extending the VUV-PFI-PE measurement to include the v(2)(+) = 0, 10, 11, 12, and 13 and the v(1)(+) + nv(2)(+) (n = 4-9) vibrational bands, the present study also reveals photoionization transition line strengths for higher rotational levels of NH(3), which were not examined in previous PFI-PE studies. Here, v(1)(+) and v(2)(+) represent the N-H symmetric stretching and inversion vibrational modes of the ammonia cation (NH(3)(+)), respectively. The relative PFI-PE band intensities for NH(3)(+)(v(2)(+)=0-13) are found to be in general agreement with the calculated Franck-Condon factors. However, rotational simulation indicates that rotational photoionization transitions of the P-branches, particularly those for the lower v(2)(+) PFI-PE bands, are strongly enhanced by forced rotational autoionization. For the synchrotron based VUV-PFI-PE spectrum of the origin band of NH(3)(+), rotational transition intensities of the P-branch are overwhelming compared to those of other rotational branches. Similar to that observed for the nv(2)(+) (n = 0-13) levels, the v(1)(+) + nv(2)(+) (n = 4-9) levels are found to have a positive anharmonicity constant; i.e., the vibrational spacing increases as n is increased. The VUV laser PFI-PE measurement of the origin band has also been made using a supersonically cooled NH(3) sample. The analysis of this band has allowed the direct determination of the ionization energy of NH(3) as 82158.2 +/- 1.0 cm(-1), which is in good accord with the previous PFI-PE and photoionization efficiency measurements. Using the known nd(v(2)(+)=1,1(0)<--0(0)) Rydberg series of NH(3) as an example, we have demonstrated a valuable method based on two-color infrared-VUV-photoion depletion measurements for determining the rotational character of autoionizing Rydberg states.     

Design study of a radio-frequency quadrupole for high-intensity beams

The Rare isotope Accelerator Of Newness(RAON) heavy-ion accelerator has been designed for the Rare Isotope Science Project(RISP) in Korea. The RAON will produce heavy-ion beams from 660-MeV-proton to200-MeV/u-uranium with continuous wave(CW) power of 400 k W to support research in various scientific fields.Its system consists of an ECR ion source, LEBTs with 10 ke V/u, CW RFQ accelerator with 81.25 MHz and 500 ke V/u, a MEBT system, and a SC linac. In detail, the driver linac system consists of a Quarter Wave Resonator(QWR) section with 81.25 MHz and a Half Wave Resonator(HWR) section with 162.5 MHz, Linac-1, and a Spoke Cavity section with 325 MHz, Linac-2. These linacs have been designed to optimize the beam parameters to meet the required design goals. At the same time, a light-heavy ion accelerator with high-intensity beam, such as proton,deuteron, and helium beams, is required for experiments. In this paper, we present the design study of the high intensity RFQ for a deuteron beam with energies from 30 ke V/u to 1.5 MeV/u and currents in the m A range. This system is composed of an Penning Ionization Gauge ion source, short LEBT with a RF deflector, and shared SC Linac. In order to increase acceleration efficiency in a short length with low cost, the 2nd harmonic of 162.5 MHz is applied as the operation frequency in the D~+RFQ design. The D~+RFQ is designed with 4.97 m, 1.52 bravery factor. Since it operates with 2nd harmonic frequency, the beam should be 50% of the duty factor while the cavity should be operated in CW mode, to protect the downstream linac system. We focus on avoiding emittance growth by the space-charge effect and optimizing the RFQ to achieve a high transmission and low emittance growth. Both the RFQ beam dynamics study and RFQ cavity design study for two and three dimensions will be discussed.     

Rovibrationally selected and resolved state-to-state photoionization of ethylene using the infrared-vacuum ultraviolet pulsed field ionization-photoelectron method

By preparing ethylene [C2H4(X1Ag)] in selected rotational levels of the nu11(b1u), nu2+nu12(b1u), or nu9(b2u) vibrational state with infrared (IR) laser photoexcitation prior to vacuum ultraviolet (VUV) laser photoionization, we have recorded rotationally resolved pulsed field ionization-photoelectron (PFI-PE) spectra for C2H4+(X2B3u) in the energy region of 0-3000 cm(-1) above the ionization energy (IE) of C2H4(X1Ag). Here, nu2(ag), nu9(b2u), nu11(b1u), and nu12(b1u) represent the C-C stretching, CH2 stretching, CH2 stretching, and CH2 bending modes of C2H4(X1Ag), respectively. The fully rovibrationally resolved spectra have allowed unambiguous symmetry assignments of the observed vibrational bands, which in turn have provided valuable information on the photoionization dynamics of C2H4. The IR-VUV photoionization of C2H4(X1Ag) via the nu11(b1u) or nu2+nu12(b1u) vibrational states is found to predominantly produce vibrational states of C2H4+(X2B3u) with b1u symmetry, which cannot be observed in single-photon VUV-PFI-PE measurements of C2H4(X1Ag). The analysis of the observed IR-VUV-PFI-PE bands has provided the IE(C2H4) = 84,790.2(2) cm(-1) and accurate vibrational frequencies for the nu4+(au)[84.1(2) cm(-1)], nu12+(b1u)[1411.7(2) cm(-1)], nu4+ +nu12+(b1g)[1482.5(2) cm(-1)], nu2+(ag)[1488.3(2) cm(-1)], nu2+ + nu4+(au)[1559.2(2) cm(-1)], 2nu4+ + nu12 +(b1u)[1848.5(2) cm(-1)], 4nu4+ + nu12 +(b1u)[2558.8(2) cm(-1)], nu2+ + nu12 +(b1u)[2872.7(2) cm(-1)], and nu11+(b1u)[2978.7(2) cm(-1)] vibrational states of C2H4+(X2B3u), where nu4+ is the ion torsional state. The IE(C2H4) and the nu4+(au), nu2+(ag), and nu2+ + nu4+ (au) frequencies are in excellent accord with those obtained in previous single-photon VUV-PFI-PE measurements. The other ion vibrational frequencies represent new experimental determinations. We have also performed high-level ab initio anharmonic vibrational frequency calculations for C2H4(X1Ag) and C2H4+(X2B3u) at the CCSD(T)/aug-cc-pVQZ level for guidance in the assignment of the IR-VUV-PFI-PE spectra. All theoretical vibrational frequencies for the neutral and ion, except the ion torsional frequency, are found to agree with experimental vibrational frequencies to better than 1%.     

Spontaneous self-organization enables dielectrophoresis of small nanoparticles and formation of photoconductive microbridges

Detailed understanding of the mechanism of dielectrophoresis (DEP) and the drastic improvement of its efficiency for small size-quantized nanoparticles (NPs) open the door for the convergence of microscale and nanoscale technologies. It is hindered, however, by the severe reduction of DEP force in particles with volumes below a few hundred cubic nanometers. We report here DEP assembly of size-quantized CdTe nanoparticles (NPs) with a diameter of 4.2 nm under AC voltage of 4-10 V. Calculations of the nominal DEP force for these NPs indicate that it is several orders of magnitude smaller than the force of the Brownian motion destroying the assemblies even for the maximum applied AC voltage. Despite this, very efficient formation of NP bridges between electrodes separated by a gap of 2 μm was observed even for AC voltages of 6 V and highly diluted NP dispersions. The resolution of this conundrum was found in the intrinsic ability of CdTe NPs to self-assemble. The species being assembled by DEP are substantially bigger than the individual NPs. DEP assembly should be treated as a process taking place for NP chains with a length of ~140 nm. The self-assembled chains increase the nominal volume where the polarization of the particles takes place, while retaining the size-quantized nature of the material. The produced NP bridges were found to be photoactive, producing photocurrent upon illumination. DEP bridges of quantum confined NPs can be used in fast parallel manufacturing of novel MEMS components, sensors, and optical and optoelectronic devices. Purposeful engineering of self-assembling properties of NPs makes possible further facilitation of the DEP and increase of complexity of the produced nano- and microscale structures.     

Facile fabrication of 2-dimensional arrays of sub-10 nm single crystalline Si nanopillars using nanoparticle masks

A simple procedure for the fabrication of sub-10 nm scale Si nanopillars in a 2-D array using reactive ion etching with 8 nm Co nanoparticles as etch masks is demonstrated. The obtained Si nanopillars are single crystalline tapered pillar structures of 5 nm (top) x 8 nm (bottom) with a density of approximately 4 x 10(10) pillars cm(-2) on the substrate, similar to the density of Co nanoparticles distributed before the ion etching process. The uniform spatial distribution of the Si nanopillars can also be patterned into desired positions. Our fabrication method is straightforward and requires mild process conditions, which can be extended to patterned 2-D arrays of various Si nanostructures.     

A two-color infrared-vacuum ultraviolet laser pulsed field ionization photoelectron study of NH3

We have observed fully rotationally resolved transitions of the photoelectron vibrational bands 2(4), 2(5), 1(1)2(1), and 1(1)2(3) for ammonia cation (NH3+) by two-color infrared (IR)-vacuum ultraviolet (VUV)- pulsed field-ionization photoelectron (PFI-PE) measurements. By preparing an intermediate rovibrational state of neutral NH(3) with a known parity by IR excitation followed by VUV-PFI-PE measurements, we show that the photoelectron parity can be determined unambiguously. The IR-VUV-PFI-PE measurement of the 2(4) band clearly reveals the formation of both even and odd l states for the photoelectrons, where l is the orbital angular momentum quantum number. This observation is consistent with the conclusion that the lack of inversion symmetry for NH3 and NH3+ allows odd/even l mixings, rendering the production of both odd and even l states for the photoelectrons. Evidence is also found, indicating that the photoionization transitions with DeltaK=0 are strongly favored compared to that with DeltaK=3. For the 2(5), 1(1)2(1), and 1(1)2(3) bands, only DeltaK=0 transitions for the production of even l photoelectron states from the J'K'=2(0) rotational level of NH3(nu1=1) are observed. The preferential formation of even l photoelectron states for these vibrational bands is attributed to the fact that the DeltaK=0 transitions for the formation of odd l photoelectron states from the 2(0) rotational level of NH3(nu1=1) are suppressed by the constraint of nuclear-spin statistics. In addition to information obtained on the photoionization dynamics of NH3, this experiment also provides a more precise value of 3232+/-10 cm-1 for the nu1+ (N-H stretch) vibrational frequency of NH3+.     

Determination of the rate constant for the OH(X2Pi) + OH(X()Pi) --> O(3P) + H2O reaction over the temperature range 293-373 K

The rate constant for the reaction OH(X2Pi) + OH(X2Pi) --> O(3P) + H2O has been measured over the temperature range 293-373 K and pressure range 2.6-7.8 Torr in both Ne and Ar bath gases. The OH radical was created by 193 nm laser photolysis of N2O to produce O(1D) atoms that reacted rapidly with H2O to produce the OH radical. The OH radical was detected by quantitative time-resolved near-infrared absorption spectroscopy using Lambda-doublet resolved rotational transitions of the first overtone of OH(2,0) near 1.47 microm. The temporal concentration profiles of OH were simulated using a kinetic model, and rate constants were determined by minimizing the sum of the squares of residuals between the experimental profiles and the model calculations. At 293 K the rate constant for the title reaction was found to be (2.7 +/- 0.9) x 10(-12) cm(3) molecule(-1) s(-1), where the uncertainty includes an estimate of both random and systematic errors at the 95% confidence level. The rate constant was measured at 347 and 373 K and found to decrease with increasing temperature.