The 1-bromoheptane photodissociation near 234 nm

The photodissociation of n-C₇H₁₅Br, near the red wing of the absorption A-band, has been investigated utilizing the velocity mapped ion imaging technique. Both the speed and angular distributions of Br^*(²P_1/2) and Br(²P_3/2) fragments were determined. The experimental data indicate that the photodissociation in the investigated range originates from adiabatic and non-adiabatic transitions of the three low-lying dissociative electronic states. The fragments kinetic energies and the angular distributions show that about 70% energy is deposited into the internal energy of the fragments. These results can be explained using soft impulsive model. The experiment also shows that the anisotropy parameter for Br^* is sensitive to the photolysis wavelength.     

Comparison of 1064 nm and 266 nm excitation of laser-induced plasmas for several types of plastics and one explosive

Comparative measurements of Laser-Induced Breakdown Spectroscopy (LIBS) for ultraviolet (UV) and near infrared (NIR) excitation wavelengths on a wide range of plastics and one kind of explosive are presented. The focus of work is on the influence of laser wavelength on the Signal-to-peak to peak noise ratio (SPPNR) for selected emission lines as well as the plasma thresholds for NIR and UV excitation wavelengths. The merits of both excitation wavelengths are discussed with respect to the detection of explosives.     

Multilayer core-shell nanostructures for enhanced 808 nm responsive upconversion

The construction of core-shell structure is an effective strategy for promoting the emission efficiency of upconversion nanocrystals(UCNCs). In this work, the UCNCs based on Nd-doping with a multilayer coreshell nanostructure are fabricated toward achieving efficient upconversion for 808 nm excitation, which have great potential for optical applications, especially photobiological applications.     

Hydrogen Production via Synthetic Biogas Reforming in Atmospheric-Pressure Microwave (915 MHz) Plasma at High Gas-Flow Output

Plasma Chemistry and Plasma Processing - This paper is a contribution to the development of microwave plasma-based technology for hydrogen (H2) production from a so-called synthetic biogas,...     

Maintenance of Plasma Layer in Intersected Microwave Beams in the Range of Frequency from 10 to 60 GHz: Analysis and Simulation

Plasma Chemistry and Plasma Processing - The paper presents the results of theoretical analysis and numerical modeling of physical processes occurring in microwave discharge supported in two...     

Large-area and high-density gold nanoparticle arrays with sub-10 nm gaps

Electrochemical techniques are widely used for the fabrication of nanostructured materials, yet a desired high-density nanoparticle arrays remains a challenge. Here large-area and high-density gold nanoparticle arrays with sub-10 nm gaps have been, for the first time, synthesized on Si(1 0 0) substrate within an electrochemical deposition system via the application of an unusually high over-potential. The extremely high over-potential contributes to the relatively small critical island size and high nucleation rate. It is believed that this method can be extended to the electrochemical fabrication nanoparticle arrays of other materials.     

Monitoring nanobubble nucleation at early-stage within a sub-9 nm solid-state nanopore

Nanobubble nucleation study is important for understanding the dynamic behavior of nanobubble growth, which is instructive for the nanobubble applications. Benefiting from nanopore fabrication, herein, we fabricated a sub-9 nm SiN_X nanopore with the comparable size to nanobubbles at early-stage. The confined nanopore interface serves as a generator for producing nanobubbles by the chemical reaction between NaBH₄ and H₂O and as an ultra-sensitive sensor for monitoring the H₂ nanobubble nucleation process. By carrying out the NaBH₄ concentration-dependent experiments, we found the life-time of nanobubbles decreased 250 times and the frequency of nanobubble generation increased 38 times with the NaBH₄ concentration increasing from 6 to 100 mM. The long-time equilibrium between gas molecules inward flux and outward flux could prolong the life-time of nanobubbles to hundreds of milliseconds at low NaBH₄ concentration. The raw current trace depicted that the transient accumulation and dissolution of cavity occurred during all the life-time of nanobubbles. Therefore, the sub-9 nm SiN_X nanopore shows a strong ability for real-time monitoring the nanobubble nucleation at early-stage with high temporal and spatial resolution. This work provides a guide to study the dynamic and stochastic characteristics of nanobubbles.     

Electropolymerizing polyaniline on undoped 100 nm diamond powder and its electrochemical characteristics

Conductive polyaniline (PANI) was electropolymerized on undoped 100 nm diamond powders in sulphuric acid solution containing aniline to improve the conductivity and the electrochemistry of the nano- or submicro-scaled diamond particles. Cyclic voltammetry (CV) experiment was carried out at an upper potential of 1.1 V in initial sweeps and a potential range of ?0.2–0.9 V for the growth of PANI on a diamond powder electrode. Field emission-scanning electron microscope (FESEM) result reveals that the diamond particles were well coated by PANI films with globular or fibroid surface morphology. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were employed to investigate the electrochemical properties of the PANI/diamond composite electrode. It presents lower resistance and better capacitance than the pristine diamond powder.     

Detection of OH on photolysis of styrene oxide at 193 nm in gas phase

Photodissociation of styrene oxide at 193 nm in gas phase generates OH, as detected by laser-induced fluorescence technique. Under similar conditions, OH was not observed from ethylene and propylene oxides, primarily because of their low absorption cross-sections at 193 nm. Mechanism of OH formation involves first opening of the three-membered ring from the ground electronic state via cleavage of either of two CO bonds, followed by isomerization to enolic forms of phenylacetaldehyde and acetophenone, and finally scission of the COH bond of enols. Ab initio molecular orbital calculations support the proposed mechanism.     

Foreign gas broadening and shift of the strongly “forbidden” lead line at 1278.9 nm

The collisional broadening and shift rate coefficients of the “forbidden“ 6p^{2 3}P₀ → 6p^{2 3}P₁ transition in lead were determined by diode laser absorption measurements performed simultaneously in two resistively heated hot-pipes. One hot-pipe contained Pb vapor and noble gas (Ar or He) at low pressure, while the other was filled with Pb and noble gas at variable pressure. The measurements were performed at temperatures of 1220 K and 1290 K, i.e., lead number densities of 4.8 × 10¹⁵ cm^− 3 and 1.2 × 10¹⁶ cm^− 3. The broadening rates were obtained by fitting the experimental collisionally broadened absorption line shapes to theoretical Voigt profiles. The shift rates were determined by measuring the difference between the peak absorption positions in the spectra measured simultaneously in the heat pipe filled with noble gas at reference pressure and the one with noble gas at variable pressure. The following data for the broadening and shift rate coefficients due to collisions with Ar and He were obtained: γ_B^Ar = (3.4 ± 0.1) × 10^− 10 cm³ s^− 1, γ_B^He = (3.8 ± 0.1) × 10^− 10 cm³ s^− 1, γ_S^Ar = (− 7.3 ± 0.8) × 10^− 11 cm³ s^− 1, γ_S^He = (− 6.5 ± 0.7) × 10^− 11 cm³ s^− 1.     

The photodissociation of SO2 between 200 and 197 nm

Pump-probe experiments on the C state of SO₂ have been performed to assess the details of the oxygen photodissociation process between 197 and 200 nm. The findings show that a prompt dissociation event occurs in less than 265, but more than 100 fs. The reorganization of internal energy occurs in 15 or 28 ps depending upon the excitation energy; the change in lifetime represents contributions from asymmetric vibrational states seen in previous experiments. In addition, a long-lived species (lifetime >150 ps) exists that does not decay on the timeframe of our experiment. These findings are discussed in comparison to previous studies, particularly in the context of an avoided crossing in this region of the potential energy surface of SO₂.     

Bacterial Inactivation by Solar Ultraviolet Radiation Compared with Sensitivity to 254 nm Radiation

Our goal was to derive a quantitative factor that would allow us to predict the solar sensitivity of vegetative bacterial cells to natural solar radiation from the wealth of data collected for cells exposed to UVC (254 nm) radiation. We constructed a solar effectiveness spectrum for inactivation of vegetative bacterial cells by combining the available action spectra for vegetative cell killing in the solar range with the natural sunlight spectrum that reaches the ground. We then analyzed previous studies reporting the effects of solar radiation on vegetative bacterial cells and on bacterial spores. Although UVC-sensitive cells were also more sensitive to solar radiation, we found no absolute numerical correlation between the relative solar sensitivity of vegetative cells and their sensitivity to 254 nm radiation. The sensitivity of bacterial spores to solar exposure during both summer and winter correlated closely to their UVC sensitivity. The estimates presented here should make it possible to reasonably predict the time it would take for natural solar UV to kill bacterial spores or with a lesser degree of accuracy, vegetative bacterial cells after dispersion from an infected host or after an accidental or intentional release.     

Tomographic quantitative phase measurement by hard X-ray micro-interferometer with 250 nm spatial resolution

Tomographic quantitative phase measurement has been carried out by using a hard X-ray micro-interferometer in Hyogo-ID at SPring-8. The micro-interferometer combines an imaging microscope and a wavefront-division-type interferometer by using a novel optical element called a “twin zone plate.” A three-dimensional quantitative phase distribution of a glass capillary with an outer diameter of 6 μm was successfully obtained with the tomographic technique. The measured refractive index corresponded to the ideal value. The spatial resolution of the tomographic image was estimated to be 250 nm and the density resolution was estimated to be 0.6 g/cm³.     

The three-body dissociation dynamics of Cl2O at 248 and 193 nm

The photodissociation of Cl₂O has been studied at 248 and 193 nm using photofragment translational spectroscopy (PTS) experiments with tunable VUV photoionization detection. The sole products observed were Cl, O and ClO fragments. Based on the derived translational energy distributions for the ClO and Cl photofragments we conclude that at 248 nm 15% of Cl₂O excitation results in three-body dissociation. At 193 nm no Cl₂ fragments are observed and we conclude that the oxygen atoms arise solely from three-body dissociation. Dissociation geometries derived from forward convolution fitting suggest two qualitatively distinct three-body dissociation pathways: asymmetric concerted dissociation and symmetric concerted dissociation in agreement with recent theoretical predictions.     

Study on continuous (254 nm) and pulsed UV (266 and 355 nm) lights on BVD virus inactivation and its effects on biological properties of fetal bovine serum

Both continuous UV lights and pulsed UV lasers have potentials to inactivate known and emerging viruses. Bovine viral diarrhea virus (BVDV), from the Pestivirus genus, is known to be a common viral contamination in (fetal) bovine serum (FBS). Also, BVDV has been used in the blood product industry as a surrogate for Hepatitis C virus (HCV), due to its similarity in structure and genome. Germicidal UV lamp with the wavelength of 254 nm and Nd:YAG laser (pulsed UV laser) in its third and fourth harmonic with the wavelengths of 355 and 266 nm, respectively, were used. BVDV suspended in PBS or FBS were exposed to different intensities and doses and then reduction in BVDV titer were calculated. To complete inactivation of BVDV suspended in PBS and PBS containing 5% FBS, 1.6 (t = 30 min) and 3.2 (t = 60 min) J/cm² were used. The minimum doses for inactivation of BVDV suspended in PBS with the 355 and 266 nm of pulsed UV laser were 352 and 92.25 J/cm². Also, the minimum doses for inactivation of BVDV suspended in FBS with 355 and 266 nm wavelengths of pulsed UV laser were 704 and 127 J/cm². To evaluate the irradiated FBS quality to support cell culture growth, FBS was treated with the dose of 190.5 J/cm² and 266 nm pulsed UV laser and was used to grow Vero cells, in comparison with a control group. The viability of cells in two groups was identical and the statistical evaluation showed no significant difference in 12 passages.     

Thermodynamic evaluation and optimization of the (NaCl + KCl + MgCl2 + CaCl2 + MnCl2 + FeCl2 + CoCl2 + NiCl2) system

A complete critical evaluation of all available phase diagram and thermodynamic data has been performed for all condensed phases of the (NaCl + KCl + MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) system, and optimized model parameters have been found. The (MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) subsystem has been critically evaluated in a previous article. The model parameters obtained for the binary subsystems can be used to predict thermodynamic properties and phase equilibria for the multicomponent system. The Modified Quasichemical Model was used for the molten salt phase, and the (MgCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) solid solution was modeled using a cationic substitutional model with an ideal entropy and an excess Gibbs free energy expressed as a polynomial in the component mole fractions. Finally, the (Na,K)(Mg,Ca,Mn,Fe,Co,Ni)Cl₃ and the (Na,K)₂(Mg,Mn,Fe,Co,Ni)Cl₄ solid solutions were modeled using the Compound Energy Formalism.     

Rationally designed meso-benzimidazole-pyronin with emission wavelength beyond 700 nm enabling in vivo visualization of acute-liver-injury-induced peroxynitrite

Fluorescent dyes with fluorescence emission above 700 nm are favorable for bio-imaging due to the higher tissue transparency and lower background fluorescence. In this study, we present a meso-benzimidazole-pyronin platform (SiBMs) with fluorescence emission maxima above 700 nm, which possess good cell permeability, photostability, and lysosomal localization. The great photophysical properties of the SiBMs encouraged us to further exploit their application toward bio-imaging. We synthesized the reduced ‘dihydro’ derivative HSiBM3 for sensing ONOO^?, with high selectivity and sensitivity and a fast fluorescence “off-on” response (within 2 s). Then, we confirmed the potential of HSiBM3 for visualizing exogenous and endogenous ONOO^? in cells and mice. More importantly, HSiBM3 was successfully employed for visualizing acute-liver-injury-induced peroxynitrite.     

Synthesis and characterization of sulphonated core-shell latices in the size range between 30 and 80 nm

The objective of the current work was the synthesis of sulphonated core-shell nanolatices and to investigate to which extend it is possible to control the final surface charge of such latices. For this purpose differently sized polystyrene seed latices with average diameters in the size range between 30 and 80 nm were synthesized by emulsion polymerization. To obtain the final latices, a sulphonated comonomer was incorporated in the outer surface shell of the particles by further reaction of the seed latices with styrene and sodium styrene sulphonate (NaSS). In a first test series the seed latex surface was modified with four different amounts of NaSS. In a second test series four different seed latices were reacted with the same amount of NaSS. In the last set of reactions the seed latices were reacted with different amounts of NaSS and in these reactions the ratio of added NaSS to the specific surface area of the seed latex was kept constant to obtain differently sized latices of the same surface charge density. The yield of sulphonic acid groups in the particle shell was found between 57 and 74% after an intensive cleaning step by ion exchange. The results show possibilities for a reproducible synthesis of small sulphonated latex particles with a desired surface charge density.     

Thermodynamic evaluation and optimization of the (MgCl2 + CaCl2 + MnCl2 + FeCl2 + CoCl2 + NiCl2) system

A complete critical evaluation of all available phase diagram and thermodynamic data has been performed for all condensed phases of the (MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) system, and optimized model parameters have been found. The model parameters obtained for the binary subsystems can be used to predict thermodynamic properties and phase equilibria for the multicomponent system. The Modified Quasichemical Model was used for the molten salt phase, and the (MgCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) solid solution was modeled using a cationic substitutional model with an ideal entropy and an excess Gibbs free energy expressed as a polynomial in the component mole fractions. This is the first of two articles on the optimization of the (NaCl + KCl + MgCl₂ + CaCl₂ + MnCl₂ + FeCl₂ + CoCl₂ + NiCl₂) system.     

What Caused the Formation of the Absorption Maximum at 421 nm in vivo Spectra of Rhodopseudomonas palustris

A spectral peak at ~421 nm appeared in vivo spectrum of Rhodopseudomonas palustris CQV97 cultured in acetate–glutamate medium (M1) but not in acetate–ammonium sulfate medium (M2). However, the spectral origin of 421 nm peak was not clear and frequently attributed to carotenoid component(s). In this study, comparative analysis of the extracted components showed that magnesium protoporphyrin IX monomethylester (MPE) was accumulated as one of the predominate components in M1 culture. The amounts of bacteriochlorophyll a in M1 culture were higher than that in M2, whereas the amounts of carotenoids were nearly identical in both cultures. A simple, rapid and minimum interference with carotenoid and bacteriochlorophyll method to efficiently extract the compounds involving in the formation of 421 nm peak was developed in this study. Assembly of purified MPE with protein components from R. palustris in vitro demonstrated that MPE caused the formation of 421 nm peak. The localization analysis in vivo demonstrated it is MPE associating to protein components and accounting for the peak at ~421 nm. This work clarified the 421 nm peak in vivo mainly originated from MPE accumulation, and will be very helpful to further explore the physiological roles of MPE or its derivatives in photosynthesis.