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We report a pump-probe femtosecond transient absorption spectroscopic study on the electron transfer reaction of CCl4 in liquid ethanol. By direct observations of the presolvated electron and of the reaction transition state CCl4*-, this study provides direct evidence of the resonant dissociative electron transfer (RDET) of the presolvated electron to CCl4. Moreover, the lifetime of CCl4*- in ethanol is directly obtained from the decay kinetics and its measured value is found to be nearly identical to its gas-phase value. Hence, these results also imply that RDET can be an efficient process in an aqueous environment. [ABSTRACT FROM AUTHOR]

The growth, surface morphology, and electronic binding states of diamondlike films deposited by femtosecond laser ablation on Si wafers at 77 K have been studied in order to elucidate the mechanical properties of this material. Nanoscale buckling has been observed and is found to have a morphology that exhibits a strong dependence on film thickness. Nanobuckling takes the form of quasiperiodic discrete pointlike excursions extending over widths of 50–100 nm. This morphology converts to a regular structure of grooves/ripples with a modulation period of 30–50 nm as the film thickness increases to 300–600 nm. We find that microhardness is not changed in regions where nanobuckling is present. Analysis of Raman and x-ray photoelectron spectra (XPS) demonstrate that nanobuckling can be attributed to the relaxation of internal stress and to the formation of strong C-Si covalent bonds at the C-Si interface. XPS spectra show that the C 1s peak is broadened compared to that found in spectra of films deposited using nanosecond laser ablation. This is found to be consistent with a composition that includes sp, sp2, and sp3-bonded carbon. The unique composition of these films suggests that these materials may find application in electromechanical devices. [ABSTRACT FROM AUTHOR]

A comparative study of carbon bonding states and Raman spectra is reported for amorphous diamondlike carbon films deposited using 120 fs and 30 ns pulsed laser ablation of graphite. The presence of sp1 chains in femtosecond carbon films is confirmed by the appearance of a broad excitation band at 2000–2200 cm-1 in UV-Raman spectra. Analysis of Raman spectra indicates that the concentrations of sp1-, sp2-, and sp3-bonded carbon are ≈6%, ≈43%, and ≈51%, respectively, in carbon films prepared by femtosecond laser ablation. Using surface enhanced Raman spectroscopy, specific vibrational frequencies associated with polycumulene, polyyne, and trans-polyacetylene chains have been identified. The present study provides further insight into the composition and structure of tetrahedral carbon films containing both sp2 clusters and sp1 chains. [ABSTRACT FROM AUTHOR]

Replacement of thymidine in DNA by bromodeoxyuridine (BrdU) has long been known to enhance DNA damage and cell death induced by ionizing/UV radiation, but the mechanism of action of BrdU at the molecular level is poor understood. Using time-resolved femtosecond laser spectroscopy, we obtain the real-time observation of the transition state of the ultrafast electron transfer (ET) reaction of BrdU with the precursor to the hydrated electron, which is a general product in ionizing/UV radiation. The results show that the ET reaction is completed within 0.2 picosecond (ps) after the electronic excitation, leading to the formation of a transition state BrdU*- with a lifetime of ∼1.5 ps that then dissociates into Br- and a high reactive radical dU*. The present results can greatly enhance our understanding not only of the mechanism of BrdU as a radio-/photosensitizer but of the role of prehydrated electrons in electron-initiated processes in biological and environmental systems. [ABSTRACT FROM AUTHOR]

We report that the absolute cross sections for dissociative attachment of ∼0 eV electrons to chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are strongly enhanced by the presence of H[sub 2]O ice. The absolute cross sections for CFCl[sub 3], CHF[sub 2]Cl, and CH[sub 3]CF[sub 2]Cl on water ice are measured to be ∼8.9×10[sup -14], ∼5.1×10[sup -15], and ∼4.9×10[sup -15] cm[sup 2] at ∼0 eV, respectively. The former value is about 1 order of magnitude higher than that in the gas phase, while the latter two are 3–4 orders higher. In contrast, the resonances at electron energies >=2.0 eV are strongly suppressed either for CFCs and HCFCs or for CF[sub 4] adsorbed on H[sub 2]O ice. The cross-section enhancement is interpreted to be due to electron transfer from precursor states of the solvated electron in ice to an unfilled molecular orbital of CFCs or HCFCs followed by its dissociation. This study indicates that electron-induced dissociation is a significant process leading to CFC and HCFC fragmentation on ice surfaces. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present measurements of absolute dissociative electron attachment (DEA) cross sections to CFCl[SUB3], CHF[SUB2]Cl, and CH[SUB3]CF[SUB2]Cl adsorbed on the surface of Kr as a function of electron energy (0-10 eV). The DEA cross sections are measured to be ∼7.2 × 10[SUP-15] cm[SUP2] at ∼0 eV, ∼4.2 × 10[SUP-16] cm[SUP2] at 0.65 eV, and ∼ 7.8 × 10[SUP-16]cm[SUP2] at 0.89 eV for CFCl[SUB3], CHF[SUB2]Cl, and CH[SUB3]CF[SUB2]Cl, respectively. This cross section is similar to the gas-phase value for CFCl[SUB3], while for the latter two molecules, it is orders of magnitude higher than the gaseous values. These results can be explained by considering the changes in the survival probability of the anion resonance and in the electron capture probability due to the decrease of the nuclear wave function overlap in the Franck-Condon region. [ABSTRACT FROM AUTHOR]

Studies the Chlorine[sup -] yield produced by dissociative electron attachment of a submonolayer of CF[sub 2]Cl[sub 2]. Coadsorption of CF[sub 2]Cl[sub 2] with water ice and ammonia ice; Magnitude of Cl[sup -] enhancement; Capture of electrons self-trapped in polar water or ammonia molecules.

Estimation of the temperature distribution, the thermal deformation and the stress, as well as the thermal stable time of a mesoscale micromachined structure attributed to laser irradiation is of great significance because the thermal effects substantially affect a suite of properties. This paper investigates the laser-induced thermal effects of both film bulks and elastic structures with suspensions via finite element (FE) modeling, then proposes a transient model to evaluate them. The temperature variations and the thermal deformations and stresses as functions of the irradiation time are given, in consideration of the incident laser conditions, the ambient temperature, and boundary conditions such as the dimensions of the structure. Some laws and tendencies are found. The study allows for better understanding the mesoscale light-matter interaction and opto-thermal effects; thus, paves the way for the design of high performance devices which contain micromachined structures and equivalent heat sources. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To explore the effect of neurotrophin-3 (NT-3) messenger ribonucleic acid (mRNA) in the hippocampus on infection-induced memory impairment of neonatal rats. MATERIALS AND METHODS: 80 female Sprague-Dawley (SD) rats in the neonatal stage were selected to establish memory impairment model by bacterial meningitis infection. Rats were randomly divided into experimental group (n=40) and control group (n=40). Rats in experimental group were injected with β-amyloid precursor protein 319-335 peptide APP17p into brain tissue to up-regulate the expression of NT-3, and the rats in control group didn't receive treatment. Behavioral changes of rats were observed in Morris water maze and passive avoidance experiment. Apoptosis of nerve cells was detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) method and Fluoro-Jade B method. NT-3 mRNA expression level was measured via reverse transcription polymerase chain reaction (RT-PCR). RESULTS: NT-3 expression level in experimental group was higher than that in control group (p<0.05). Apoptosis rate of nerve cells in experimental group was lower than that in control group, but the learning and memory ability of rats in experimental group was better than that in control group (p<0.05). CONCLUSIONS: Reduced NT-3 expression level may be correlated with the occurrence of meningitis because NT-3 can suppress nerve cell apoptosis and ameliorate learning and memory impairment to a certain extent to exert neuroprotective effects. [ABSTRACT FROM AUTHOR]

The possible influence of various factors on the enhancement of chlorine (Cl)(super -) and Fluorine (F)(super -) yields observed for the electron stimulated desorption (ESD) of CF2Cl2 coadsorbed with polar molecules is examined. Results indicate that the dissociation of CF2Cl2 by capture of electron self-trapped by polar molecules could be responsible for the giant negative-ion enhancements.

Estimation of the temperature distribution, the thermal deformation and the stress, as well as the thermal stable time of a mesoscale micromachined structure attributed to laser irradiation is of great significance because the thermal effects substantially affect a suite of properties. This paper investigates the laser-induced thermal effects of both film bulks and elastic structures with suspensions via finite element (FE) modeling, then proposes a transient model to evaluate them. The temperature variations and the thermal deformations and stresses as functions of the irradiation time are given, in consideration of the incident laser conditions, the ambient temperature, and boundary conditions such as the dimensions of the structure. Some laws and tendencies are found. The study allows for better understanding the mesoscale light-matter interaction and opto-thermal effects; thus, paves the way for the design of high performance devices which contain micromachined structures and equivalent heat sources. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To study the change rules of inflammatory factors in cerebrospinal fluid (CSF) and serum of patients with viral meningitis. PATIENTS AND METHODS: 742 patients with suspected viral meningitis admitted to Department of Neurosurgery in our hospital from August 2012 to May 2016 were selected as research objects and retrospectively analyzed. 536 patients were diagnosed with viral meningitis by CSF with the lumbar puncture and brain computed tomography (CT), while the other 206 patients were diagnosed with non-infectious nervous system disease, as the control group. The levels of inflammatory factors interleukin-6 (IL-6) in peripheral blood and procalcitonin (PCT) in cerebrospinal fluid were detected and compared between two groups of patients. RESULTS: Compared with those in control group, the white blood cell (WBC) count, and levels of serum IL-6 and PCT in cerebrospinal fluid of patients with viral meningitis were all increased (p<0.01). PCT and IL-6 were positively correlated with viral meningitis (r=0.8267, 0.9234). The sensitivity of the two items was 77.81% and 81.32%, respectively, and the specificity was 90.53% and 88.64%, respectively. CONCLUSIONS: The levels of inflammatory factors IL-6 and PCT in serum and CSF of patients with viral meningitis are slightly increased. The detection of the expression levels of IL-6 and PCT in patients with viral meningitis is of great significance for the preliminary diagnosis and rehabilitation of viral meningitis. [ABSTRACT FROM AUTHOR]

The article “Lewy pathological study on α-synuclein in gastrointestinal tissues of prodromal Parkinson’s disease” by Q.-B. Lu, Z.-F. Zhu, H.-P. Zhang, W.-F. Luo, published in Eur Rev Med Pharmacol Sci 2017; 21 (7): 1514-1521 has been withdrawn. [ABSTRACT FROM AUTHOR]

In our recent paper [J. Chem. Phys.128, 041102 (2008)], we reported a femtosecond time-resolved laser spectroscopic study of the electron transfer reaction of CCl4 in liquid ethanol. Our results provide direct evidence of the resonant dissociative electron transfer (RDET) of the presolvated electron to CCl4, and indicate that RDET can be an efficient process in an aqueous environment. In a recent Comment, the author argues that the relevance of diethanolamine (DEA) induced destruction of chlorofluorocarbons (CFCs) in the polar stratosphere as a possible pathway for chemical ozone destruction should not be a motivation for further studies of DEA on CFC molecules, as no correlation is observed between polar chemical ozone loss and cosmic ray activity. Here, we show that this claim is misleading: it is made by using inconclusive and ambiguous data while ignoring pronounced and well-documented data. [ABSTRACT FROM AUTHOR]

Electron-exposure effects on the desorption of F[sup -](Cl[sup -]) and F[sup +](Cl[sup +]) ions from 1 ML CF[sub 2]Cl[sub 2] /Ru(0001), 1 ML CF[sub 2]Cl[sub 2]/1 ML Xe/Ru(0001) and 5 ML CF[sub 2]Cl[sub 2]/Ru(0001) surfaces have been studied. It is observed that for a ≤1 ML CF[sub 2]Cl[sub 2]/Ru surface, the anion yield shows a rapid decrease with increasing electron exposure, while the cation yield exhibits an increase. In contrast, an opposite behavior is observed for a 5 ML CF[sub 2]Cl[sub 2]/Ru surface. For 1 ML CF[sub 2]Cl[sub 2] adsorbed on a 1 ML Xe-spacer layer, the effect tends to switch the behavior from the monolayer to the multilayer. These results indicate that Cl[sup -] ions accumulated on the multilayer or the monolayer surface on a Xe spacer by the polarization potential have an electrostatic effect on the desorption yields of anions and cations. Moreover, from the attenuation of the F[sup -] yield of a 1 ML CF[sub 2]Cl[sub 2]-covered surface with electron exposure, the electron-induced dissociation is estimated to be 9.2(± 2.0) × 10[sup 16]cm[sup 2]. [ABSTRACT FROM AUTHOR]