Dissociation dynamics of carbon dioxide cation (CO2 +) in the C2Σg + state via [1+1] two-photon excitation.

The dissociation dynamics of CO2 + in the C2Σg + state has been studied in the 8.14-8.68 eV region by [1+1] two-photon excitation via vibronically selected intermediate A2Πu and B2Σu + states using a cryogenic ion trap velocity map imaging spectrometer. The cryogenic ion trap produces an internally cold mass selected ion sample of CO2 +. Total translational energy release (TER) and two-dimensional recoiling velocity distributions of fragmented CO+ ions are measured by time-sliced velocity map imaging. High resolution TER spectra allow us to identify and assign three dissociation channels of CO2 + (C2Σg +) in the studied energy region: (1) production of CO+(X2Σ+) + O(3P) by predissociation via spin-orbit coupling with the repulsive 14Πu state; (2) production of CO+(X2Σ+) + O(1D) by predissociation via bending and/or anti-symmetric stretching mediated conical intersection crossing with A2Πu or B2Σu +, where the C2Σg +/A2Πu crossing is considered to be more likely; (3) direct dissociation to CO+(A2Π) + O(3P) on the C2Σg + state surface, which exhibits a competitive intensity above its dissociation limit (8.20 eV). For the first dissociation channel, the fragmented CO+(X2Σ+) ions are found to have widely spread populations of both rotational and vibrational levels, indicating that bending of the parent CO2 + over a broad range is involved upon dissociation, while for the latter two channels, the produced CO+(X2Σ+) and CO+(A2Π) ions have relatively narrow rotational populations. The anisotropy parameters ß are also measured for all three channels and are found to be nearly independent of the vibronically selected intermediate states, likely due to complicated intramolecular interactions in the studied energy region.

N-loss photodissociation dynamics of N2O+(B2Π) near the NO+(Σ+1) + N(2P) dissociation limit.

Photodissociation dynamics of the N2O+ cation in its B2Π state has been experimentally studied in an energy region around the NO+(1Σ+) + N(2P) dissociation limit using a cryogenic cylindrical ion trap velocity map imaging spectrometer. The results show that the NO+(1Σ+) + N(2D) product channel dominates the dissociation dynamics and requires the NNO angle to change by 30°-50° prior to dissociation. The NO+(1Σ+) + N(2P) product channel, which directly correlates with the B2Π state but less competitive, opens immediately when the photon energy reaches the dissociation limits, indicating a flat dissociation pathway without bending on the B2Π state surface.

A2Πu and 14Σu- States of Br2+ Studied by [1+1] Two-Photon Dissociation Spectroscopy in a Cold Ion Beam.

The A2Πu-X2Πg and 14Σu--X2Πg electronic transition spectra of Br2+ have been studied in the 500-720 nm wavelength range in a cold ion beam using a cryogenic cylindrical ion trap velocity map imaging spectrometer. The cryogenic ion trap produces a rotationally and vibrationally cold mass selected ion beam of Br2+, which simplifies the experimental spectra from vibrational hot bands and bands of mixed isotopic species. Vibrationally resolved photofragment excitation spectra are recorded for individual isotopologues of Br2+ (79Br2+, 79Br81Br+, 81Br2+) by [1+1] two-photon dissociation spectroscopy. Velocity map imaging of the photofragmented Br+ ions provides complementary information in the determination of spin-orbit states involved in corresponding electronic transitions. An experimental identification of the 14Σu- state has becomes possible based on the present experimental results and previously reported theoretical calculations. Vibrational analyses of the photofragment excitation spectra have yielded spectroscopic parameters, including state origins, harmonic frequencies, and anharmonic constants, for both A2Πu and 14Σu- states. The observed A2Πu state spin-orbit splitting and the "spin-forbidden" 14Σu--X2Πg transition band intensities indicate considerable spin-orbit couplings between the 14Σu- and A2Πu states. In addition, two groups of weak vibrational bands are also observed in the experimental spectra of 79Br81Br+, which may be due to symmetry-forbidden transitions from the X2Πg ground state to low-lying gerade states.

A cryogenic cylindrical ion trap velocity map imaging spectrometer.

A cryogenic cylindrical ion trap velocity map imaging spectrometer has been developed to study photodissociation spectroscopy and dynamics of gaseous molecular ions and ionic complexes. A cylindrical ion trap made of oxygen-free copper is cryogenically cooled down to ∼7 K by using a closed cycle helium refrigerator and is coupled to a velocity map imaging (VMI) spectrometer. The cold trap is used to cool down the internal temperature of mass selected ions and to reduce the velocity spread of ions after extraction from the trap. For CO2 + ions, a rotational temperature of ∼12 K is estimated from the recorded [1 + 1] two-photon dissociation spectrum, and populations in spin-orbit excited X2Πg,1/2 and vibrationally excited states of CO2 + are found to be non-detectable, indicating an efficient internal cooling of the trapped ions. Based on the time-of-flight peak profile and the image of N3 +, the velocity spread of the ions extracted from the trap, both radially and axially, is interpreted as approximately ±25 m/s. An experimental image of fragmented Ar+ from 307 nm photodissociation of Ar2 + shows that, benefitting from the well-confined velocity spread of the cold Ar2 + ions, a VMI resolution of Δv/v ∼ 2.2% has been obtained. The current instrument resolution is mainly limited by the residual radial speed spread of the parent ions after extraction from the trap.

Photodissociation dynamics of OCS at ∼210 nm: The role of c(23A″) state.

Photodissociation dynamics of carbonyl sulfide (OCS) in the deep ultraviolet region is investigated using a time-sliced ion velocity map imaging technique. The measured total kinetic energy release spectra from the photodissociation of OCS at ∼210 nm shows three dissociation channels to the fragment S(1D2), corresponding to low, medium, and high kinetic energy release (ET), respectively. The high ET channel is found to be a new dissociation channel opening with photolysis wavelength at ∼210 nm. Based on the aq(k)(p) polarization parameters as well as the anisotropy parameters ß determined from the images of S(1D2), the dissociation of OCS to S(1D2) + CO at 210 nm is concluded to involve a direct vertical excitation of the triplet c(23A″) state from the ground state, followed by processes as: the low ET component arises from a non-adiabatic transition from the repulsive A(21A') state to the electronic ground state X(11A'); the medium ET component arises from a simultaneous excitation to two repulsive excited states; and the high ET component arises from the intersystem crossing from the triplet c(23A″) state to the repulsive A(21A') state. The present study shows that, due to the strong spin-orbit coupling between the triplet c(23A″) state and the repulsive A(21A') state, a direct excitation to c(23A″) significantly contributes to the photodissociation dynamics of OCS in the deep-UV region.

MicroRNA-592 targets IGF-1R to suppress cellular proliferation, migration and invasion in hepatocellular carcinoma.

MicroRNAs (miRs) can function as tumor suppressors or oncogenes in different types of human malignancy, and may provide an effective therapy for cancer. The expression and functions of miR-592 have previously been studied in relation to cancer. However, the expression and potential functions of miR-592 in hepatocellular carcinoma (HCC) are still unknown. Using quantitative polymerase chain reaction, MTT assays, cellular migration and invasion assays, bioinformatics software, western blot analysis and dual-luciferase report assays, the present study explored the expression and roles of miR-592 in HCC. It was identified that miR-592 was significantly downregulated in HCC tissues and cell lines. The statistical analysis revealed that low expression of miR-592 was evidently associated with tumor node metastasis stage and lymph node metastasis. Additionally, the present study provided the first evidence that miR-592 was likely to directly target the insulin-like growth factor 1 receptor in vitro. The present results indicated that miR-592 could be investigated as an efficacious therapeutic target for HCC in the future.

[Value of tumor deposits in staging and prognostic evaluation in gastric cancer patients].

OBJECTIVE: To analyze relationships between the tumor deposits (TD) and clinicopathologic features of gastric cancer and investigate the value of TD in staging and prognosis in gastric cancer patients. METHODS: Retrospective cohort study was conducted to evaluate the clinicopathologic data of 388 gastric cancer patients who underwent surgical procedures in Chinese PLA General Hospital between November 2011 and December 2012. Relationships between TD and clinicopathologic features were analyzed by χ2 or Fisher exact tests. Survival curves were also generated by Kaplan-Meier method. The univariate and multivariate analysis were performed with Log-rank and COX proportional hazard model to examine the association between prognosis and TD. RESULTS: TD were observed in 67 (17.3%) of 388 gastric cancer patients, including 48 male patients (48/289, 16.6%) and 19 female patients (19/99, 19.2%). There were 40 patients (40/198, 20.2%) whose age was above 64 years old. TNM staging of positive TD patients was as follows: for pathology, there were 5 patients (5/64, 7.8%) in stage II(b, 6 patients (6/58, 10.3%) in stage III(a, 14 patients (14/75, 18.7%) in stage III(b, 30 patients (30/135, 22.2%) in stage III(c, 12 patients (12/39, 30.8%) in stage IIII( and no one in stage I(b or II(a; for T-staging, there were 2 patients (2/18, 11.1%) in stage T2, 2 patients (2/27, 7.4%) in stage T3, 36 patients (36/259, 13.9%) in stage T4a and 27 patients (27/84, 32.1%) in stage T4b; for N-stage, there were 5 patients (5/72, 6.9%) in stage N0, 6 patients (6/72, 8.3%) in stage N1, 19 patients (19/82, 23.2%) in stage N2, 27 patients (27/100, 27.0%) in stage N3a and 10 patients(10/62, 16.1%) in stage N3b; for M-stage, there were 12 patients (12/40, 30.0%) in distal metastases; for vascular invasion, there were 29 patients (29/129, 22.5%). Among positive TD patients, the number of TD >3 was found in 38 of 67 cases(56.7%). TD was associated with pTNM-stage (χ2=16.898, P=0.010), T-stage (χ2=17.382, P=0.001), N-stage (χ2=18.080, P=0.001), M-stage (χ2=5.060, P=0.036) and vascular invasion(χ2=3.675, P=0.039). The median survival time of positive TD patients was significantly shorter as compared to negative TD patients (22 months vs. 32 months, χ2=23.391, P=0.012). Among positive TD patients, the median survival time of patients with TD number >3 was significantly shorter as compared to those with TD number <3 (17 months vs. 25 months, χ2=5.157, P=0.023). Multivariate survival analysis showed that TD number >3 was the independent risk factor of prognosis (RR=2.350, 95%CI:1.345 to 4.106, P=0.003). CONCLUSIONS: TD state is closely associated with the staging of gastric cancer and TD number >3 indicates a poor prognosis.

Temporally Distinct Six2-Positive Second Heart Field Progenitors Regulate Mammalian Heart Development and Disease.

The embryonic process of forming a complex structure such as the heart remains poorly understood. Here, we show that Six2 marks a dynamic subset of second heart field progenitors. Six2-positive (Six2+) progenitors are rapidly recruited and assigned, and their descendants are allocated successively to regions of the heart from the right ventricle (RV) to the pulmonary trunk. Global ablation of Six2+ progenitors resulted in RV hypoplasia and pulmonary atresia. An early stage-specific ablation of a small subset of Six2+ progenitors did not cause any apparent structural defect at birth but rather resulted in adult-onset cardiac hypertrophy and dysfunction. Furthermore, Six2 expression depends in part on Shh signaling, and Shh deletion resulted in severe deficiency of Six2+ progenitors. Collectively, these findings unveil the chronological features of cardiogenesis, in which the mammalian heart is built sequentially by temporally distinct populations of cardiac progenitors, and provide insights into late-onset congenital heart disease.

[Protective effect of adenosine preconditioning against spinal cord ischemia-reperfusion injury in rats].

OBJECTIVE: To study the effect of adenosine preconditioning on cell apoptosis and expressions of glucose-regulated protein (GRP-78) and cysteinyl aspartate-specific protease 12 (caspase-12) in rats with spinal cord ischemia-reperfusion injury. METHODS: Twenty-seven rats were randomized into 3 equal groups and subjected to sham operation (group A), spinal cord ischemia-reperfusion injury (group B), or ischemia-reperfusion injury with adenosine treatment. Spinal cord ischemia-reperfusion injury was induced by cross-clamping of the abdominal aorta inferior to the left renal artery. The spinal cord function was assessed using the Modified Tarlov Scale at 6, 12, and 24 h after reperfusion. At 24 h after reperfusion, histological analysis was carried out with HE staining; cell apoptosis and viability were determined with TUNEL staining, and the expressions of GRP-78 and caspase-12 proteins were determined with Western blotting. RESULTS: HE staining of the spinal cord showed extensive spinal cord injury such as cell edema in group B as compared with group C. Compared with group A, group B showed a significantly increased number of apoptotic cells; the number of apoptotic cells in group B was greater than that in group C. Compared with group B, group C showed significantly increased GRP-78 expression (P<0.01) and decreased caspase-12 expression (P<0.01). CONCLUSION: Adenosine can up-regulate GRP-78 expression and down-regulate caspase-12 expression, and protects the spinal cord against ischemia-reperfusion injury by inhibiting cell apoptosis.

[Protective effect of retrograde venous perfusion of cryogenic liquid via accessory hemiazygos vein and treated with resveratrol on spinal cord injury in swine].

OBJECTIVES: To observe the protective effect of retrograde venous perfusion of cryogenic liquid via accessory hemiazygos vein and treated with resveratrol on spinal cord injury and evaluate the expression changes of microtubule-associated protein 2 (MAP-2) after spinal cord ischemia reperfusion injury (SCII) in swine. METHODS: Eighteen swine were divided into 3 groups: group I/R (n = 6, operation group), group CL (n = 6, retrograde venous perfusion of cryogenic liquid), group CL+Res (n = 6, retrograde venous perfusion of cryogenic liquid and treated with resveratrol after ischemia). In the group I/R, the aorta was clamped for 60 minutes and then removed. In the group CL and CL+Res, 9 g/L cold (4 °C) saline solution (perfusion rate, 16.65 ml/min) was infused into the accessory hemiazygos vein during ischemia.In the group CL+Res, the swine were treated with resveratrol (10 mg/kg) after spinal cord ischemia. Arterial pressure, blood gas analysis and the spinal canal and nasopharyngeal temperature changes were monitored during the surgery. Nervous function were assessed at 6 hours, 1, 2 days, 1, 2, 4 weeks and MAP-2 expression were detected at 4 weeks after reperfusion by using Western blot analysis in spinal cord tissue. RESULTS: After operation 18 swine were all survival. Behavioral scores of all groups decreased until 1 week after reperfusion and increased as time went by. The scores of group CL and CL+Res were higher than group I/R (F = 8.612, 17.276 and 11.985, P = 0.035,0.011 and 0.023) at 6 hours, 1, 2 days, group CL+Res were higher than group CL(P = 0.021) at 1 days after surgery. After descending aortic cross clamping, the spinal canal and nasopharyngeal temperature were obviously decreased in all groups and dropped to the lowest at 60 minutes after ischemia and 20 minutes after reperfusion in group I/R and the other groups respectively(F = 23.187-55.029, P < 0.01).In group CL(0.54 ± 0.26) and CL+Res (0.66 ± 0.31), the MAP-2 expression were higher than group I/R(0.37 ± 0.18) (F = 9.381, P = 0.037) , and the level in group CL+Res was higher than in group CL (P = 0.021) . CONCLUSION: Retrograde venous perfusion of cryogenic liquid via accessory hemiazygos vein and treated with resveratrol can relieve the ischemia-induced spinal cord injury in swine.

Acoustic intensity-based method for sound radiations in a uniform flow.

An acoustic intensity-based method (AIBM) is extended and verified for predicting sound radiation in a subsonic uniform flow. The method assumes that the acoustic propagation is governed by the modified Helmholtz equation on and outside of a control surface, which encloses all the noise sources and nonlinear effects. With acoustic pressure derivative and its co-located acoustic pressure as input from an open control surface, the unique solution of the modified Helmholtz equation is obtained by solving the least squares problem. The AIBM is coupled with near-field Computational Fluid Dynamics (CFD)/Computational Aeroacoustics (CAA) methods to predict sound radiation of model aeroacoustic problems. The effectiveness of this hybrid approach has been demonstrated by examples of both tonal and broadband noise. Since the AIBM method is stable and accurate based on the input acoustic data from an open surface in a radiated field, it is therefore advantageous for the far-field prediction of aerodynamics noise propagation when an acoustic input from a closed control surface, like the Ffowcs Williams-Hawkings surface, is not available [Philos. Trans. R. Soc. London, Ser. A 264, 321-342 (1969)].

An acoustic intensity-based method for reconstruction of radiated fields.

An acoustic intensity-based method is proposed for the reconstruction of acoustic radiation pressure. Unlike the traditional inverse acoustic methods, the proposed method includes the acoustic pressure gradient as an input in addition to its simultaneous, co-located acoustic pressure in a radiated field. As a result, the reconstruction of acoustic radiation pressure from the input acoustic data over a portion of a surface enclosing all the acoustic sources, i.e., an open surface, becomes unique due to the unique continuation theory of elliptic equations. Hence the method is more stable and the reconstructed acoustic pressure is less dependable on the locations of the input acoustic data. Furthermore, the proposed method can be applied for both inverse and forward problems up to the minimum sphere enclosing the sources of interest. The effectiveness of the method is demonstrated by the results of several acoustic radiation examples with single or multi-frequency source in a two-dimensional configuration. The results from the method also show a measurable improvement in accuracy and consistency of reconstructed acoustic radiation pressure, in particular when the effect of the signal-to-noise ratio is included.