Preparation of Mesoporous Si Nanoparticles by Magnesiothermic Reduction for the Enhanced Reactivity.

In this study, mesoporous silicon nanoparticles (M-Si) were successfully prepared by a magnesiothermic reduction of mesoporous silica nanoparticles, which were synthesized by a templated sol-gel method and used as the precursors. M-Si exhibited a uniform size distribution with an average diameter of about 160 nm. The measured BET surface area was 93.0 m2 g-1, and the average pore size calculated by the BJH method was 16 nm. The large internal surface area provides rich reaction sites, resulting in unique interfacial properties and reduced mass diffusion limitations. The mechanism of the magnesiothermic reduction process was discussed. The reactivity of prepared M-Si was compared with that of commercially available non-porous Si nanopowder (with the average diameter of about 30 nm) by performing simultaneous thermogravimetry and differential scanning calorimetry in the air. The results showed that the reaction onset temperature indicated by weight gain was advanced from 772 °C to 468 °C, indicating the promising potential of M-Si as fuel for metastable intermolecular composites.

Fragmentation Dynamics of a Carbon Dioxide Dication Produced by Ion Impact.

The response of carbon dioxide to radiolysis is crucial for understanding the atmospheric chemistry of planets. Here, we present a combined experimental and theoretical investigation of the three-body fragmentation dynamics of CO22+ to C+ + O+ + O initiated by 1 keV/u Ar2+ impact. Taking advantage of the kinematic complete measurement employing a reaction microscope, three dissociation mechanisms are distinguished, and their branching ratios are determined. The concerted fragmentation with two C-O bonds breaking simultaneously is dominant, while the sequential pathway with CO+ as the intermediate also makes a significant contribution. Also, a novel isomerization pathway with transitory formation of O2+ is identified. The identified mechanisms can contribute to O+ and O escaping from the Martian atmosphere, since the kinetic energies of most of the fragments are observed to be higher than the escape energy of oxygen.

Exploration of Tuina Effect and Mechanism in Chronic Atrophic Gastritis Rats.

BACKGROUND: Chronic atrophic gastritis is a very common condition in the general clinical practice of gastroenterology. Tuina treatment is widely used clinically. The aim of our study was to investigate the mechanisms of tuina in rats with chronic atrophic gastritis. METHODS: Fifty-six specific pathogen-free grade rats were employed for our study. They were divided into 5 groups and treated differ- ently. Body weight was recorded every week, and their small intestine propulsive ratio was measured after intragastric administration of carbon powder. Histopathological observation of gastric tissues was performed using hematoxylin and eosin staining. The levels of motilin and gastrin in serum were detected by enzyme-linked immunosorbent assay, and the expression levels of Bcl-2 and cytochrome C were measured by the western blot assay. RESULTS: There was no significant difference in body weight and small intestine propulsive ratio between the chronic atrophic gastritis model group and the tuina group (P > .05). However, we can see some significant changes in histomorphology after treatment with tuina. For example, the atrophy of gastric mucosal epithelium and glands had improved, and the inflammatory cells infiltrating the lamina propria were decreased significantly. Moreover, the level of gastrointestinal hormone GAS was increased (P < .001), and there was no statistically significant difference in motilin, Bcl-2, and cytochrome-c after treatment with tuina (P > .05). CONCLUSION: Our research demonstrated the effectiveness of tuina treatment on chronic atrophic gastritis with a possible underlying mechanism that affected the secretion of gastric acid, which could provide some useful information for clinical application.

Management of Acquired Uterine Arteriovenous Malformations Associated with Retained Products of Conception.

PURPOSE: To evaluate the efficacy and safety of different treatments for acquired uterine arteriovenous malformations associated with retained products of conception (UAVM-RPOC) and to investigate the role of uterine artery embolization (UAE) in acquired UAVM-RPOC. MATERIALS AND METHODS: This was a retrospective study of consecutive patients who were diagnosed with uterine arteriovenous malformation by ultrasound after recently terminated pregnancy. Forty-eight patients were included in this study and were divided into 2 groups (major and minor bleeding groups) according to vaginal bleeding. The treatments were analyzed between groups. Technical and clinical success rates of UAE were analyzed. RESULTS: Of the 48 patients, 11 patients were in the massive bleeding group and 37 were in the minor bleeding group. Five patients were referred for UAE in each group and UAE was a priority for patients with unstable hemodynamics (chi-square value = 5.524, P =.022). Conservative management, dilation and curettage (D&C), operative hysteroscopy, and UAE were performed in 16 (33%), 18 (38%), 7 (15%), and 13 (27%) patients, respectively. Two patients with ectopic pregnancies suffered uncontrollable bleeding during D&C and required emergent UAE. Three patients underwent UAE before surgery to prevent hemorrhage. The technical and clinical success rates of UAE were 100%. No complications or recurrences occurred. CONCLUSIONS: UAE is a safe and effective treatment for UAVM-RPOC and a priority for patients with unstable hemodynamics. Conservative management, D&C, and hysteroscopy are safe and effective for patients with UAVM-RPOC with stable hemodynamics. However, UAVM-RPOC following ectopic pregnancy may have high risks of massive hemorrhage during procedures.

Design and characterization of a velocity-map imaging apparatus for low-energy photo-ion spectroscopy using magneto-optically trapped atoms.

We present a velocity-map imaging (VMI) apparatus coupled with a magneto-optical trap (MOT) of 87Rb atoms designed for low-energy photo-ion spectroscopy. The VMI-electrode geometry uses a three-electrode configuration, and the focusing electric field is optimized based on systematic simulations of relatively low-energy ions. To calibrate the apparatus, we use resonant two-color two-photon ionization of rubidium atoms as Doppler-selected ions. This VMI system provides an accuracy of 0.15 m/s and a resolution of 7.5 m/s for photoions with speeds below 100 m/s. Finally, details of the design, construction, and testing of the VMI-MOT system are presented.

Chinese massage, Tui Na, combined with herbs improves clinical symptoms and regulates sex hormones in patients with mammary gland hyperplasia.

To study the effects of Tui Na therapy on patients with mammary gland hyperplasia.A total of 68 female patients with mammary gland hyperplasia were included in this retrospective study from May 2016 to May 2017 and assigned into control group (N = 34) treated with Rupixiao only (a proprietary Chinese medicine) or Tui Na group (N = 34) treated with Tui Na (Chinese massage) combined with Rupixiao. The pain intensity (visual analogous scale, VAS) and serum levels of luteinizing hormone (LH), estradiol (E2), prolactin (PRL), and progesterone (P) were examined before and after the treatment.The efficacies were 94.1% (32/34) in the Tui Na group and 76.5% (26/34) in the control group (P = .04). After treatment, VAS in Tui Na groups was significantly lower than that in control group (2.1 ±â€Š1.1 vs 3.1 ±â€Š1.1, P < .05). After follow-up for five months, the recurrence rates were 12.5% (4/32) in the Tui Na group and 23.1% (6/26) in the control group (P = .01). The levels of all 4 hormones in the Tui Na group increased significantly after treatment. In control group, only LH and E2 levels were significantly increased after treatment.In patients with mammary gland hyperplasia, Tui Na combined with Rupixiao could improve clinical symptoms, regulate sex hormone levels, and decrease the recurrence rate than Rupixiao alone. Our finding suggests that Tui Na can be potentially used for the treatment of mammary gland hyperplasia.

Two-body dissociation of C3H4 isomers investigated by 50 keV/u Ne8+ impact.

The fragmentation of two isomers of C3H4, propyne (CH3CCH) and allene (CH2CCH2), is investigated by 50 keV/u Ne8+ impact. Obvious isomer effects are observed by comparing the time-of-flight spectra generated from the two isomers. Six two-body fragmentation channels of C3H4 2+ dications are identified for each isomer. CH2 + + C2H2 + is found to be the most favored CC bond breaking channel for both isomers, indicating that CH3CCH2+ intends to rearrange to the structure containing the CH2 group before fragmentation. For CH bond breaking channels, it is found that the CH3CCH which contains a CH3 group is more efficient for H2 + and H3 + ejection. In addition, two-body dissociation channels of C3H4 3+ trications are identified. While the H+ + C3H3 2+ channel is observed in the fragmentation of both isomers, the H2 + + C3H2 2+ channel only occurs in the fragmentation of CH3CCH3+. For CH2CCH2 3+, the peak and shoulder structures in the kinetic energy release spectrum of the H+ + C3H3 2+ channel are attributed to different geometries of the C3H3 2+ product.

Multiple ionization state of Arq+ ions during collisions near the Bohr velocity.

In order to clarify the mechanism and the influence of the initial charge state and target atomic parameters for the formation of L-shell multiple ionization state of Arq+ ions produced by the collisions near the Bohr velocity, the k-shell x-ray emission of Ar is measured for 1.2 MeV Arq+(q=4, 6, 8, 9, 11, 12) ions impacting on V target and 3 MeV Ar11+ ions interacting with selected targets (Z2 = 23, 26, 27, 28, 29, 30). It is found that the measured Ar Kα and Kß x-ray energies shift to the high energy side, and the relative intensity ratios of Kß/Kα are enlarged than the atomic data, owing to the presence of out-shell multiple vacancies. The multiple ionization is almost independence of the projectile charge state, but is diminished with increasing target atomic number.

[Analysis of risk factors for preoperative mechanical ventilation in patients with acute traumatic cervical spinal cord injury].

OBJECTIVE: To analyze the risk factors associated with mechanical ventilation before surgery in patients with acute traumatic cervical spinal cord injury(TCSCI). METHODS: According to whether preoperative mechanical ventilation, 59 patients with TCSCI admitted to our hospital from November 2016 to May 2018 were divided into mechanical ventilation(MV)group (37 cases) and non-mechanical ventilation(non-MV) group (22 cases). Falling from height was the most common causes of injury(30 cases, 50.8%), then was traffic accident(22 cases, 37.3%). The most common paraplegic plane was in C1-C4(36 cases, 61%). American Spinal Cord Injury Association(ASIA) injury degree and ASIA exercise score(AMS) were used to assess the extent of affected neurological plane and spinal cord injury. Trauma severity score(ISS) was used to evaluate the severity of the injury. Multivariate Logistic regression was used to analyze the risk factors for mechanical ventilation in TCSCI. ROC curves were used to assess the value of AMS and ISS in predicting mechanical ventilation. RESULTS: Univariate analysis showed that the percentage of male, complete injury and related injuries in the MV group were significantly higher than those in the non-MV group(P<0.05). The AMS score of the MV group was significantly lower than that of the non-MV group (16.4±10.7 vs 39.1±9.5, P<0.001), and the ISS score was significantly higher than that of the non-MV group(31.6±8.0 vs 26.5±6.7, P=0.015). Multivariate Logistic regression analysis showed that AMS[OR=3.340, 95% CI(1.321, 6.242), P<0.001] and ISS [OR=1.120, 95% CI(0.306, 3.786), P<0.001] were significant risk factors on predicting the need for mechanical ventilation.The ROC analysis showed that the area under the ROC curve(AUC) of AMS was significantly higher than that of ISS(0.899 vs 0.685, P<0.05). CONCLUSIONS: AMS and ISS at admission can be used as predictors of early mechanically assisted ventilation.

Dissociation of [HCCH]2+ to H2+ and C2+: a benchmark reaction involving H migration, H-H combination, and C-H bond cleavage.

We report the formation of H2+ and C2+ from dissociation of acetylene induced by α-particle irradiation. The unusual dissociation channel [C2H2]2+ → H2+ + C2+ is unambiguously identified by measuring the time-of-flight of both fragmented ions in coincidence. Our quantum chemical calculation confirms the existence of this dissociation pathway. It shows that [HCCH]2+ is firstly populated to the 3Π excited electronic state, followed by acetylene-vinylidene isomerization, and finally the vinylidene-like intermediate dissociates to H2+ and C2+. This dissociation channel is the simplest prototypical reaction involving H migration, H-H combination, and C-H bond cleavage. The current study plays an important role for understanding the H2+/H3+ formation reactions from organic di-cations in an interstellar medium.

Damaging Intermolecular Energy and Proton Transfer Processes in Alpha-Particle-Irradiated Hydrogen-Bonded Systems.

Although the biological hazard of alpha-particle radiation is well-recognized, the molecular mechanisms of biodamage are still far from being understood. Irreparable lesions in biomolecules may not only have mechanical origin but also appear due to various electronic and nuclear relaxation processes of ionized states produced by an alpha-particle impact. Two such processes were identified in the present study by considering an acetylene dimer, a biologically relevant system possessing an intermolecular hydrogen bond. The first process is the already well-established intermolecular Coulombic decay of inner-valence-ionized states. The other is a novel relaxation mechanism of dicationic states involving intermolecular proton transfer. Both processes are very fast and trigger Coulomb explosion of the dimer due to creation of charge-separated states. These processes are general and predicted to occur also in alpha-particle-irradiated nucleobase pairs in DNA molecules.

An (e, 2e + ion) investigation of dissociative ionization of methane.

We present in this paper an (e, 2e + ion) investigation of the dissociative ionization of methane by 54 eV electron impact employing the advanced reaction microscope. By measuring two electrons and the ion in the final state in triple coincidence, the species of the ions are identified and the energies deposited into the target are determined. The species and the kinetic energies of the fragmented ion show strong dependence on the intermediate states of the parent ion. Possible decay pathways for the production of different species of ions are analyzed.

[Microelements in potato and lily samples studied by laser-induced breakdown spectroscopy technology].

A LIBS setup was built in the Institute of Modern Physics. In our experiments, LIBS spectra produced by infrared radiation of Nd:YAG nanosecond laser with 100 and 150 mJ pulse energy, respectively, were measured by fiber optic spectrometer in the ranges of 230-430 nm and 430-1 080 nm with a delay time of 1.7 and gate width of 2 ms for potato and lily samples prepared by vacuum freeze-dried technique. The lines from different metal elements such as K, Ca, Na, Mg, Fe, Al, Mn and Ti, and nonmetal elements such as C, N, O and H, and some molecular spectra from C2, CaO, and CN were identified according to their wavelengths. The relative content of the six microelements, Ca, Na, K, Fe, Al, and Mg in the samples were analyzed according to their representative line intensities. By comparison we found that there are higher relative content of Ca and Na in lily samples and higher relative content of Mg in potato samples. The experimental results showed that LIBS technique is a fast and effective means for measuring and comparing the contents of microelements in plant samples.

[Anterior surgery for fourth lumbar burst fractures].

OBJECTIVE: To evaluate the clinical outcomes of anterior decompression, bone graft and internal fixation in treating fourth lumbar burst fractures with iliac fenestration. METHODS: From February 2001 to May 2006, 8 cases of fourth lumbar burst fractures were treated by anterior decompression, correction, reduction, iliac autograft, Z-plate internal fixation with-iliac fenestration. Of them, there were 7 males and 1 female, aging 24-46 years with an average of 29.3 years, including 3 cases of Denis type A and 5 cases of Denis type B. The decompression, intervertebral height were compared between preoperation and postoperation by CT scanning. According to Frankel assessment for neurological status, 2 cases were at grade C, 5 at grade D and 1 at grade E before operation. Four cases had different degrees of disturbance of sphincter. Time from injury to operation was 8 hours to 11 days. The preoperative height of the anterior border of the L4 vertebral body was (13.8 +/- 2.3) mm, the Cobb angel of fractured vertebral body was (13.2 +/- 2.5) degrees, the vertebral canal sagittal diameter of L4 was (10.6 +/- 3.5) mm. The bone graft volume was (7.5 +/- 1.3) cm3 during operation. RESULTS: Operations were performed successfully. The mean operative time was (142 +/- 25) minutes and the mean amount of blood loss was (436 +/- 39) mL. The incisions obtained healing by first intention after operation. Two cases suffered donor site pain and received no treatment. The follow-up time of 8 cases was from 21 months to 52 months (mean 24.5 months). At one week after operation, the height of the anterior border of the L4 vertebral body was (32.5 +/- 2.6) mm, the Cobb angel of fractured vertebral body was (6.8 +/- 3.7) degrees, and the vertebral canal sagittal diameter of L4 was (19.8 +/- 5.1) mm, showing significant difference when compared with those of preoperation (P < 0.01). At the final follow-up, the results showed that the pressure was reduced sufficiently, all autograft fused well, the neurological status improved at Frankel grade from C to D in 1 patient, from D to E in 3 patients, but the others had no improvement. In 4 patients who had disturbance of sphincter, 3 restored to normal and 1 was better off. CONCLUSION: Clinical outcomes of anterior surgery for fourth lumbar burst fractures with iliac fenestration are satisfactory. It can facilitate operation, reduce the pressure sufficiently, maintenance intervertebral height and recover the neurological function.

High-energy picosecond near-vacuum ultraviolet pulses generated by sum-frequency mixing of an amplified Ti:sapphire laser.

We demonstrate high-energy picosecond near-vacuum ultraviolet laser pulse generation. Frequency quadrupling is achieved by noncollinear sum-frequency mixing of the fundamental and the third harmonic of a two-stage Ti:sapphire amplifier in beta-BaB(2)O(4) crystal. UV pulses with energies of approximately 10 mJ tunable from 195 to 210 nm at a 10 Hz repetition rate are obtained.

[Cost-effectiveness analysis of the current measures for malaria prevention in Yuanjiang valley, Yunnan province].

OBJECTIVE: To evaluate the cost-effectiveness analysis of the measures currently used for malaria prevention in the region of Yuanjiang River Valley. METHODS: The efficacy and cost-effectiveness analysis of chemoprophylaxis, single DDT residual spraying and a combination of both were evaluated through three field intervention trials. RESULTS: (1) From July to November, the rate ratio of malaria incidence among building workers of expressway as the group of chemoprophylaxis using combined piperaquine/sulfadoxine once per month was 0.35 (95% CI: 0.20-0.59); the cost per individual protected (CIP) and the cost per case averted (CCA) were RMB 6.69 yuan and RMB 459 yuan respectively. (2) In the hyper-endemic villages near the river, the rate ratio in the group using chloroquine plus primaquine once every 10 days for 5 months was 0.28 (95% CI: 0.08-0.99); the CIP and CCA were RMB 5.30 yuan and RMB 300 yuan respectively. (3) The standardized morbidity ratio (SMR) was 100%, 98% and 50% respectively for the chemoprophylaxis group with pyrimethamine/sulfadoxine once per month from May to September, the group with single DDT residual spraying in April and the group of combined chemoprophylaxis and DDT spraying. The CIP was RMB 1.49, 2.48 and 3.97 yuan for the three groups respectively. As compared with the previous year, no cases were averted from the chemoprophlaxis group; the CCA was RMB 14,535 yuan and 908 yuan respectively for the DDT spraying group and the group with combined measures. CONCLUSION: There was no significant difference on the chemoprophylaxis cost between the group using piperaquine/sulfadoxine combination once per month and that of chloroquine plus primaquine once per ten days. However, the study proved an efficacy for malaria prevention in the former but not in the latter. In comparison with the groups of single measures, the group with combined measures showed the best efficacy and effectiveness, but highly expensive.