RESUMEN

Metal-organic frameworks (MOFs) with different topologies formed by the self-assembly of sulfur-containing inorganic ligands, cobalt ions, and large ligands can be used to prepare electrocatalysts for water splitting in order to fully explore the advantages of MOFs in terms of structural tailoring and quantitative assembly. It is possible to avoid using an extradoped sulfur source to reduce waste as well as to disperse Co and sulfur elements evenly and controllably throughout the final material to maximize the overall synergistic effect. In this work, different kinds of bimetallic MOF materials containing sulfur can be synthesized very conveniently by using an economical and practical diffusion method. These materials are directly used as OER electrocatalysts, and the bimetallic MOFs have the best electrocatalytic performance when the ratio of Co to Fe is 6:4. The overpotential at a current density of 10 mA cm-2 was 260 mV, with a Tafel slope of 56 mV dec-1 and good stability. It was assembled with 20% commercial Pt/C material into a two-electrode system for all-water decomposition, and the decomposition voltage at 10 mA cm-2 was 1.81 V. From the electronic configuration microscopic point of view, the introduction of iron ions changed the original synergistic effect for Co-S-Co, which more easily led to the formation of high-valence Co3+ and finally produced highly active electrocatalytic sites. From a macroscopic point of view, the material produced in situ during the electrochemical reaction process not only retains the original 2D layered structure but also utilizes bubbles to produce a loose structure with defective sites. These structural features are advantageous because they provide not only an abundance of active sites and permeable channels but also the necessary interfaces and electron-transport channels for the formation of electrostatic charge-separation layers, making it easier to intercalate and delaminate the hydroxide ions. Furthermore, the changed hydroxyl ions and nitrogen and sulfur atoms on the channel surface may operate as interaction sites, increasing the surface characteristics, facilitating electron transfer, and reducing electron-transfer resistance. To summarize, the rational design of sulfur-containing layered MOF materials directly as water-splitting catalysts is a crucial next step in developing cost-effective, environmentally friendly, and low-energy-consumption electrocatalysts based on the findings of this study.

RESUMEN

In order to give full play to the advantages in structure tailoring and quantitative assembly, metal-organic frameworks (MOFs) with different topological structures formed by the self-assembly of inorganic ligands containing sulfur, cobalt ions and large-size ligands were used to prepare electrocatalyst materials for hydrolysis with controllable composition and performance. According to the synthesis proposition, we can not only avoid using additional doped sulfur sources to reduce waste but also make it very convenient for Co and sulfur elements to be uniformly and controllably distributed in the whole material, and enhance the overall synergistic effects. Based on the above considerations, two-dimensional layered and three-dimensional MOFs, Co-MOF-1, and Co-MOF-2, with the same chemical compositions were utilized as the templates, and a series of Co/S-based materials with variable compositions and properties were obtained only by controlling the pyrolysis temperature. For each MOF series, it can be observed that with the increase in the pyrolysis temperature, the derivatives gradually change from Co4S3 to Co9S8 composites, which could be proven by PXRD studies. The electrocatalytic properties of two series of derivatives were also investigated, and the results indicate that the materials containing Co4S3 can indeed show better water-splitting performance than Co9S8 ones. Furthermore, the macroscopic stacking form of the MOF template also plays an important role in determining the electrocatalytic performance of the derived materials. Through an overall comparison, it is found that the electrocatalytic performance of the Co-MOF-1 series is better than that of the Co-MOF-2 series at various temperatures, which should be only caused by the natural packing modes of the pristine MOF template. For Co-MOF-1 derivatives, the retention of the two-dimensional layered structure is favorable to form an electrostatic charge separation layer and electron transport channel, which is beneficial to the intercalation and delamination of hydroxide ions, thus improving the storage capacity of materials, promoting electron transfer, and producing less electron transfer resistance. Therefore, based on the research results, the reasonable design of layered MOF materials containing the specific sulfur-containing linker as water-splitting catalysts is an applicable route for the preparation of economical, environmentally friendly, and low energy consumption electrocatalysts, which should receive increasing attention in the future.

RESUMEN

Solvothermal reactions of hexakis(4-carboxyphenoxy)cyclotriphospazene (H6L1) with copper ions in DMF/H2O produced one complex, {[Cu6(L1)2(OH)(H2O)3]·guest} n (1), but with copper ions and auxiliary rigid 4,4-bipyridine (bpy) produced another new complex, namely, {[Cu3(L1)(bpy)(H2O)6]·guest} n (2). These complexes had been characterized by IR spectroscopy, elemental analysis, and X-ray structural determination. 1 exhibits a 3D anionic structure with the binodal 4,8-connected network with Schläfli symbol {46}2{49·618·8}, consisting of Cu6 clusters and L1 ligands. In contrast, complex 2 possesses a different 3D network with trinodal 3,4,6-c topology with Schläfli symbol {4·62}2{42·66·85·102}{64·8·10}. In these two complexes, the semirigid hexacarboxylate ligands adopt distinct conformations to connect metal ions/clusters, which must be ascribed to the addition of the auxiliary rigid ligand in reaction systems. In addition, gas absorption properties of 1 and 2 including CO2 and N2 were further investigated.

RESUMEN

Laser processing in the semiconductor industry (especially silicon material) has broad application prospects. The interaction between the laser and silicon is complex, and the present paper mainly studied the silicon morphology in UV laser ablation and the influence law of ambient gas. Studies have shown that the laser plasma ionization effect of silicon in the UV laser ablation has a decisive impact: the removal of the material becomes possible because of generating gasification and ionization, laser plasma shock wave can make phase transition material discharge effectively, and laser plasma spectroscopy ionization effect can make the oxygen elements in the air ionize and deposit effectively.

RESUMEN

The film can be easily damaged by impurity particles, and the damage characteristics of HfO2 film produced by metal particles and the corresponding thermodynamic process were studied. The strong absorption of laser light by metal particles can make film melt, gasified and ionized, and by this way, the film can be peeled and form tround pits point; The metal particle size is closely related to the processes of laser absorption, thermal diffusivity and thermal expansion closely related effects, etc. Under the same irritation energy, the temperature rise is determined by particle size, which can make different size of film damage pits. There is a certain size of metal particle which cause the highest temperature rise and make the film damage easily. Based on the analysis of irradiation ionization effects of laser plasma emission spectrum of the metal particles, the radiation spectrum is mainly focused on the ultraviolet part and photon energy is higher than the incident laser, which has stronger ionization effects, exacerbating the film removal.

RESUMEN

The study on the mechanism of laser ablated cells is of importance to laser surgery and killing harmful cells. Three radiation modes were researched on the ablation characteristics of onion epidermal cells under: laser direct irradiation, focused irradiation and the laser plasma radiation. Based on the thermodynamic properties of the laser irradiation, the cell temperature rise and phase change have been analyzed. The experiments show that the cells damage under direct irradiation is not obvious at all, but the focused irradiation can cause cells to split and moisture removal. The removal shape is circular with larger area and rough fracture edges. The theoretical analysis found out that the laser plasma effects play a key role in the laser ablation. The thermal effects, radiation ionization and shock waves can increase the deposition of laser pulses energy and impact peeling of the cells, which will greatly increase the scope and efficiency of cell killing and is suitable for the cell destruction.

Asunto(s)

RESUMEN

The research and development of the KTP crystal with high threshold is of very importance for its application in high-energy laser systems. Ablation characteristics in KTP crystal as well as their influence on the Raman spectroscopy were studied by UV laser with high repetition frequency. The research results show that the laser plasma effects are the main reasons for the damage in the KTP crystal. The inverse bremsstrahlung absorption effect can increase the deposition of the laser pulse energy greatly; the ionization effect can make the crystal dislocated completely; shock wave effect can push away the mixture of melted, vaporized and ionized materials and cause cracks in the pit. Through investigation and comparison of the Raman spectroscopy before and after the laser ablation, it was found that the distribution characteristics of Raman peaks are almost the same, suggesting that the basic structures of KTP crystal do not change. But almost all the Raman characteristic peaks' R1R values have changed and the widths are broadened, which means that the crystalline degree has been decreased. The Raman peaks of TiO6 and PO4 oxygen polyhedron shift to the lower wave number, which indicates that bonding force becomes weaker and the KTP crystal can be damaged easily.

RESUMEN

Optical components with higher surface quality and higher damage threshold requirement are necessary in high-energy/power laser system, which strongly depends on the performance of optical thin films. The damage morphologies on the surface of the HfO2/SiO2 anti-reflection film, caused by focused laser pulses, were investigated in the present paper. The studies revealed that the shock wave formed with the expansion of laser plasma, and its velocity and pressure decease rapidly with the radius. The spectrum of laser plasma, recorded by EEP2000 spectrometer, shows that the wavelength of laser plasma radiation is shorter than incident laser, which will increase the probability of multi-photon absorption; the photon energy in deep ultraviolet region, higher than the band gap of HfO2, can be absorbed directly. The ionization effect of laser plasma can easily induce film damage. The combination of shock wave and ionization effect determines the damage morphology of films. In the case of laser pulse focused on the film surface, the radiation and shock wave effects are the highest, not only the film is removed, but also the quartz substrate is broken-down. When the focus point is away from the film surface to a certain distance, the radiation of laser plasma and shock wave decrease rapidly, as a result, no damage can be found except that the thin-film can be peeled away from the substrate.

RESUMEN

OBJECTIVE: To explore the interaction of Anxa2 with P-Glycoprotein (P-gp) in the migration and invasion of the multidrug-resistant (MDR) human breast cancer cell line MCF-7/ADR. METHODS: A pair of short hairpin RNA (shRNA) targeting P-gp was transfected into MCF-7/ADR cells, and monoclonal cell strains were screened. The expression of P-gp was detected by Western blot. Transwell chambers were used to observe the cell migration capacity and invasion ability. The interaction between P-gp and Anxa2 was examined by immunoprecipitation and immunofluorescence confocal microscopy analyses. RESULTS: P-gp expression was significantly knocked down, and there were notable decreasing trends in the migration and invasion capability of MDR breast cancer cells (P<0.05). There was a close interaction between Anxa2 and P-gp. CONCLUSIONS: MCF-7/ADR is an MDR human breast cancer cell line with high migration and invasion abilities. The knockdown of P-gp notably impaired the migration and invasion abilities of the tumor cells. The interaction of Anxa2 with P-pg may play an important role in the enhanced invasiveness of MDR human breast cancer cells.

RESUMEN

The present paper reports a double pass forward superfluorescent fiber source (SFS), which uses a length of large mode area double cladding ytterbium doped fiber as gain medium. The maximum output power of this SFS is 341 mW. With the output power between 201 and 341 mW, the 3dB bandwidth of this SFS was more than 80 nm. This is the widest 3 dB bandwidth obtained from ytterbium doped SFS. The output power of the SFS linearly increased with the increment of the pump source injected current. It's output power is not very high, but under normal circumstances, it could meet the needs of the SFS. From the energy level structure of ytterbium ions and the absorption cross-section/emission cross section of ytterbium ions in quartz substrate, the physical mechanisms responsible for superfluorescence were analyzed. This double-cladding ytterbium-doped superfluorescent fiber laser benefits from the superfluorescence radiation near 1 025 and 1 075 nm, so the superfluorescence with 3 dB bandwidth reaching up to 80 nm could be obtained.

RESUMEN

Silicon is the basic material for electro-photonic detectors, so the studies of the laser induced damage of silicon are of great significance in laser detecting and military applications. The damage characters of silicon under high intensity nanosecond laser pulses were investigated in the present paper. The results show that laser plasma has thermal effect, shock effect and spectral radiation effect, etc. These comprehensive effects combined together determinate the damage characters. By thermal effects and shock effects of laser plasma, the material is being melt, vaporized, ionized and pushed out at the laser irradiated area. In this way, the pit can be formed and the cooled ejected effluents are radially distributed. The silicon was melt at the bottom of the pit and the temperature was modulated by the intensity of the incident laser, which interfered with scattering laser simultaneously. The periodic heat distribution generates the period stripes. N, O and Si characteristic spectrum in the laser plasma prove that the colored film is the mixture of SiOx:SiNy which were sprayed out from laser plasma under repetitive laser pulses.

RESUMEN

In an attempt to elucidate the damage in high transmission thin films on LiNbO3 crystal in optical parametric oscillator, the authors employed XRD spectrometry to investigate the spectrum of laser-induced damage in thin film as well as the morphology of the damage. The authors observed that the damage of thin film was characterized by the depressions/craters in the surface of the films, which were surrounded by a deposition layer with the deceasing thickness from the center of the craters. The XRD measurements indicate that the film was crystallized. The authors analyzed the causes of morphologies and the mechanism of crystallization with the aid of the model for impurity-induced damage in thin solid films. The crystallization was due to the solidification of liquid and gaseous mixtures that result from the strong absorbing to the incident laser. The crater was generated because the mixtures were ejected under the extensive pressure of the laser plasma shock wave. During the process that the mixtures deposit around the craters, the density of the mixtures will decrease and crystallization takes place. As a result, the color of the deposition layer becomes lighter from inside to outside, and the crystallization of the thin film materials was observed by XRD spectrometry.

RESUMEN

The free electron density and temperature of laser-induced plasma and the damage on the silicon surface were investigated. The results show that the volume and the free electron density of laser induced plasma, as well as the plasma temperature will determine the profile and the size of silicon superficial damage. It was also found that the volume of laser plasma will increase continuously and the temperature will increase slightly with the increase in the energy of laser pulse, while the density of free electrons will remain invariable. The free electron density and the temperature reduce gradually from centre to edge, so the damage appearance has the following features: The interior area of damage was melted so well that the periodic stripes were formed. The periodic stripes were quite irregular for the area not melted very well. The boundary of damage is apparent and sometimes color changes induced by plasma spattering were observed.

RESUMEN

OBJECTIVE: To evaluate the immuno-effects of hepatitis B (HB) vaccination in adults. METHODS: Five groups were sampled by means of cluster sampling, and serum HBsAg, anti-HBs and anti-HBc were tested in every group at people aged from 18 to 50. Recombinant HB vaccine was injected to the ones that HBsAg, anti-HBs and anti-HBc were all negative. Concentration of anti-HBs in serum was tested after one year and three years of vaccination. Immuno-effects of recombinant HB vaccination in adults at different ages and between sexes, were then calculated. RESULTS: Good immuno-effects of recombinant HB vaccination in adults were noticed. After one year and three years of vaccination with 5 micro g recombinant HB vaccine, the anti-HBs positive rates were 82.76%, 70.77% while the serum concentrations of anti-HBs were 55.91 mIU/ml and 35.41 mIU/ml respectively. When 10 micro g was used, the concentrations were 83.74%, 72.22%, 56.89 mIU/ml and 30.29 mIU/ml respectively. The effects did not show significant differences between different doses on 10 micro g and of 5 micro g. Concentration of anti-HBs reduced when time went by. The factors such as age and sex influenced the effects of immunity on recombinant HB vaccination. CONCLUSION: Good immunity could be obtained when recombinant hepatitis B was vaccinated in vulnerable population aged 18 to 50.

Asunto(s)