Seed-induced synthesis of hierarchical architectures of ZSM-5 nanocrystalline aggregates by the solid state crystallization

A seed-induced rapid synthesis of hierarchical ZSM-5 aggregates was achieved by the solid state conversion method in an inorganic system. No secondary mesoporogen was introduced to construct supplementary pore. The physical and chemical properties of the products were characterized by using XRD, SEM, TEM, XRF and N₂ adsorption–desorption techniques. The results revealed that the synthesized samples typically exhibit the uniform spherical zeolite ZSM-5 aggregates composed of loosely packed nanocrystals. It was clearly found that the morphology, mesoporosity and particle size of synthesized samples were directly affected by the type of the seed and synthesis conditions. The well-dispersed hierarchical ZSM-5 aggregates were synthesized at NaOH/SiO₂ = 0.15, 20 ≤ SiO₂/Al₂O₃ ≤ 40 with the acid of zeolite seed solution in guiding the structure. In addition, the crystal growth of zeolite samples synthesized with zeolite seed solution was studied at 433, 453, and 473 K. The results suggested that the activation energies for the induction, transition and crystallization stages were 91.44, 104.37 and 77.68 kJ?mol^?1, respectively. The method provides a cost-effective and industrially applicable route to synthesize hierarchical ZSM-5 aggregates.     

Experimental setup for X-ray spectroscopy of muonic atoms formed from implanted ions in solid hydrogen

An experimental setup comprising of a cryogenic target and an ion implantation system has been constructed to perform muonic X-ray spectroscopy with muonic atoms formed from implanted ions in solid hydrogen films. Gaseous mixtures of hydrogen (H₂) and deuterium (D₂) have been frozen onto a thin 60-mm diameter silver foil, and then irradiated with charged particles of energies up to 33 keV/q. Already, solid films of H₂ and D₂ mixtures with implanted helium ions have been successfully used in muon catalyzed fusion related experiments at RIKEN-RAL Muon Facility. This new method allows studies of the nuclear charge distribution of unstable atoms by means of the muonic X-ray method at facilities where both negative muon and radioactive nuclear beams would be available.     

Spin conversion of hydrogen using supported iron catalysts at cryogenic temperature

Alumina-supported iron oxides have been prepared by incipient wetness impregnation method and employed for orthohydrogen to parahydrogen spin conversion at cryogenic temperature. These materials were characterized using a series of characterization techniques such as SEM, XRD, Raman and in situ FTIR spectroscopy. The spin conversion was investigated at low temperature by a batch mode of operation. The in situ FTIR spectra were collected in a transmission mode to obtain the spin conversion. While the iron oxide was highly dispersed over alumina support at low loading percent, a rodlike crystallite of iron oxide was formed at high loading percent. The 10 and 20 wt% iron oxides on alumina were proved to be the most active catalysts. The spin conversion process was very slow and time-dependent. It was concluded that the spin conversion was a function of various factors including the iron oxide loading percent, calcination temperature, and different supports.     

Influence of different polymers on crystallization tendency and dissolution behavior of cilnidipine in solid dispersions

Context: Cilnidipine (CN) is a novel dihydropyridine calcium antagonist that is practically insoluble in aqueous media and exhibits a low oral bioavailability or limited clinical efficacy.

Objective: This study investigated the effects of three commercial and chemically diverse polymers – PVP, PVP/VA and Soluplus – on crystallization tendency and in vitro dissolution profiles of CN in order to determine an optimum carrier for composing the preferred solid dispersion (SD) of CN.

Methods: All these co-evaporated systems were characterized up to 3 months by thermoanalytical (DSC), crystallographic (POM, PXRD), microscopic (SEM) and spectroscopic (FTIR) techniques.

Results: The results showed that the polymers could be sorted by their effects of inhibiting CN crystallization in the ascending order: Soluplus, PVP/VA, PVP. The sequence was in accordance with that of the strength of drug–polymer hydrogen bonds revealed by FTIR spectra. It could be ascribed to relative hydrogen-bonding acceptor strengths of N-vinylpyrrolidone moiety in the polymer molecules. On the other hand, all the SDs showed enhanced dissolution profiles compared to pure CN alone. On their effects of enhancing CN dissolution, the polymers could be sorted in the descending order: Soluplus, PVP, PVP/VA.

Conclusions: It implied that the dissolution behavior of CN could bear a close relationship to both hydration capacity and hydrogen-bonding interaction tendency of moieties of the polymers. It might suggest an optimal formulation for CN comprising both PVP and Soluplus.     

核聚变用靶丸材料研究进展

激光驱动惯性约束点火是实现核聚变的最有效途径之一,靶丸的设计与制备技术一直是激光惯性约束聚变研究中的核心技术。综述了目前靶丸材料体系的研究现状,重点介绍了理论计算十分有利于点火实验的纯B4C空心微球靶丸。最后,对B4C空心微球靶丸的制备成型工艺进行了展望。     

液氢中固空沉积形式的试验研究

采用向小型液氢可视杜瓦通入定量配比空气的方法,模拟液氢贮存系统受空气污染情况。通过高清摄像设备,得到了固空在液氢中沉积的视频资料。在升温过程中,测量逸出气体中的氧氮浓度,根据不同温度下所测的浓度值绘制氧氮在液氢贮存系统的升温曲线图,从而可得固空中氧氮的分布。     

Sputter deposited LiPON thin films from powder target as electrolyte for thin film battery applications

Lithium phosphorus oxynitride (LiPON) thin films as solid electrolytes were prepared by reactive radio frequency (rf) magnetron sputtering from Li₃PO₄ powder compact target. High deposition rates and ease of manufacturing powder target compared with conventional ceramic Li₃PO₄ targets offer flexibility in handling and reduce the cost associated. Rf power density varied from 1.7 Wcm^− 2 to 3 Wcm^− 2 and N₂ flow from 10 to 30 sccm for a fixed substrate to target distance of 4 cm for best ionic conductivity. The surface chemical analysis done by X-ray photoelectron spectroscopy showed incorporation of nitrogen into the film as both triply, N_t and doubly, N_d coordinated form. With increased presence of N_t, ionic conductivity of LiPON was found to be increasing. The electrochemical impedance spectroscopy of LiPON films confirmed an ionic conductivity of 1.1 × 10^− 6 Scm^− 1 for optimum rf power and N₂ flow conditions.     

Experimental studies of the effect of the ortho/para ratio on the neutronic performance of a liquid hydrogen moderator for a pulsed neutron source

Liquid hydrogen is a realistic cold moderator material for high-power spallation neutron sources. The neutronic performance of a hydrogen moderator depends on the ortho/para ratio of hydrogen, and thus experimental data are needed that will clarify the ortho/para ratio effects on neutronic performance. In this study, we measured the neutronic performance of a liquid hydrogen moderator at several para hydrogen concentrations.Our experiment was performed at the Hokkaido University 45 meV electron linac facility. The neutron energy spectra were measured by the time-of-flight method. Pulse shapes were measured by the Bragg scattering of a mica crystal.The neutron energy spectra change within 20%, depending on the para hydrogen concentrations. With increasing para hydrogen concentration, the pulse peak intensity increases and the pulse width becomes narrower. Furthermore, for a decoupled moderator, the pulse decay becomes faster with increasing para hydrogen concentration. From a viewpoint of the figure of merit (FOM=I/FWHM²) the para hydrogen moderator showed almost the same performance as that of the solid methane moderator, which is considered to be a high performance moderator for pulsed neutron source.     

氢检漏技术在压力容器检漏中的应用

结合中央空调冷水机组和工业冷冻设备用压力容器及氢检漏仪器的特点,介绍氢检漏技术在检漏中的应用,明确氢检漏试验方法,并对其要点进行阐述。     

氢等离子体辅助固相晶化多晶硅薄膜的初步研究

提出一种氢等离子辅助固相晶化(hydrogen plasma assisted solid phase crystallization,H-SPC)多晶硅的新颖技术。这一晶化技术能够明显缩短晶化时间,同时有效钝化多晶硅薄膜的缺陷态。首先对氢等离子辅助SPC技术与传统SPC技术进行比较分析,进而研究了晶化过程中各种工艺条件对多晶硅晶化质量的影响并进行了物理机制的初步分析。     

Ti系合金的室温吸氢平衡压力

观测了具有α相结构的纯Ti、TiZrYAl合金，α β双相结构的TiMo、TiMoSc合金以及近β相结构的TiMoYAlFe和TiMoVYAlFe合金的吸氢PCT曲线和室温平衡压，在室温下各样品的吸氢平衡压约为10^-9～10^-16Pa；α单相合金和α β双相合金的吸氢平衡压略高于纯Ti，但其P—C等温线的斜度增大，吸氢平台长度略有缩短，近β结构合金的室温吸氢平衡压显著高于纯Ti及其它两类合金，增加Al的含量使α相TiZrYAl合金的吸氢平台长度显著缩短，但对平衡压力的影响不大。     

Effect of hydrogen bonding on the viscosity of alcohols at high pressures

Viscosities of several alcohols and vinyl acetate were measured with a rollingball viscometer. The viscosity measurements were performed at temperatures from 298 to 413 K and pressures up to 195 MPa with an accuracy of ±2%. The viscosities of the alcohols show a stronger dependence on temperature compared with that of substances that do not form hydrogen bonds. In addition, the secondary and tertiary alcohols show a viscosity-temperature dependence not in accordance with an Arrhenius law. An effect of pressure on the association of alcohol molecules resulting from hydrogen bonding was not resolved by means of viscosity data. Separation of the effect of association size upon increasing temperature from the viscosity caused by the change of specific volume was carried out using the Utracki free volume model.     

Determination of the parahydrogen fraction in a liquid hydrogen target using energy-dependent slow neutron transmission

The NPDGamma collaboration is performing a measurement of the very small parity-violating asymmetry in the angular distribution of the 2.2 MeV γ-rays from the capture of polarized cold neutrons on protons (A_γ). The estimated size of A_γ is 5×10⁻⁸, and the measured asymmetry is proportional to the neutron polarization upon capture. Since the interaction of polarized neutrons with one of the two hydrogen molecular states (orthohydrogen) can lead to neutron spin-flip scattering, it is essential that the hydrogen in the target is mostly in the molecular state that will not depolarize the neutrons (≥99.8% parahydrogen). For that purpose, in the first stage of the NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE), we operated a 16-l liquid hydrogen target, which was filled in two different occasions. The parahydrogen fraction in the target was accurately determined in situ by relative neutron transmission measurements. The result of these measurements indicate that the fraction of parahydrogen in equilibrium was 0.9998±0.0002 in the first data taking run and 0.9956±0.0002 in the second. We describe the parahydrogen monitor system, relevant aspects of the hydrogen target, and the procedure to determine the fraction of parahydrogen in the target. Also assuming thermal equilibrium of the target, we extract the scattering cross-section for neutrons on parahydrogen.     

Double effects of atomic hydrogen anneal on the microstructure of hydrogenated amorphous silicon films

Hydrogenated amorphous silicon (a-Si:H) films have been deposited with pure silane and then annealed with atomic hydrogen at lower temperature (T_s=170 °C) in a novel, hot wire assisted microwave electron cyclotron resonant chemical vapor deposition system (HW-MWECR-CVD). The experimental results showed that the total hydrogen concentration (C_H) in the film decreased with H₂ flux increase in the atomic hydrogen anneal (AHA) step, but it does not obviously change, keeping at about 3% when H₂ flux increased to a higher value. This is due to double effects of AHA, the crystallization effect at lower substrate temperature and the rehydrogenation effect in low hydrogen concentration films. Furthermore, it was proposed that with increasing R(R=1/{F_hydrogen/(F_silane+F_hydrogen)}, in which F_silane is the silane gas flux in first film synthesis stage and F_hydrogen is the hydrogen gas flux during the annealing step, respectively.), polyhydrides such as SiH_x (x=2 or 3) turn into monohydrides SiH, which results in reducing the network defects, improving the film microstructure and decreasing the optical band gap from 1.644 to 1.557 eV.     

Investigation for the amorphous state of ER-34122, a dual 5-lipoxygenase/cyclooxygenase inhibitor with poor aqueous solubility,in HPMC solid dispersion prepared by the solvent evaporation method

ER-34122, a poorly water-soluble dual 5-lipoxygenase/cyclooxygenase inhibitor, exists as a crystalline form. According to an Oak Ridge thermal ellipsoid plot drawing, carbonyl oxygen O (5) makes an intermolecular hydrogen bond with the hydrogen bonded to N (3) in the crystal structure. The FTIR and the solid-state ¹³C NMR spectra suggest that the network is spread out in the amorphous state and the hydrogen bonding gets weaker than that in the crystalline phase, because the carbonyl signals significantly shift in both spectra. When amorphous ER-34122 was heated, crystallization occurred at around 140°C. Similar crystallization happened in the solid dispersion; however, the degree of crystallization was much lower than that observed in the pure amorphous material. Also, the DSC thermogram of the solid dispersion did not show any exothermic peaks implying crystallization. The heat of fusion (ΔH_f) determined in the pure amorphous material was nearly equal to that for the crystalline form, whereas the ΔH_f value obtained in the solid dispersion was less than a third of them. These data prove that crystallization of the amorphous form is dramatically restrained in the solid dispersion system. The carbonyl wavenumber shifts in the FTIR spectra indicate that the average hydrogen bond in the solid dispersion is lower than that in the pure amorphous material. Therefore, HPMC will suppress formation of the intermolecular network observed in ER-34122 crystal and preserve the amorphous state, which is thermodynamically less stable, in the solid dispersed system.     

Photoelectrochemical properties of sol–gel-derived Ti1−xVxO2 solid solution film photoelectrodes

Ti_1−xV_xO₂ solid solution film photoelectrodes were prepared by the dip-coating sol–gel method. X-ray diffraction and X-ray photoelectron spectroscopy were employed to ensure the formation of the solid solution and their composition. Obvious photoresponses were observed in the visible region for the solid solution film electrodes with x0.05 and the red shift of the photoresponse was enhanced with increasing x. Moreover, the solid solution film electrodes were found to be photoelectrochemically stable. However, the onset potential of photocurrent shifted positively with increasing x. Band model of the solid solution was suggested to explain the effects of the vanadium incorporation on the photoelectrochemical properties.     

Growth of Fe3O4 whiskers from solid solution nanoparticles of Fe–Cu and Fe–Ag systems produced by DC plasma jet method

Fe–Cu and Fe–Ag binary systems are virtually immiscible for a whole range of composition in equilibrium. In the present study, the nanoparticles of Fe–Cu and Fe–Ag systems were produced by direct current plasma jet method. These produced nanoparticles had mean particle sizes of about 70 nm, and were a mixture of bcc and fcc phases. It was revealed by analytical high-resolution TEM observations that the nanoparticles of Fe–Cu and Fe–Ag systems were supersaturated solid solution. It has been found that numerous whiskers with a particle on their tip grow from these nanoparticles by heating above the temperature of 860 K under an Ar–O₂ atmosphere. The whiskers grow as the result of the phase separation in these solid solutions. The whiskers are composed of a Fe₃O₄ rod and a Cu₂O particle on the tip.     

Amphotericin B loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carrier (NLCs): physicochemical and solid-solution state characterizations

Amphotericin B (AmB) is one of the most effective systemic antifungal agents, but its use is circumscribed by the dose-limiting toxicity of the conventional micellar dispersion formulation, Fungizone^®. Significantly lesser toxicity is obtained when AmB incorporated into the aqueous dispersion of lipid nanoparticles. The aim of this study was to develop and characterize AmB loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs). NLC differed from SLN by the presence of liquid lipid, glyceryl tri(caprylate/caprate) in the lipid matrix. Various surfactants i.e. tween 20, cremophor RH40, poloxamer 407 (P407) and Myrj 52 were used to stabilize SLN and NLC. The effect of phospholipid incorporated in those lipid dispersions was also determined. Among surfactants tested, only P407 could stabilize AmB lipid dispersions. There was no chemical reaction occurred between AmB and other components that confirmed by Fourier transform infrared spectroscopy (FT-IR) spectra. The differential scanning calorimetry (DSC), hot-stage microscopy (HSM), powder X-ray diffractometry (PXRD) data showed that AmB was molecularly dispersed or in amorphous form in the lipid matrix. The proton nuclear magnetic resonance (¹H-NMR) results showed that in the presence of phospholipid oil clusters within the lipid matrix are formed. These results indicate that SLN and NLC stabilized by P407 and/or phospholipid as the colloidal carrier for AmB were successfully developed.     

N18、Zry-4和M5锆合金中氢的固溶度

用差示扫描量热法(DSC)研究了含氢20-240μg/g的N18、Zry-4和M5三种锆合金加热时氢化物完全溶解时的固溶度(TSSD)和冷却时氢化物开始析出时的固溶度(TSSP)并使用TSSD或TSSP数据拟合出最优方程.结果表明,这些合金的TSSD或TSSP差别都很小,TSSD与TSSP之间都存在显著的滞后,是氢化物与基体间的体积错配应变所导致.根据冷却时DSC放热峰的宽度,计算出氢化物从过饱和固溶体中析出的平均速率,并拟合出最优方程.氢化物析出的活化能与氢在锆合金中的扩散激活能近似,表明氢化物的析出受到氢扩散的控制.     

Molecular Design of Polymer Heterojunctions for Efficient Solar–Hydrogen Conversion

Semiconducting photocatalytic solar–hydrogen conversion (SHC) from water is a great challenge for renewable fuel production. Organic semiconductors hold great promise for SHC in an economical and environmentally benign manner. However, organic semiconductors available for SHC are scarce and less efficient than most inorganic ones, largely due to their intrinsic Frenkel excitons with high binding energy. In this study the authors report polymer heterojunction (PHJ) photocatalysts consisting of polyfluorene family polymers and graphitic carbon nitride (g‐C₃N₄) for efficient SHC. A molecular design strategy is executed to further promote the exciton dissociation or light harvesting ability of these PHJs via alternative approaches. It is revealed that copolymerizing electron‐donating carbazole unit into the poly(9,9‐dioctylfluorene) backbone promotes exciton dissociation within the poly(N‐decanyl‐2,7‐carbazole‐alt‐9,9‐dioctylfluorene) (PCzF)/g‐C₃N₄ PHJ, achieving an enhanced apparent quantum yield (AQY) of 27% at 440 nm over PCzF/g‐C₃N₄. Alternatively, copolymerizing electron‐accepting benzothiadiazole unit extended the visible light response of the obtained poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole)/g‐C₃N₄ PHJ, leading to an AQY of 13% at 500 nm. The present study highlights that constructing PHJs and adapting a rational molecular design of PHJs are effective strategies to exploit more of the potential of organic semiconductors for efficient solar energy conversion.