Advanced TFA-MOD process of high critical current YBCO films for coated conductors

Although the metalorganic deposition (MOD) process using metal trifuluoroacetete (TFA) is considered to be a strong candidate due to its low cost and high J_c performance as a fabrication process for coated conductors of YBa₂Cu₃O_7 − x (YBCO), the long calcination time of 10 h for 300 nm YBCO thickness was a problem that needed to be solved in the case of the MOD process using the TFA salts for all elements (all TFA solution). In this study, in order to shorten the calcination time, a new combination of starting materials was developed. Through the investigation of the generation rate of hydro fluoride (HF) gas during calcination, it was found that the high generation rate at a high heating rate is the reason for the bubbling which prevents an increase of the heating rate. Therefore, the amount of fluorine (F) in the starting material was reduced by using the Cu-salt without F while maintaining the basic crystallization reaction in this process. A new heating process using these materials has been developed. Consequently, the calcination time was shortened to 40% using the All TFA solution and an overall transport I_c value of 292 A for 1 cm width was obtained (77 K in self-field).     

Simulation of Stable Crack Growth for Welded Joints Including Strength Mismatching

1.IotroductionStrengthmismatchingeffectsonfracturetough-nessofferritesteelsremainakeyissueforthesafetyassessmentofstructures.Structuralandpressureves-selsteelsgenerallyexhibitincreaseinfracturetough-nessoverthefirstfewdistanceofstablecrackgrowth.Laboratorytestingoffracturespecimenstomeasureresistancecurves(R-curves)consistentlyrevealsamarkedeffectofstrengthmismatchingonR-curves.Fortheweldedjoint,whoseweldmetalstrengthishigherthanthatofthebasemetal(overmatching),yieldahigherRcurvecomparingwit…     

Optical Pyrometry of Fireballs of Metalized Explosives

Fast‐response optical diagnostics (a time‐integrated spectrometer and two separate fast‐response three‐color pyrometers) are used to record the transient visible radiation emitted by a fireball produced when a condensed explosive is detonated. Measurement of the radiant intensity, in several narrow wavelength bands, is used to estimate the temperature of the condensed products within the fireball. For kg‐scale conventional oxygen‐deficient homogeneous TNT and nitromethane explosive charges, the radiant intensity reaches a maximum typically after tens of milliseconds, but the measured fireball temperature remains largely constant for more than 100 ms, at a value of about 2,000 K, consistent with predictions using equilibrium thermodynamics codes. When combustible metal particles (aluminum, magnesium or zirconium) are added to the explosive, reaction of the particles enhances the radiant energy and the fireball temperature is increased. In this case the fireball temperatures are lower than equilibrium predictions, but are consistent with measurements of particle temperature in single particle ignition experiments.     

DCTN1 Binds to TDP-43 and Regulates TDP-43 Aggregation

A common pathological hallmark of several neurodegenerative diseases, including amyotrophic lateral sclerosis, is cytoplasmic mislocalization and aggregation of nuclear RNA-binding protein TDP-43. Perry disease, which displays inherited atypical parkinsonism, is a type of TDP-43 proteinopathy. The causative gene DCTN1 encodes the largest subunit of the dynactin complex. Dynactin associates with the microtubule-based motor cytoplasmic dynein and is required for dynein-mediated long-distance retrograde transport. Perry disease-linked missense mutations (e.g., p.G71A) reside within the CAP-Gly domain and impair the microtubule-binding abilities of DCTN1. However, molecular mechanisms by which such DCTN1 mutations cause TDP-43 proteinopathy remain unclear. We found that DCTN1 bound to TDP-43. Biochemical analysis using a panel of truncated mutants revealed that the DCTN1 CAP-Gly-basic supradomain, dynactin domain, and C-terminal region interacted with TDP-43, preferentially through its C-terminal region. Remarkably, the p.G71A mutation affected the TDP-43-interacting ability of DCTN1. Overexpression of DCTN1^G71A, the dynactin-domain fragment, or C-terminal fragment, but not the CAP-Gly-basic fragment, induced cytoplasmic mislocalization and aggregation of TDP-43, suggesting functional modularity among TDP-43-interacting domains of DCTN1. We thus identified DCTN1 as a new player in TDP-43 cytoplasmic-nuclear transport, and showed that dysregulation of DCTN1-TDP-43 interactions triggers mislocalization and aggregation of TDP-43, thus providing insights into the pathological mechanisms of Perry disease and other TDP-43 proteinopathies.     

Experimental study of hydrodynamic propulsion of a medical device with a spiral ribbed impeller

In order to minimize injury during a medical treatment using a low invasive sliding device, loss of cells and tissues due to wear against the device must be prevented by maintaining good lubrication condition. For this purpose, a new medical device with a spiral ribbed impeller has been presented. This paper shows the potentials and problems of the proposed mechanism through experiments. The experimental result confirms that a device can be driven by thrust force keeping noncontacting condition. In some cases, however, the measured thrust force was lower than the theoretical prediction. Cavitation was observed through the transparent impeller in a visualized experiment. It is suggested that a rupture of fluid film associated with cavitation may limits the thrust force and injure tissues. Viscous liquid should be supplied to suppress cavitation if the quantity of the existing mucus is not sufficient.     

Hydrodesulfurization of dibenzothiophenes over molybdenum catalyst supported on TiO2–Al2O3

Composite types of TiO₂–Al₂O₃ supports, which are γ-aluminas coated by titania, have been prepared by chemical vapor deposition (CVD), using TiCl₄ as a precursor. Then supported molybdenum catalysts have been prepared by an impregnation method. As supports, we employed γ-alumina, anatase types of titania, and composite types of TiO₂–Al₂O₃ with different loadings of TiO₂. We studied the conversion of Mo from oxidic to sulfidic state through sulfurization by X-ray photoelectron spectroscopy (XPS). The obtained spectra unambiguously revealed the higher reducibility from oxidic to sulfidic molybdenum species on the TiO₂ and TiO₂–Al₂O₃ supports compared to that on the Al₂O₃ support. Higher TiO₂ loadings of the TiO₂–Al₂O₃ composite support led to higher reducibility for molybdenum species. Furthermore, the catalytic behavior of supported molybdenum catalysts has been investigated for hydrodesulfurization (HDS) of dibenzothiophene (DBT) and methyl-substituted DBT derivatives. The conversion over the TiO₂–Al₂O₃ supported Mo catalysts, in particular for the 4,6-dimethyl-DBT, is much higher than that obtained over Al₂O₃ supported Mo catalyst. The ratio of the corresponding cyclohexylbenzene (CHB)/biphenyl (BP) derivatives is increased over the Mo/TiO₂–Al₂O₃. This indicates that the prehydrogenation of an aromatic ring plays an important role in the HDS of DBT derivatives over TiO₂–Al₂O₃ supported catalysts.     

Influence of the structure of the nanotube on the mechanical properties of binder-free multi-walled carbon nanotube solids

We prepared and characterized multi-walled carbon nanotube (MWCNT) solids by de-fluorination of fluorinated MWCNTs using spark plasma sintering. In order to investigate the influence of the structure of MWCNT on the mechanical strength of the resulting solids, MWCNTs used in this experiment were as-defected MWCNTs modified by nitric acid and as-purified ones as non-defected nanotubes by comparison. The bend strength and modulus of the resulting solids were lower than those of de-fluorinated MWCNT solids derived from as-purified MWCNTs. The mechanical properties of the resulting MWCNT solids were found to be strongly dependent on the structure of the MWCNT.     

CdSe/SiO2荧光微球的制备及其荧光性能

利用Stber法制备了CdSe/SiO2荧光微球。用透射电子显微镜,共聚焦显微镜和X射线衍射测试荧光微球的形貌和晶体结构;用荧光光谱表征荧光微球的荧光性能;用动态-静态激光散射仪表征荧光微球的尺寸分布。结果表明:CdSe量子点被包裹在SiO2微球内,并形成了具有良好荧光性能的CdSe/SiO2荧光微球,其荧光性能与合成工艺条件有着显著的相关性。     

Mechanical Properties of CoAl Materials with the Combined Additions of ZrO2(3Y) and Al2O3

Intermetallic CoAl powder has been prepared via self-propagating high-temperature synthesis (SHS). Dense CoAl materials (99.6% of theoretical) with the combined additions of ZrO₂(3Y) and Al₂O₃ have been fabricated via spark plasma sintering (SPS) for 10 min at 1300°C and 30 MPa. The microstructures are such that tetragonal ZrO₂ (0.3 μm) and Al₂O₃ (0.5 μm) particles are located at the grain boundaries of the CoAl (8.5 μm) matrix. Improved mechanical properties are obtained; especially the fracture toughness and the bending strength of the materials with ZrO₂(3Y)/Al₂O₃= 16/4 mol% are 3.87 MPa·m^1/2 and 1080 MPa, respectively, and high strength (>600 MPa) can be retained up to 1000°C.     

Effect of Scale and Confinement on Gap Tests for Liquid Explosives

The factors influencing initiation of detonation in gap tests for liquid explosives are investigated experimentally. A calibrated donor charge (nitromethane) and PMMA attenuator disk arrangement are used to transmit shocks of known strength (2–10 GPa) into a test explosive of nitromethane sensitized with 5% diethylenetriamine. The test explosive is contained in capsules of different wall materials (PVC, Teflon, aluminum), and the dimensions of the charges vary from 25 mm to 100 mm in diameter. For the small‐scale charges, the presence of the confining wall of the test capsule is seen to have a pronounced effect on the detonation initiation. Certain wall materials (PVC, Teflon) exhibit a multi‐valued critical gap thickness, meaning that a weaker shock may result in initiation while a stronger shock does not. The effect of the wall materials could not be correlated with their acoustic or shock impedance, and the only way to eliminate these effects was to make the diameter of the test charge larger than the donor charge. When the size of the donor charge was increased, the critical pressure required for initiation decreased. These results could be correlated to “ideal” shock initiation experiments that use flyer plates as shock sources assuming that lateral rarefactions quench detonation initiation if they reach the central axis of the charge before the onset of detonation is complete.